tag:theconversation.com,2011:/us/topics/rhythm-27240/articlesRhythm – The Conversation2023-10-01T15:12:16Ztag:theconversation.com,2011:article/2068322023-10-01T15:12:16Z2023-10-01T15:12:16ZWe got the beat: How we perceive rhythm involves neurological processes that control movement<figure><img src="https://images.theconversation.com/files/535420/original/file-20230703-268647-i4u2qr.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C7153%2C4781&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Experiencing the beat of a rhythm may be influenced
by the body’s expectation of movement.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/we-got-the-beat-how-we-perceive-rhythm-involves-neurological-processes-that-control-movement" width="100%" height="400"></iframe>
<p>When you hear a song playing somewhere, you might find yourself tapping your fingers or moving your head to the rhythm. If you’re walking, your footsteps may fall in line with the beat. Whether or not you’re a musician, somehow you know intuitively when to speed up or slow down to stay in time. </p>
<p>A wide range of living and non-living systems show synchronization, the tendency to coordinate rhythmic activity across interconnected groups. Pendulum clocks hanging on the same wall <a href="https://physicsworld.com/a/the-secret-of-the-synchronized-pendulums/">eventually sync up</a>, and large groups of fireflies may start to <a href="https://www.firefly.org/synchronous-fireflies.html">flash as one</a>.</p>
<p>But <a href="https://www.newscientist.com/article/mg24232240-600-most-animals-cant-keep-a-beat-despite-what-darwin-believed/">nothing else in the natural world</a> spontaneously synchronizes with rhythms across such a wide range of tempos and with such precision as humans listening to music. Joining the flow of a rhythmic piece of music is something we think of as almost automatic. But as pleasant and natural as it may be, it’s not at all clear how we do it. </p>
<p>As a musician, I spend many happy hours synchronizing to rhythms. And as a scientist, I am fascinated by the processes in the mind and brain that allow us to interact so expertly and spontaneously with rhythm. </p>
<h2>Rhythm and the brain</h2>
<p>Our sense of rhythm would seem to begin within the confines of the mind. As we listen to rhythmic music, we intuitively know when the next note is likely to occur. We are surprised when our rhythmic expectations are thwarted, as when a prominent downbeat is <a href="https://doi.org/10.1111/psyp.13909">played slightly early or is intentionally left silent</a>. </p>
<p>But it appears that even our ability to mentally follow and anticipate musical rhythms is tied up with the brain processes we use to move our bodies. </p>
<p>Using <a href="https://www.yalemedicine.org/conditions/functional-mri-imaging-the-brain">functional MRI</a>, music neuroscientists have <a href="https://doi.org/10.1016/j.neubiorev.2022.104588">established</a> that actively listening to rhythm activates the <a href="https://doi.org/10.1038/nrn2478">supplementary motor area</a> of the cerebral cortex and the <a href="https://doi.org/10.1001/archneur.60.10.1365">basal ganglia</a> in the deep brain, both of which are important for generating voluntary movements.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/535417/original/file-20230703-227943-4xq7eg.jpg?ixlib=rb-1.1.0&rect=0%2C85%2C5694%2C2949&q=45&auto=format&w=1000&fit=clip"><img alt="people in an exercise class mid-step" src="https://images.theconversation.com/files/535417/original/file-20230703-227943-4xq7eg.jpg?ixlib=rb-1.1.0&rect=0%2C85%2C5694%2C2949&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/535417/original/file-20230703-227943-4xq7eg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=320&fit=crop&dpr=1 600w, https://images.theconversation.com/files/535417/original/file-20230703-227943-4xq7eg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=320&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/535417/original/file-20230703-227943-4xq7eg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=320&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/535417/original/file-20230703-227943-4xq7eg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=403&fit=crop&dpr=1 754w, https://images.theconversation.com/files/535417/original/file-20230703-227943-4xq7eg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=403&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/535417/original/file-20230703-227943-4xq7eg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=403&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">As we move our bodies in space, we are continuously monitoring the state and progress of our actions using the sensory feedback they produce.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>How is mentally following a rhythm similar to moving our bodies? In my research, I am exploring <a href="https://www.youtube.com/watch?v=6SBI24s6KnI">one possible link</a>: As we move our bodies in space, we are continuously monitoring the state and progress of our actions using the sensory feedback they produce. </p>
<p>This process of monitoring resembles a <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/kalman-filter">Kalman filter</a>, an algorithm used to track the movement of objects based on limited and noisy measurements. </p>
<p>I recently showed that the process of following the cycle of a periodic beat underlying a complex rhythm can also be approximated surprisingly well by <a href="https://doi.org/10.1371/journal.pcbi.1009025">a version of the Kalman filter</a>. Anticipating and processing events in a rhythm may draw on the same brain mechanisms as anticipating and processing the sensory consequences of our own movements. </p>
<p>From an evolutionary perspective, I suspect that our sense of rhythm developed (at least in part) as an outgrowth of <a href="https://doi.org/10.1177/2059204319892617">monitoring and anticipating our own footsteps</a> as we walk or run.</p>
<h2>Causes of motor disorders</h2>
<p>Drawing links between motor control and rhythm perception may help us make sense of the underlying causes of neurological disorders that both affect rhythm perception and benefit from rhythm-focused therapies, including <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5322262/">Parkinson’s</a>, <a href="https://pubmed.ncbi.nlm.nih.gov/31450508/">Huntington’s</a>, and stuttering.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/535418/original/file-20230703-257123-rl7hkr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a girl looks at a metronome on a table" src="https://images.theconversation.com/files/535418/original/file-20230703-257123-rl7hkr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/535418/original/file-20230703-257123-rl7hkr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=535&fit=crop&dpr=1 600w, https://images.theconversation.com/files/535418/original/file-20230703-257123-rl7hkr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=535&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/535418/original/file-20230703-257123-rl7hkr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=535&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/535418/original/file-20230703-257123-rl7hkr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=672&fit=crop&dpr=1 754w, https://images.theconversation.com/files/535418/original/file-20230703-257123-rl7hkr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=672&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/535418/original/file-20230703-257123-rl7hkr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=672&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Using a metronome can help alleviate stuttering.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>Developmental stuttering (a stutter during speech that arises in early childhood) is associated with <a href="https://doi.org/10.1016/j.bandl.2022.105219">impairment in rhythm perception</a> and <a href="https://doi.org/10.3389/fpsyg.2015.00847">weaker ability to tap in time with a metronome</a>. </p>
<p>Conversely, stuttering can be partially alleviated <a href="https://doi.org/10.1016/S0005-7894(71)80001-1">by speaking along with a metronome</a>. Further, stutterers often experience substantially improved speech when their speech is played back to them with a <a href="https://doi.org/10.1016/j.jfludis.2006.04.001">slight delay or a pitch shift</a>. </p>
<p>Understanding the link between processing motor feedback — like the sound of one’s own speech — and perceiving an underlying beat could help us better understand stuttering by unifying the primary speech impairments with the secondary effects relating to rhythm and feedback as parts of a larger picture.</p>
<h2>Rhythm and boundaries</h2>
<p>The study of rhythm is one gateway to bigger questions about our relationship with the world around us. I believe that how we sense rhythm blurs the boundaries between our internal and external worlds.</p>
<p>We simply don’t have the cognitive resources to take all the information coming in our ears and rapidly separate it into multiple rhythmic streams. As a result, the rhythms we hear become entangled with the rhythms we make with our bodies. As we play music in a group, we literally lose ourselves in the rhythm: we no longer predict the timing of our own sounds separately from the mix, but instead predict the timing of all sounds based on <a href="https://doi.org/10.7554/eLife.74816">the group’s rhythm as a whole</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/P2ngriiCuME?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Drummers cannot experience more than one internal beat at a time.</span></figcaption>
</figure>
<h2>Prediction and action</h2>
<p>So when we play music with others or slip into step with a friend on a walk, how does the rhythm we hear come to commandeer the timing of our actions? I suspect that the last ingredient is the tight relationship between prediction and action. According to one exciting theory of the neural control of action, we move our bodies <a href="https://doi.org/10.1007/s00429-012-0475-5">not by sending “commands” to them, but instead by predicting what we will experience</a> when we move them. </p>
<p>For example, when I fully expect to experience the sound and feeling of a handclap, my body aligns with my expectations and I clap my hands. This is one way to understand some people’s tendencies to finish others’ sentences: once they have a clear prediction of what they are going to hear, it is difficult to avoid producing those sounds themselves.</p>
<p>A shared rhythmic experience is a fluid interplay between sound, external expectations, self-expectation and action. As I come to understand the rhythm I’m hearing and predict its sounds, I start to predict the timing of my own actions with the same clock. And when I do that, <a href="https://www.youtube.com/watch?v=l8FbKeqRY08">my actions can’t help but align themselves with my predictions</a>.</p>
<p>In this way, listening to and playing rhythmic music is a way to feel and act as a part of something larger than ourselves. We no longer experience ourselves as fully separate sources of sound and action — instead, we move and experience our movement as if music and movement all come from the same source, a source that includes us not as individuals but as parts of a larger system. </p>
<p>In a culture that often treats us as fundamentally separate and compartmentalized individuals, music helps us experience our minds, our bodies, other people, and our environments as an integrated whole.</p><img src="https://counter.theconversation.com/content/206832/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jonathan Joseph Cannon does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Humans can spontaneously fall into rhythms with precision, and across a wide range of tempos. This may be because the same neurological processes that anticipate rhythm are involved with movement.Jonathan Joseph Cannon, Assistant Professor of Psychology/Neuroscience/Behavior, McMaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2068252023-07-27T12:25:54Z2023-07-27T12:25:54ZDeaf rappers who lay down rhymes in sign languages are changing what it means for music to be heard<figure><img src="https://images.theconversation.com/files/539659/original/file-20230726-15479-kw9iix.png?ixlib=rb-1.1.0&rect=10%2C17%2C1851%2C1237&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Rapper Beautiful The Artist performs in the music video for the dip hop song 'DEAFinitely Lit.'</span> <span class="attribution"><a class="source" href="https://www.youtube.com/watch?v=PbyBd87VpXI">Beautiful The Artist/YouTube</a></span></figcaption></figure><p>In April 2023, <a href="https://www.facebook.com/DeafDjSupalee/">DJ Supalee</a> hosted <a href="https://www.facebook.com/photo?fbid=650074507126012&set=pcb.650074560459340">Supafest Reunion 2023</a> to celebrate entertainers and promoters within the U.S. Deaf community.</p>
<p>The event included performances by R&B artist and rapper <a href="https://www.facebook.com/shoroc81/">Sho’Roc</a>, female rapper <a href="https://www.facebook.com/beautifultheartist/">Beautiful The Artist</a>, the group <a href="https://www.rit.edu/ntid/sunshine">Sunshine 2.0</a>, DJs <a href="https://roctheparty.com/about-us/">Key-Yo</a> and <a href="https://www.djhearnoevil.net/">Hear No Evil</a>, as well as ASL performer and former rapper Polar Bear, who now goes by <a href="https://www.tiktok.com/@reddd.menace">Red Menace</a>. </p>
<p>Many of these artists, activists and entrepreneurs have contributed to an ever-growing hip-hop scene within the Deaf community, which includes a subgenre of rap known as <a href="https://www.pbs.org/video/rapper-warren-wawa-snipe-hip-hop-deaf-community-dzlu7a/">dip hop</a>.</p>
<p>As hip-hop reaches its <a href="https://theconversation.com/us/topics/hip-hop-50-135779">50th anniversary</a>, five decades of its <a href="https://theconversation.com/after-rappers-delight-hip-hop-went-global-its-impact-has-been-massive-so-too-efforts-to-keep-it-real-206373">cultural impact reverberates</a> in mainstream and underground settings. What originated in the Bronx can now be found all over the world, taking on new forms as it has evolved in a diversity of spaces and places, from <a href="https://online.berklee.edu/takenote/trap-music-where-it-came-from-and-where-its-going/">trap music</a> and <a href="https://www.okayplayer.com/originals/horrorcore-rap-albums.html">horrorcore</a> to <a href="https://www.youtube.com/watch?v=MraJc0vyioI">spaza</a>, a subgenre that <a href="https://etd.uwc.ac.za/handle/11394/6966">emerged in Cape Town, South Africa</a>.</p>
<p>Dip hop is one of many styles of rap that have developed over the years. But it stands apart from other subgenres of hip-hop because rappers lay down rhymes in <a href="https://theconversation.com/explainer-what-is-sign-language-21453">sign languages</a> and craft music informed by their cultural experiences within the Deaf community. </p>
<h2>The birth of a musical movement</h2>
<p>As an <a href="https://www.ethnomusicology.org/page/AboutEthnomusicol">ethnomusicologist</a>, <a href="https://www.researchgate.net/profile/Katelyn-Best">I’ve followed</a> the development of dip hop since 2011, documenting how rappers have pioneered this art form while introducing outsiders, like myself, to <a href="https://www.nad.org/resources/american-sign-language/community-and-culture-frequently-asked-questions/">Deaf culture</a>.</p>
<p>In 2005, the rapper Warren “<a href="https://diphopwawa.com/home">Wawa</a>” Snipe came up with the term “DIP HOP” in <a href="https://www.nad.org/resources/american-sign-language/what-is-american-sign-language/">ASL</a> and English to classify a developing style of rap music within the Deaf community.</p>
<p>While artists of this style identify their music in different ways – some use labels like “deaf rap,” “deaf hip-hop” and “sign rap” – the designation “dip hop” goes beyond adding a qualifier to the broader musical genre of rap. Instead, it signals an independent style grounded in both hip-hop and Deaf culture. Like <a href="https://oxfordamerican.org/magazine/issue-115-winter-2021/a-brief-history-of-bounce">bounce</a>, trap and <a href="https://www.vulture.com/2022/08/what-is-the-sound-of-drill-rap.html">drill</a>, the label “dip hop” makes a greater distinction from being a variation of rap to a style that is heavily situated within Deaf culture and determined by Deaf aesthetics.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/2ZmASV0zK8s?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">‘Feel The Beat’ by Signkid (ft. Mr. Off Key).</span></figcaption>
</figure>
<p>In many ways, dip hop has followed <a href="https://theconversation.com/hip-hop-holiday-signals-a-turning-point-in-education-for-a-music-form-that-began-at-a-back-to-school-party-in-the-bronx-165525">a trajectory not unlike hip-hop</a>. </p>
<p>In the late 1990s and early 2000s, Deaf DJs and entertainment entrepreneurs organized DIY parties, nightlife events and social gatherings. These venues provided opportunities for rappers, DJs, dancers and other artists to begin to develop and explore their own style of hip-hop and connect with other rappers and DJs. </p>
<p>Cities with Deaf schools served as cultural hubs for musical networking. <a href="https://gallaudet.edu/about/">Gallaudet University</a> in Washington, D.C. and the <a href="https://www.rit.edu/ntid/">National Technical Institute for the Deaf</a> in Rochester, New York, have acted as significant sites of production within the U.S. by connecting deaf and hard of hearing students from all over the world.</p>
<p>Additionally, greater access to recording technology, video streaming sites and social media have given Deaf artists tools to create music and connect with other artists and fans.</p>
<h2>The many forms of dip hop</h2>
<p>While the incorporation of sign language is <a href="https://www.jstor.org/stable/26538859">a fundamental element of dip hop</a> – and remains at the forefront of defining this style – dip hop extends far beyond crafting original rap songs in sign language. </p>
<p>It involves musical expression that’s shaped through a Deaf cultural lens – songs that reorient mainstream notions of what can be considered music. At the same time, every artist has their own rapping style, with dip hop performances taking on a range of <a href="https://library.oapen.org/bitstream/handle/20.500.12657/51888/1/9783839456576.pdf#page=236">different forms and structures</a>. </p>
<p>For example, some dip hop artists work with both oral and manual languages to make their music accessible to hearing people. There are those who perform in both languages simultaneously, and others who <a href="https://www.youtube.com/watch?v=PbyBd87VpXI">prerecord their vocal track</a>, which plays in the background as they rap in sign language.</p>
<p>Some artists collaborate with interpreters. In “<a href="https://www.youtube.com/watch?v=w9E0X80oRUs">Vergiss mich nicht</a>,” artist Deaf Kat Night raps in <a href="https://www.unesco.de/en/culture-and-nature/intangible-cultural-heritage/german-sign-language">German sign language</a>, while the lyrics are interpreted orally in German. </p>
<p>Then there are those who collaborate with hearing or deaf DJs. “<a href="https://fb.watch/lcPvboC8YR/">Breaking Barrels</a>,” featuring DefStar, is just one of the many collaborations between Wawa and <a href="https://djnicar.beatstars.com/">DJ Nicar</a>. </p>
<p>Performances can also involve musical instruments. <a href="https://www.deafandloud.com/">Sean Forbes</a>, for example, performs with a live band while also rapping in ASL and English, an approach seen in his music video “<a href="https://youtu.be/lXchQ_uZhUY">Calm Like a Bomb</a>.” </p>
<p>Alternatively, there are rappers who create music for Deaf audiences and solely rap in sign languages. These songs, however, may still have auditory components, which often consist of artists composing their own beats or raising the volume of previously recorded songs to rap over. </p>
<p>Dip hop, like many styles of music, comes to life through live performance. Artists move across the stage with their hands flying through the air as audiences pulse to the rhythm of the blasting bass beat.</p>
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<figcaption><span class="caption">A performance by dip hop artists Wawa and Polar Bear at Gallaudet University’s 2015 DSP Bash.</span></figcaption>
</figure>
<p>Some artists further immerse their audiences in the musical experience by using specialized instruments and equipment such as subwoofers, objects that can conduct vibrations like balloons, or new forms of <a href="https://masschallenge.org/articles/haptic-technology/">haptic technology</a>, which refers to wearables, <a href="https://subpac.com/subpac-m2/">such as vests</a>, that channel sound vibrations. </p>
<p>Some artists also incorporate visuals into their performances through the use of video screens and <a href="https://www.cymaspace.org/audiolux/">sound-activated lights</a>.</p>
<h2>Breaking into the mainstream</h2>
<p>Dip hop artists have struggled to be acknowledged as musicians in their own right – to have their artistry be the focus of attention, rather than the fact that they’re deaf or hard of hearing.</p>
<p>That’s starting to change.</p>
<p>In 2009, Finnish rapper Marko “<a href="https://www.youtube.com/@signmarkprod">Signmark</a>” Vuoriheimo signed a record deal with Warner Music Finland and released “<a href="https://www.youtube.com/watch?v=oUtM8_DOVUI">Smells Like Victory</a>” and “<a href="https://www.youtube.com/watch?v=Q8YzAo2haKI">Speakerbox</a>” that same year.</p>
<p>This marked the first time in history a Deaf artist was signed to a major record label. The following year, Detroit-based rapper and National Technical Institute for the Deaf alumnus <a href="https://www.washingtonpost.com/entertainment/music/deaf-rapper-sean-forbes-makes-himself-joyfully-heard-on-the-hip-hop-scene/2015/01/25/15943fdc-a0f4-11e4-9f89-561284a573f8_story.html">Sean Forbes signed a contract</a> with WEB Entertainment and released the single “<a href="https://www.youtube.com/watch?v=E5l-2Jo14cQ">I’m Deaf</a>,” attracting mainstream attention to this style of rap.</p>
<figure class="align-center ">
<img alt="Man wearing sunglasses and a shirt that reads 'deaf and loud' holds his hands up to his ears." src="https://images.theconversation.com/files/539337/original/file-20230725-29-gqhuwh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539337/original/file-20230725-29-gqhuwh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=435&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539337/original/file-20230725-29-gqhuwh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=435&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539337/original/file-20230725-29-gqhuwh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=435&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539337/original/file-20230725-29-gqhuwh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=547&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539337/original/file-20230725-29-gqhuwh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=547&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539337/original/file-20230725-29-gqhuwh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=547&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sean Forbes poses during the 2014 National Association for the Deaf Breakthrough Awards Gala.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/deaf-rapper-sean-forbes-poses-during-the-national-news-photo/478567403?adppopup=true">Kevork Djansezian/Getty Images</a></span>
</figcaption>
</figure>
<p>And through the support of the Deaf community, hearing allies and fans, Forbes’ EP “<a href="https://www.youtube.com/watch?v=5JaUg94oazM">Little Victories</a>” reached No. 1 in the hip-hop category on iTunes and made it to the top 200 Billboard chart in 2020.</p>
<p>The following year, Wawa’s single “<a href="https://www.youtube.com/watch?v=wKduha4Tvog">LOUD</a>” was a top 20 dance track on iTunes. In 2022, Forbes and Wawa made history again as <a href="https://apnews.com/article/super-bowl-nfl-sports-arts-and-entertainment-mary-j-blige-fe4bf19eab4b5758f4f99eb3fcde5b70">the first ASL performers at a Super Bowl halftime show</a>.</p>
<p>In “<a href="https://www.facebook.com/wawasworld/videos/316257627136868/">Sign of the Times</a>,” Wawa raps: </p>
<pre class="highlight plaintext"><code> Sup beautiful people
I’m the Godpop of dip hop
Deaf eyes through hip hop
With signs for your eyes
Blow your mind and it won’t stop.
</code></pre>
<p>As dip hop evolves, it continues to push the boundaries of convention. In the spirit of hip-hop, dip hop rebels both musically and socially against cultural norms, breaking the mold and expanding possibilities for musical artistry. </p>
<p>Through their performances, dip hop artists not only subvert preconceived notions of music but also of Deaf culture and deafness, changing what it means for music to be heard.</p><img src="https://counter.theconversation.com/content/206825/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Katelyn Best does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Dip hop artists move across the stage, hands flying through the air, as audiences pulse to the rhythm of a blasting bass beat.Katelyn Best, Teaching Assistant Professor of Musicology, West Virginia UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1134362019-03-14T10:33:02Z2019-03-14T10:33:02ZFrom busking pigeons to head banging sea lions – can animals feel the beat?<figure><img src="https://images.theconversation.com/files/263871/original/file-20190314-28475-5pk40x.jpg?ixlib=rb-1.1.0&rect=0%2C6%2C4513%2C3546&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Funky pigeon.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/full-body-speed-racing-pigeon-bird-610981688?src=00gJLZ5ZiRxS7xMTU0rebQ-1-0">Stockphotomania/Shutterstock</a></span></figcaption></figure><p>A pigeon bopping along to a busker playing <a href="https://www.youtube.com/watch?v=Gg6sfTefD0U">Blurred Lines</a> by Robin Thicke and Pharrell Williams set Twitter abuzz recently. It’s certainly a catchy tune that I can’t help but tap my foot along to, but is that really what the pigeon is doing?</p>
<p>This pigeon seems to hop to the beat on one foot, or he may only have one leg. Either way, this would mean that it and other pigeons are capable of beat matching – thought to be a precursor to dancing and a uniquely human skill. <a href="https://www.npr.org/sections/krulwich/2014/04/01/297686709/the-list-of-animals-who-can-truly-really-dance-is-very-short-who-s-on-it?t=1552490010774">In order to beat match</a>, an animal must be able to match a complex pattern across a range of beats at different speeds (or tempos) and replicate the beat in a different format, known as a modality. In the pigeon’s case, this would mean hearing the music – sound is one modality – and dancing in response – movement is another modality. It would also need to predict when the beat is coming.</p>
<p>Many animals make repetitive, rhythmic movements, such as head bobbing in lizards and birds, chirping in crickets and frogs, and flashing in fireflies. When many of these animals come together, the rhythms of their songs and movements can align. This can be seen in fireflies, which <a href="https://nyaspubs.onlinelibrary.wiley.com/doi/full/10.1111/j.1749-6632.2009.04581.x">flash on and off together at the same time</a>. This is called rhythm entrainment. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1104299580265545728"}"></div></p>
<p>But this is simpler than beat matching. The fireflies flash in complex patterns and tempos, so it’s not just a simple rhythm but they aren’t capable of quickly changing between tempos. And the entrainment is all in the same modality – they see flashing and produce flashing, which could just be simple mimicry.</p>
<p>Another important criteria for beat matching is that humans can predict when the beat is coming. When I tap along to Blurred Lines, I tap directly on the beat because I predict when it’s coming. Many animals, such as rhesus monkeys, can change the timing of their beats so they’re roughly in time with music, but most of their taps will occur after the musical beat, and will <a href="https://www.ncbi.nlm.nih.gov/pubmed/19812296">not be as accurate as a human doing it</a>.</p>
<p>Many scientists think that <a href="https://www.jstor.org/stable/10.1525/mp.2006.24.1.99?seq=1#page_scan_tab_contents">only animals with vocal learning skills</a> should be able to tap along to a beat. These are animals that can learn complex vocal signals like human speech and mimic sounds. They include parrots, hummingbirds, elephants, some whales and dolphins, seals and bats. This is because scientists think that brain areas controlling sound-mimicking are likely also to be <a href="https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1001821#pbio.1001821-Patel2">involved in detecting a rhythm</a>.</p>
<h2>On camera</h2>
<p>There are some <a href="https://www.youtube.com/results?search_query=birds+dancing+to+music">convincing videos</a> of parrots bobbing along to a song, and being able to talk quite proficiently, too. A pigeon, however, is a non-vocal learner, so would it have the capacity to perceive the rhythm that it is supposedly bobbing along to? </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/CEQuDyuQFKE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>There is evidence that some non-vocal learners are able to tap along to beats, including sea lions and chimpanzees. As someone who spends time working with seals and sea lions, the study with <a href="https://www.ncbi.nlm.nih.gov/pubmed/23544769">Ronan the California sea lion</a> really caught my attention. </p>
<p>Researchers at the University of Santa Cruz in the US showed, after months of training, that Ronan could <a href="https://theconversation.com/dancing-seal-is-first-non-human-mammal-to-keep-a-beat-13182">nod her head to different tempo beats</a>, including those in Everybody (Backstreet’s Back) by the Backstreet Boys. This suggests that vocal learning isn’t essential for beat matching – careful training and exposure to beats and sounds can also help to develop this behaviour.</p>
<p>Ronan took a long time to learn this behaviour and did not show evidence for spontaneous beat matching – she couldn’t hear a rhythm and instinctively move to the beat, she had to be trained to do so. I was really interested in exploring whether other sea lions could do spontaneous beat matching. A previous study I worked on showed that sea lions made repetitive, cyclic, rhythmic movements <a href="https://www.ncbi.nlm.nih.gov/pubmed/25138923">during ball-balancing to keep the ball on their noses</a>. In particular, they did “keepie-uppies” or large head sways <a href="https://www.youtube.com/watch?v=bJyZafR382w">to keep the ball balanced</a>. I decided to focus on these movements and measure whether they changed pace with the tempo of a complex beat.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/6yS6qU_w3JQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>To design the beat, I partnered with <a href="https://www2.mmu.ac.uk/news-and-events/news/story/7323/">Jingyu Chen</a> – a composer from the Royal Northern College of Music. Jingyu designed some songs that matched the tempo of slow, medium and fast-moving head motions during ball-balancing. So far, it looks as if spontaneous beat matching does not happen in sea lions. Rather, with a lot of patience, training, fishy treats and exposure to music, some animals just appear to get there in the end.</p>
<p>Now let’s think back to the pigeon. It’s likely to be untrained and is not a vocal learner – you’ve never heard a pigeon “parrot” a sentence back to you – so it’s probably unable to perceive the beats in the music. In fact, on close inspection of the video, it looks as if the pigeon isn’t really bobbing in time to the music.</p>
<p>While the music is complex, the pigeon’s bobbing is a simple rhythm that is likely to fit a number of different tunes. Therefore, the pigeon in this video is unlikely to be dancing. Despite first appearances, it does not move like Jagger.</p>
<p>This does not mean that pigeons cannot bob along to music. They naturally make rhythmic head-bobbing behaviours, and may, like the sea lion, be able to bob along to music. They just need a bit of time, treats and exposure to music.</p><img src="https://counter.theconversation.com/content/113436/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robyn Grant does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Can animals find the beat in music and dance along?Robyn Grant, Senior Lecturer in Comparative Physiology & Behaviour, Manchester Metropolitan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/618122016-07-17T20:08:23Z2016-07-17T20:08:23ZHow a little mathematics can help create some beautiful music<figure><img src="https://images.theconversation.com/files/129765/original/image-20160708-30702-1ila8l3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Incredible rhythms when mathematics meets music.</span> <span class="attribution"><span class="source">Shutterstock/carlos castilla</span></span></figcaption></figure><p>Since the time of Pythagoras around 500 BCE, music and mathematics have had an intimate and mutually supportive relationship. </p>
<p>Mathematics has been used to tune musical scales, to design musical instruments, to understand musical form and to generate novel music. But what can mathematics say about one of the most common features of contemporary music – rhythmic loops?</p>
<p>Repeated rhythmic loops are an essential component of most electronic dance music and hip-hop, and also play an important role in rock, jazz, Latin and non-Western music. </p>
<p>Now, two mathematical models of rhythmic loops – made in a free software application called <a href="http://www.dynamictonality.com/xronomorph.htm">XronoMorph</a> – can be used to generate exciting new musical structures that would otherwise be hard to compose or perform.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/FgzLRzIM8rc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">XronoMorph: An Introduction.</span></figcaption>
</figure>
<h2>Rhythmic loops: Circles and polygons</h2>
<p>A natural geometrical characterisation of a periodic structure, such as a rhythmic loop, is as a circular arrangement of points. You can travel clockwise around a circle but inevitably you come back to where you started.</p>
<p>A common feature of rhythmic loops is that they are multilevel. For example, in Latin percussion, different instruments play different interlocking patterns that may or may not coincide. Such rhythms can be depicted by multiple polygons on the same circle.</p>
<p>A simple geometrical representation is to draw lines that make each of these independent levels into an independent polygon. In this way, a multilevel rhythm becomes a collection of inscribed polygons.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/129603/original/image-20160706-12750-1a6ue0r.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/129603/original/image-20160706-12750-1a6ue0r.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/129603/original/image-20160706-12750-1a6ue0r.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=147&fit=crop&dpr=1 600w, https://images.theconversation.com/files/129603/original/image-20160706-12750-1a6ue0r.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=147&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/129603/original/image-20160706-12750-1a6ue0r.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=147&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/129603/original/image-20160706-12750-1a6ue0r.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=185&fit=crop&dpr=1 754w, https://images.theconversation.com/files/129603/original/image-20160706-12750-1a6ue0r.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=185&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/129603/original/image-20160706-12750-1a6ue0r.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=185&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Clave (top) + Conga (bottom) rhythm in score notation.</span>
<span class="attribution"><span class="source">Andrew Milne</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/131348/original/image-20160721-8663-1ez9rxp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/131348/original/image-20160721-8663-1ez9rxp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/131348/original/image-20160721-8663-1ez9rxp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=602&fit=crop&dpr=1 600w, https://images.theconversation.com/files/131348/original/image-20160721-8663-1ez9rxp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=602&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/131348/original/image-20160721-8663-1ez9rxp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=602&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/131348/original/image-20160721-8663-1ez9rxp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=756&fit=crop&dpr=1 754w, https://images.theconversation.com/files/131348/original/image-20160721-8663-1ez9rxp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=756&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/131348/original/image-20160721-8663-1ez9rxp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=756&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Clave (red) + Conga (blue) rhythm as polygons.</span>
<span class="attribution"><span class="source">Andrew Milne</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>But which polygons?</h2>
<p>There are more than 17 trillion different rhythms, and that is only counting rhythms with three levels where every beat occurs at one of 16 distinct time locations (16 being a very common temporal subdivision in music).</p>
<p>But, realistically, only a small proportion of these are of musical interest. The trick is to find them.</p>
<p>Two mathematical principles – well-formedness and perfect balance – allow us to easily navigate two distinct rhythmic sub-spaces that are of musical interest, but hard to explore with traditional computational tools or notation.</p>
<h2>Well-formed polygons</h2>
<p><a href="https://www.researchgate.net/publication/299850277_Computational_creation_and_morphing_of_multilevel_rhythms_by_control_of_evenness">Well-formedness</a> elegantly generalises three properties commonly found in real-world multilevel rhythms:</p>
<ul>
<li><p>each rhythmic level comprises only a small number of distinct beat lengths, often only one or two;</p></li>
<li><p>each level’s beats are fairly evenly spaced in time – there aren’t sudden clusters of events followed by long gaps; and</p></li>
<li><p>the rhythmic levels are hierarchical – there is a slow and metrically dominant level; above this is a faster and weaker level that splits the previous level’s beats; above this is an even faster and weaker level that splits the previous level’s beats; and so on.</p></li>
</ul>
<p>Every level of a well-formed rhythm has two beat lengths: a long beat and a short beat. The length of a given beat is the time between its onset and the onset of the following beat.</p>
<p>A multilevel well-formed rhythm can then be fully defined by three numerical parameters: the numbers of long and short beats in the lowest level rhythm, and the ratio of the sizes of its long and short beats. </p>
<p>From these three numbers, an entire rhythmic hierarchy can be <a href="https://www.researchgate.net/publication/299850277_Computational_creation_and_morphing_of_multilevel_rhythms_by_control_of_evenness">calculated</a>, such that each level has no more than two beat lengths, each level arranges these beat lengths to make them as evenly spaced as possible and each successive level in the hierarchy is created by splitting the long beats of the level below. </p>
<p>Using XronoMorph, the above three parameters can be freely manipulated. The rhythmic hierarchy emerging from them often has great aesthetic appeal. Every level is related to every other level and is also intrinsically well-formed. Together, they create a somewhat self-similar and interwoven structure reminiscent of fractals.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/-UAECGZhbfU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A demonstration of how a well-formed hierarchy is built, and the effect of the lowest level’s beat-size ratio.</span></figcaption>
</figure>
<h2>Perfectly balanced polygons</h2>
<p><a href="https://www.researchgate.net/publication/278683682_Perfect_balance_A_novel_principle_for_the_construction_of_musical_scales_and_meters">Perfect balance</a> is a mathematical principle that can generalise polyrhythms, a type of rhythm commonly used in sub-Saharan African music.</p>
<p>Unlike well-formed rhythms and most Western rhythms, polyrhythms are not hierarchical. They are more like an alliance of different rhythmic levels, each of equal status.</p>
<p>In a polyrhythm, two or more levels, each comprising evenly spaced beats, are superimposed.</p>
<p>Geometrically, they are combinations of regular polygons like equilateral triangles, squares, regular pentagons, and so forth. In real-world polyrhythms, beats from all levels typically coincide at a single location in the period. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/cWcaxtgItzE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A standard 2:3:6 polyrhythm. For clarity, the hexagonal level is not shown.</span></figcaption>
</figure>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/SnQiL_XaqmQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A standard 3:4:12 polyrhythm. For clarity, the 12-gon level is not shown.</span></figcaption>
</figure>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/_s44fIgkUJE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A standard 3:5:15 polyrhythm. For clarity, the 15-gon level is not shown.</span></figcaption>
</figure>
<p>A notable feature of these polyrhythms is that the average position, or centre of gravity, of the circularly arranged beats is precisely at the centre of the circle. This property is defined as <a href="https://www.researchgate.net/publication/278683682_Perfect_balance_A_novel_principle_for_the_construction_of_musical_scales_and_meters">perfect balance</a>. </p>
<p>All regular polygons are perfectly balanced, so any combination of regular polygons is also perfectly balanced, and this is true regardless of the individual rotations of the polygons.</p>
<p>This allows an immediate generalisation of standard polyrhythms. The regular polygons can be independently rotated (time-shifted) so they never coincide. This is a musical feature that is, as far as we know, rarely exploited but which produces exciting rhythmic grooves.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/WQFKl2lZxfA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Perfectly balanced music constructed with independently rotated regular polygons: 2 digons, 3 squares, 1 heptagon. The polygons have been independently rotated so – unlike a standard polyrhythm – there is no single location at which they all coincide.</span></figcaption>
</figure>
<p>But perfect balance opens up yet another fascinating generalisation of standard polyrhythms. There are certain perfectly balanced shapes – irregular elemental polygons – that are not produced by a simple combination of regular polygons.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/129521/original/image-20160706-12727-7puub2.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/129521/original/image-20160706-12727-7puub2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/129521/original/image-20160706-12727-7puub2.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/129521/original/image-20160706-12727-7puub2.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/129521/original/image-20160706-12727-7puub2.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/129521/original/image-20160706-12727-7puub2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/129521/original/image-20160706-12727-7puub2.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/129521/original/image-20160706-12727-7puub2.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An irregular elemental polygon: 1 triangle + 1 pentagon - 1 digon. Only the labelled vertices are sounded.</span>
<span class="attribution"><span class="source">Andrew Milne</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/129522/original/image-20160706-12722-q3apcs.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/129522/original/image-20160706-12722-q3apcs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/129522/original/image-20160706-12722-q3apcs.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=479&fit=crop&dpr=1 600w, https://images.theconversation.com/files/129522/original/image-20160706-12722-q3apcs.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=479&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/129522/original/image-20160706-12722-q3apcs.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=479&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/129522/original/image-20160706-12722-q3apcs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=602&fit=crop&dpr=1 754w, https://images.theconversation.com/files/129522/original/image-20160706-12722-q3apcs.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=602&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/129522/original/image-20160706-12722-q3apcs.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=602&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An irregular elemental polygon: 2 digons + 3 pentagons - 3 digons - 2 triangles. Only the labelled vertices are sounded.</span>
<span class="attribution"><span class="source">Andrew Milne</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Intriguingly, such polygons are constructed by summing differently rotated positively-weighted and negatively-weighted regular polygons. When a positively-weighted vertex and a negatively-weighted vertex coincide they cancel out.</p>
<p>Legal patterns are produced when no negative weights are left behind. So, although we never hear these negative beats directly, they have a ghostly impact by cancelling out some of the positive beats.</p>
<p>In XronoMorph, a wide choice of regular and irregular elemental polygons can be combined and independently rotated, creating a fascinating subspace of generalised polyrhythms.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/xNiFORnCYdI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Perfectly balanced music constructed with regular and irregular elemental polygons.</span></figcaption>
</figure>
<h2>XronoMorph</h2>
<p>We developed the rhythmic loop generator <a href="https://www.researchgate.net/publication/302345911_XronoMorph_Algorithmic_generation_of_perfectly_balanced_and_well-formed_rhythms">XronoMorph</a> to <a href="https://www.youtube.com/c/xronomorph">demonstrate these principles</a>, hoping it might inspire musicians and music enthusiasts to create novel and interesting rhythms that would be hard to play manually or to otherwise compose. </p>
<p>Simple and attractive software interfaces can also transform a need for expert knowledge into a willingness to intuitively interrogate the interface. In this way, we also hope it will encourage musical engagement, with potential application in music education by allowing visual exploration of complex rhythmic patterns.</p>
<p>Early reaction from musicians and composers has been highly enthusiastic with comments such as “This is an inspired design – truly musical”, “the most interesting and inventive new app around” and “this really helps me better understand and create beats”.</p>
<p>This lends support to the long-held notion that there is a profound connection between mathematics and music, and that a little mathematics can help create some beautiful music.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/129525/original/image-20160706-12708-zkml1o.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/129525/original/image-20160706-12708-zkml1o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/129525/original/image-20160706-12708-zkml1o.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=371&fit=crop&dpr=1 600w, https://images.theconversation.com/files/129525/original/image-20160706-12708-zkml1o.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=371&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/129525/original/image-20160706-12708-zkml1o.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=371&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/129525/original/image-20160706-12708-zkml1o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=466&fit=crop&dpr=1 754w, https://images.theconversation.com/files/129525/original/image-20160706-12708-zkml1o.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=466&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/129525/original/image-20160706-12708-zkml1o.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=466&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">XronoMorph screenshot.</span>
<span class="attribution"><span class="source">Andrew Milne</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure><img src="https://counter.theconversation.com/content/61812/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew J. Milne is affiliated with Dynamic Tonality, a loosely organised collective of researchers and fellow travellers who host a website and build software for facilitating interaction with experimental music. The software application described in this article is free, but users can make a donation to support the costs of hosting the website and to support further software development.</span></em></p><p class="fine-print"><em><span>Dr. Steffen A. Herff does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Mathematics can help musicians and music enthusiasts create rhythms that would be hard to play manually or to otherwise compose.Andrew J. Milne, Postdoctoral Research Fellow in Music Cognition and Computation, Western Sydney UniversityDr. Steffen A. Herff, PhD candidate, Memory and Music Perception, Western Sydney UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/563542016-05-06T02:00:26Z2016-05-06T02:00:26ZRhythm on the brain, and why we can’t stop dancing<figure><img src="https://images.theconversation.com/files/120937/original/image-20160503-19517-1rzrp3w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Some of us can't help moving to a beat.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Music and dance are far from idle pastimes. They are universal forms of expression and deeply rewarding activities that fulfil diverse social functions. Both feature in all the world’s cultures and throughout history. </p>
<p>A common feature of music and dance is rhythmic movement, which is often timed with a regular pulse-like beat. But the human capacity for rhythm presents something of a puzzle. </p>
<p>Even though rhythmic coordination seems fundamental to human nature, people vary widely in ability. Some have the machine-like precision of Michael Jackson, others are closer to the case of <a href="http://www.smithsonianmag.com/smart-news/cant-clap-beat-you-might-be-beat-deaf-180953286/?no-ist">“beat-deaf” Mathieu</a>. </p>
<p>What are the underlying causes of these individual differences? By looking at the way the brain responds to rhythm, we can begin to understand why many of us can’t help but to move to a beat.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/9fHX54lhGEg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Sometimes the dancing is infectious.</span></figcaption>
</figure>
<h2>Power of rhythm</h2>
<p>Rhythm is a powerful force. It can regulate mood, ranging from the arousing effect of pounding war drums to the pacifying effect of gently rocking a baby. It can even induce altered states of consciousness, as in spiritual rituals and shamanic traditions involving <a href="http://cercor.oxfordjournals.org/content/early/2015/06/23/cercor.bhv137.abstract">trance</a>.</p>
<p>Rhythm and music can also be used for therapeutic purposes in the rehabilitation of conditions characterised by motor impairment, such as stroke and Parkinson’s disease. </p>
<p>Even more fundamentally, rhythmic skills displayed in the context of music and dance may have been essential to our evolution as a <a href="http://journal.frontiersin.org/article/10.3389/fpsyg.2014.01118/full">species</a>. </p>
<p>In The Descent of Man (1871), Charles Darwin <a href="http://darwin-online.org.uk/content/frameset?pageseq=354&itemID=F937.2&viewtype=text">mused that</a>:</p>
<blockquote>
<p>it appears probable that the progenitors of man, either the males or females or both sexes, before acquiring the power of expressing their mutual love in articulate language, endeavoured to charm each other with musical notes and rhythm.</p>
</blockquote>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/OgzdDp5qfdI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">We seem naturally equipped to learn how to move to rhythm.</span></figcaption>
</figure>
<p>Rhythmically coordinated body movements may function similarly to fuel sexual attraction by providing an “honest” signal (one that can’t be faked) of an individual’s <a href="http://rsbl.royalsocietypublishing.org/content/early/2010/09/06/rsbl.2010.0619">health and fitness</a>. </p>
<p>Outside the competitive arena of finding a mate, coordinating with others through music and dance facilitates <a href="http://journal.frontiersin.org/article/10.3389/fpsyg.2014.01096/full">social cohesion</a> by promoting interpersonal bonding, trust, and cooperation. </p>
<p>These prosocial effects of music and dance may have contributed to the flourishing of human culture by preventing the disintegration of early societies into antisocial mobs. </p>
<p>Today, they remain potent enough to be relied on, even in maximum security <a href="https://www.youtube.com/watch?v=hMnk7lh9M3o">prisons</a>.</p>
<h2>Entrainment</h2>
<p>But if music and dancing are so universal, why are some people simply unable to hold a rhythm?</p>
<p>The key to answering this question lies in how the human brain locks onto rhythms in the external environment, and how this process of “neural entrainment” supports the coordination of body movements. </p>
<p>Neural entrainment occurs when regular sensory input, like music with a clear beat, triggers periodic bursts of synchronised brain activity. This periodic activity can continue independently of external rhythmic input due to interactions between already excited neurons. It is as if they expect the sensory input to continue. </p>
<p>Entrainment can thus enhance processing of incoming information by allocating neural resources to the right place at the right time. When performing or dancing to music, entrainment allows the timing of upcoming beats to be predicted.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/120934/original/image-20160503-19529-1i10f6a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/120934/original/image-20160503-19529-1i10f6a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/120934/original/image-20160503-19529-1i10f6a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=255&fit=crop&dpr=1 600w, https://images.theconversation.com/files/120934/original/image-20160503-19529-1i10f6a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=255&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/120934/original/image-20160503-19529-1i10f6a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=255&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/120934/original/image-20160503-19529-1i10f6a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=321&fit=crop&dpr=1 754w, https://images.theconversation.com/files/120934/original/image-20160503-19529-1i10f6a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=321&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/120934/original/image-20160503-19529-1i10f6a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=321&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sometimes we just have to move.</span>
<span class="attribution"><span class="source">Scott Robinson/Flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>A recent study on <a href="http://www.nature.com/articles/srep20612">individual differences in rhythmic skill</a> identified relationships between the strength of neural entrainment and the capacity to synchronise movements with musical rhythms. </p>
<p>We measured entrainment to the underlying beat in two types of rhythm using electroencephalography (EEG), a technique where electrical signals reflecting neural activity are recorded via electrodes placed on the head. </p>
<p>One rhythm had a regular beat marked by periodically occurring sound onsets. The other was a relatively complex and jazzier “syncopated” rhythm in which sound onsets were not present on all beats: some were marked by silence. </p>
<p>Results indicated that the strength of neural entrainment was related to people’s ability to move in synchrony with the beat. Individuals with strong neural responses were more accurate at tapping a finger in time with the beat of the two rhythms. </p>
<p>We also found individual differences in brain responses to the two rhythms. While some individuals showed a large difference between strength of entrainment for the regular rhythm versus the syncopated rhythm, others showed only a small difference. </p>
<p>In other words: some people required external physical stimulation to perceive the beat, whereas others were able to generate the beat internally. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Np8-7MLt5Ro?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">All cultures around the world and throughout history have engaged in dance.</span></figcaption>
</figure>
<p>Remarkably, people who were good at internally generating beats also performed well on a synchronisation task that required them to predict tempo changes in musical sequences. </p>
<p>So the capacity for internal beat generation turns out to be a reliable marker of rhythmic skill. This adds new meaning to Miles Davis’ reported maxim that “in music, silence is more important than sound”.</p>
<p>But we still don’t know why individual differences in the strength of neural entrainment occur in the first place. They may reflect the efficiency of neural responses at early levels of auditory processing, such as brainstem responses. Or the degree of connectivity between higher-level auditory and motor cortical regions. </p>
<p>Another open question is whether rhythmic skills can be boosted by recent advances in neuroscience. Brain stimulation techniques that induce neural synchrony at specific frequencies provide a promising method for enhancing entrainment and thereby improving an individual’s capacity for rhythm.</p><img src="https://counter.theconversation.com/content/56354/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Keller receives funding from the Australian Research Council. </span></em></p>The reason why some of us can’t help but to dance, and others can’t hold a beat, might lie in the brain.Peter Keller, Professor of Cognitive Science, Western Sydney UniversityLicensed as Creative Commons – attribution, no derivatives.