The influence of external and internal motor processes on human auditory rhythm perception

Musical rhythm is composed of organized temporal patterns, and the processes underlying rhythm perception are found to engage both auditory and motor systems. Despite behavioral and neuroscience evidence converging to this audio-motor interaction, relatively little is known about the effect of specific motor processes on auditory rhythm perception. This doctoral thesis was devoted to investigating the influence of both external and internal motor processes on the way we perceive an auditory rhythm. The first half of the thesis intended to establish whether overt body movement had a facilitatory effect on our ability to perceive the auditory rhythmic structure, and whether this effect was modulated by musical training. To this end, musicians and non-musicians performed a pulse-finding task either using natural body movement or through listening only, and produced their identified pulse by finger tapping. The results showed that overt movement benefited rhythm (pulse) perception especially for non-musicians, confirming the facilitatory role of external motor activities in hearing the rhythm, as well as its interaction with musical training. The second half of the thesis tested the idea that indirect, covert motor input, such as that transformed from the visual stimuli, could influence our perceived structure of an auditory rhythm. Three experiments examined the subjectively perceived tempo of an auditory sequence under different visual motion stimulations, while the auditory and visual streams were presented independently of each other. The results revealed that the perceived auditory tempo was accordingly influenced by the concurrent visual motion conditions, and the effect was related to the increment or decrement of visual motion speed. This supported the hypothesis that the internal motor information extracted from the visuomotor stimulation could be incorporated into the percept of an auditory rhythm. Taken together, the present thesis concludes that, rather than as a mere reaction to the given auditory input, our motor system plays an important role in contributing to the perceptual process of the auditory rhythm. This can occur via both external and internal motor activities, and may not only influence how we hear a rhythm but also under some circumstances improve our ability to hear the rhythm.Musikalische Rhythmen bestehen aus zeitlich strukturierten Mustern akustischer Stimuli. Es konnte gezeigt werden, dass die Prozesse, welche der Rhythmuswahrnehmung zugrunde liegen, sowohl motorische als auch auditive Systeme nutzen. Obwohl sich für diese auditiv-motorischen Interaktionen sowohl in den Verhaltenswissenschaften als auch Neurowissenschaften übereinstimmende Belege finden, weiß man bislang relativ wenig über die Auswirkungen spezifischer motorischer Prozesse auf die auditive Rhythmuswahrnehmung. Diese Doktorarbeit untersucht den Einfluss externaler und internaler motorischer Prozesse auf die Art und Weise, wie auditive Rhythmen wahrgenommen werden. Der erste Teil der Arbeit diente dem Ziel herauszufinden, ob körperliche Bewegungen es dem Gehirn erleichtern können, die Struktur von auditiven Rhythmen zu erkennen, und, wenn ja, ob dieser Effekt durch ein musikalisches Training beeinflusst wird. Um dies herauszufinden wurde Musikern und Nichtmusikern die Aufgabe gegeben, innerhalb von präsentierten auditiven Stimuli den Puls zu finden, wobei ein Teil der Probanden währenddessen Körperbewegungen ausführen sollte und der andere Teil nur zuhören sollte. Anschließend sollten die Probanden den gefundenen Puls durch Finger-Tapping ausführen, wobei die Reizgaben sowie die Reaktionen mittels eines computerisierten Systems kontrolliert wurden. Die Ergebnisse zeigen, dass offen ausgeführte Bewegungen die Wahrnehmung des Pulses vor allem bei Nichtmusikern verbesserten. Diese Ergebnisse bestätigen, dass Bewegungen beim Hören von Rhythmen unterstützend wirken. Außerdem zeigte sich, dass hier eine Wechselwirkung mit dem musikalischen Training besteht. Der zweite Teil der Doktorarbeit überprüfte die Idee, dass indirekte, verdeckte Bewegungsinformationen, wie sie z.B. in visuellen Stimuli enthalten sind, die wahrgenommene Struktur von auditiven Rhythmen beeinflussen können. Drei Experimente untersuchten, inwiefern das subjektiv wahrgenommene Tempo einer akustischen Sequenz durch die Präsentation unterschiedlicher visueller Bewegungsreize beeinflusst wird, wobei die akustischen und optischen Stimuli unabhängig voneinander präsentiert wurden. Die Ergebnisse zeigten, dass das wahrgenommene auditive Tempo durch die visuellen Bewegungsinformationen beeinflusst wird, und dass der Effekt in Verbindung mit der Zunahme oder Abnahme der visuellen Geschwindigkeit steht. Dies unterstützt die Hypothese, dass internale Bewegungsinformationen, welche aus visuomotorischen Reizen extrahiert werden, in die Wahrnehmung eines auditiven Rhythmus integriert werden können. Zusammen genommen, 5 zeigt die vorgestellte Arbeit, dass unser motorisches System eine wichtige Rolle im Wahrnehmungsprozess von auditiven Rhythmen spielt. Dies kann sowohl durch äußere als auch durch internale motorische Aktivitäten geschehen, und beeinflusst nicht nur die Art, wie wir Rhythmen hören, sondern verbessert unter bestimmten Bedingungen auch unsere Fähigkeit Rhythmen zu identifizieren

The impact of the bass drum on human dance movement

The present study aims to gain better insight into the connection between music and dance by examining the dynamic effects of the bass drum on a dancing audience in a club-like environment. One hundred adult participants moved freely in groups of five to a musical sequence that comprised six songs. Each song consisted of one section that was repeated three times, each time with a different sound pressure level of the bass drum. Hip and head movements were recorded using motion capture and motion sensing. The study demonstrates that people modify their bodily behavior according to the dynamic level of the bass drum when moving to contemporary dance music in a social context. Participants moved more actively and displayed a higher degree of tempo entrainment as the sound pressure level of the bass drum increased. These results indicate that the prominence of the bass drum in contemporary dance music serves not merely as a stylistic element; indeed, it has a strong influence on dancing itself

The Neural Mechanisms of Musical Rhythm Processing: Cross-Cultural Differences and the Stages of Beat Perception

Music is a universal human behaviour, is fundamentally temporal, and has unique temporal properties. This thesis presents research on the cognitive neuroscience of the temporal aspects of music: rhythm, beat, and metre. Specifically, this work investigates how cultural experience influences behavioural and neural measures of rhythm processing, and the different neural mechanisms (with particular interest in the role of the striatum) that underlie different stages of beat perception, as musical rhythms unfold. Chapter 1 presents an overview of the existing literature on the perceptual, cognitive, and neural processing of rhythm, including the entrainment of neural oscillations to rhythm and the neuroanatomical substrates of rhythm perception. Chapter 2 presents research on cross-cultural differences in the perception and production of musical rhythm and beat. Here, East African and North American participants performed three tasks (beat tapping, rhythm discrimination, and rhythm reproduction) using rhythms from East African and Western music. The results indicate an influence of culture on beat tapping and rhythm reproduction, but not rhythm discrimination. Chapter 3 presents electroencephalographic (EEG) research on cross-cultural differences in neural entrainment to rhythm and beat. The degree to which neural oscillations entrained to the different regular ‘metrical levels’ of rhythms differed between groups, suggesting an influence of culture. Moreover, across all participants, the proportion of trials in which different rates were tapped was correlated with the degree of neural entrainment to those rates. Chapter 4 presents functional magnetic resonance imaging (fMRI) research on the different neural mechanisms that underlie the different stages of beat perception (finding, continuation, and adjustment). Distinct regions of the striatum (dorsal vs. ventral putamen) were active to different extents in beat finding and adjustment, respectively. Activity in other regions (including the cerebellum, parietal cortex, supplementary motor area, and insula) also differed between stages. Additionally, when rhythms were metrically incongruent (polyrhythmic), additional activity was found in superior temporal gyri and the insula. Chapter 5 presents a general discussion of Chapters 2-4 in the context of the existing literature, limitations, and broader interpretations of how these results relate to future directions in the field

Instructed versus spontaneous entrainment of running cadence to music tempo

Matching exercise behavior to musical beats has been shown to favorably affect repetitive endurance tasks. In this study, our aim was to explore the role of spontaneous versus instructed entrainment, focusing on self‐paced exercise of healthy, recreational runners. For three 4‐min running tasks, 33 recreational participants were either running in silence or with music; when running with music, either no instructions were given to entrain to the music, or participants were instructed to match their running cadence with the tempo of the music. The results indicated that less entrainment occurred when no instruction to match the exercise with the musical tempo was provided. In addition, similar to the condition without music, lower speeds and shorter step lengths were observed when runners were instructed to match their running behavior to the musical tempo when compared with the condition without such instruction. Our findings demonstrate the impact of instruction on running performance and stress the importance of intention to entrain running behavior to musical beats

Raw Cognition: Rhythms as Dynamic Constraints

There is increasing evidence that the rhythmic interactions between intrinsic oscillators both in the body and in the brain play a constitutive role in cognition. However, the mechanisms and extent of these interactions are yet to be fully understood. In this article, I will contend that a notion of rhythm as an open entrainment can be useful for enactive approaches to different aspects of cognition. It allows us to think of the different oscillators that we find in the body, the brain, and the environment as nested dynamic constraints that through neuronal and non-neuronal interactions tie together the different domains while retaining their specific functions

Oromotor Kinematics of Speech In Children and the Effect of an External Rhythmic Auditory Stimulus

The purpose of this study was to determine the effect of an external auditory rhythmic stimulus on the kinematics of the oromotor musculature during speech production in children and adults. To this effect, the research questions were: 1) Do children entrain labiomandibular movements to an external auditory stimulus? 2) Does the ability to entrain labiomandibular movements to an external auditory stimulus change with age? 3) Does an external auditory stimulus change the coordination and stability of the upper lip, lower lip, and jaw when producing speech sounds? The oromotor kinematics of two groups of children, age eight to ten (n = 6) and eleven to fourteen (n = 6), were compared to the oromotor kinematics of adults (n = 12) while producing bilabial syllables with and without an external auditory stimulus. The kinematic correlates of speech production were recorded using video-based 4-dimensional motion capture technology and included measures of upper lip, lower lip and jaw displacement and their respective derivatives. The Spatiotemporal Index (a single number indication of motor stability and pattern formation) and Synchronization Error (a numerical indication of phase deviations) were calculated for each participant within each condition. There were no statistically significant differences between age groups for the Spatiotemporal Index or for Synchronization Error. Results indicated that there were statistically significant differences in the Spatiotemporal Index for condition; with Post-hoc tests indicating that the difference was between the first condition (no rhythm) and the second condition (self-paced rhythm). Results indicated that both child groups were able to synchronize to an external auditory stimulus. Furthermore, the older child group was able to establish oromotor synchrony with near-adult abilities

Investigating how neural entrainment relates to beat perception by disentangling the stimulus-driven response

Beat perception – the ability to perceive a steady pulse in music – is nearly ubiquitous in humans, but the neural mechanisms underlying this ability are unknown. A growing number of electroencephalography (EEG) studies suggest that beat perception is related to neural entrainment, a phenomenon in which cyclic changes in the excitability of populations of neurons synchronize with a rhythmic stimulus. However, the relationship between acoustically-driven and entrainment-driven neural activity is unclear. This thesis presents EEG research that extends our understanding neural entrainment is related to beat perception by characterizing, equating, and finally removing the stimulus-driven response in the neural signal isolating the entrainment-driven responses. Chapter 1 presents a general overview of how neural entrainment may relate to beat perception, the common methods of measuring neural entrainment, and current debates in the literature about how best to account for the stimulus-driven response in the neural signal and also what the neural power spectrum reflects. Chapter 2 presents research on how perceptual and acoustic factors in auditory stimuli influence neural spectral power in a series of experiments in which beat strength, tone duration, and onset/offset ramp duration were manipulated. The results suggest that both perceptual and acoustic factors influence neural spectral power, and that accounting for the stimulus-driven response in the neural spectrum is more complicated than previously assumed. Chapter 3 presents research on how power and phase of the neural signal relate to beat strength and beat location while controlling the stimulus-driven response. The results indicated a relationship between neural entrainment and beat strength, and also, between oscillatory phase and beat location. Chapter 4 presents research on the potential neural mechanisms of beat perception by examining neural activity during a silent immediately after rhythm perception for testing for ongoing, oscillatory activity. The results, although not statistically robust, suggest that entrained activity continues into silence, indicating a relationship between neural entrainment and beat perception. Chapter 5 presents a general discussion of Chapters 2-4 in the context of the existing literature, limitations, and broader interpretations of how these results relate to future directions in the field

A Study of Music: Music Psychology, Music Therapy, and Worship Music

There are three specific fields related to music: the psychology of Music and how it affects human brain and functions, the methodology of Music Therapy and how it affects individuals undergoing treatment, and the psychological effects of Worship Music and how it can be used in music therapy. Music therapy is a growing field in which the therapeutic outcomes greatly benefit the patients. The overall purpose is to create a greater understanding of music and music therapy in order to a provide a system for introducing group worship services into music therapy to ultimately bring spiritual healing to individuals