Second Monday Music: Influential rhythms

The significance of musical entrainment

By André Duvall

[Adapted from a paper in the Psychology of Music]

We have all had the experience of listening to a piece of music, enjoying it, and finding ourselves tapping our feet to the beat, sometimes without consciously deciding to do so. Likewise, as we walk down the sidewalk at a comfortable pace, our arms naturally tend to sway in some form of regular motion directly related to the rhythmic motion of our legs. Musicians are aware of the importance during rehearsal and performance situations of synchronizing our internal rhythmic pulse with those of the conductor or other performers. All of these situations illustrate the concept of human rhythmic entrainment. While these examples may seem to be obvious everyday phenomena, the idea of entrainment has significant implications for understanding how humans experience music, and how music can influence human health.

Entrainment, in layman’s terms, is a process in which two independently operating rhythms interact with each other, and upon interaction, begin to synchronize their rhythms in some fashion and to some degree. Rhythmic patterns may recur at regular intervals; the literature often describes the interacting items that produce the rhythms as “oscillators” that lock in to “a common phase or periodicity.” These oscillators can be inanimate stimuli such as musical instruments or a clock ticking on the wall, biological phenomena such as heartbeat and brain waves, or a human voice producing a melody. A wealth of literature explores entrainment from several disciplines, but there exists a much smaller amount of study on entrainment specifically focused on music. However, certain studies in other disciplines indirectly involve music; the findings reveal how musical entrainment may exert great influence on music perception and social functioning; these studies provide a foundation and motivation for further study of musical entrainment. Furthermore, the existing literature that does focus on music reveals practical and successful applications of entrainment in the realm of human disease and wellness. This article provides a general overview and introduction to studies in musical entrainment as it relates to musical perception, socialization, and human health.
    Studies in neuroscience reveal that most activities in the human brain require groups of neurons to operate in synchrony; often they also exhibit recurring patterns (i.e., periodicity). The neural pathways that integrate outside stimulation with physical movement, referred to as “sensory-motor coordination,” are directly influenced by these oscillating brain activities. Outside stimuli, such as a pulsating strobe light, are known to create entrainment with some of these brain oscillations. Biologists have contributed much literature on periodic rhythms, such as the circadian rhythms of living creatures, and the occurrence of entrainment of physiological rhythms in all plants and animals, such as crickets chirping together in chorus and plants adjusting their physical position during daylight hours.

A common theme among the biological studies is that while stability through entrainment does not always mean good health for an organism, for a given entrainment situation there tends to be relatively healthier ways to be entrained, such as the proper use of a pacemaker in a human heart, and less desirable ways to be entrained, such as stable brain waves observed in epilepsy patients. In some cases, the lack or presence of entrainment may put the organism at risk for pathology: human diseases such as Parkinson’s Disease and autism, for example, result from a transition from an optimal degree of entrainment to a less optimal one. Healthy levels of entrainment may also create a sense of contentment, as when members of an ensemble strive to play in time together. Combining the findings of neurology and biology in general, a relatively new area of study has emerged: the use of music as an auditory stimulus to entrain with periodic activity in the human brain (much like the optical strobe light stimuli), which can have effect on motor functioning and emotion. While much more study is needed in the area of music to strengthen existing theories, the results thus far support a direct connection between music and entrainment of brain activity, which then influences other bodily processes.
    Several well-structured clinical experiments have demonstrated that musical entrainment has positive effects on the recovery of patients with Parkinson’s Disease and victims of hemiparetic stroke. Expanding upon the contributions of neuroscience, these studies discovered that rhythms present in neural networks concerned with motor functioning and auditory association can entrain with auditory stimuli. Most of the studies used rhythmic auditory stimulation, a technique in which a percussive rhythmic pattern or a musical selection was matched at or near the baseline walking speed of the patient. Results from initial and repeated studies indicated significant improvement of the gait, vertical balance, and stride length of Parkinson’s Disease and stroke patients with various speeds of stimulation. These improvements coincided with changes in corresponding brain wave amplitudes. The results withstood repeated trials with different samples, and the benefits of entrainment therapy lasted for several weeks after therapy was discontinued. Further research is needed to explore the effects of rhythmic auditory stimulation on children with cerebral palsy, but the preliminary results look promising.

Lauren Dimaio conducted case studies on the effects of music entrainment as part of music therapy treatment for hospice patients who were experiencing pain. Her work illustrates an example of the current exploration of the practical applications of musical entrainment in non-experimental settings. Dimaio expands entrainment to include shared emotional empathy and understanding of pain between therapist and patient. In each case study, Dimaio strove to improvise a musical setting which as accurately as possible represented the patient’s current level of pain. This was accomplished by listening to and asking for feedback from the patient in a variety of ways, and experimenting with various musical timbres and textures. Gradually, Dimaio changed the “pain” music to “healing” music, always adjusting the music according to the responses and musical tastes of the patient. If at any point the patient became un-entrained from the music, Dimaio would return to a previous degree of pain music. Although the procedure required much patience and time, in each case study, the patients rated their final level of pain as significantly lower than before starting the entrainment therapy.
    While her results are exciting and intriguing, they need more follow-up. As case studies, they represent a very small sample size, and the therapy was administered by the same therapist in each case. Furthermore, there was no experimental setup with control of variables as in the studies cited earlier on autism and Parkinson’s. Follow up studies could also elaborate more on the specific characteristics of pain and comfort music, since the present study was based on one therapist’s undisclosed musical interpretations.

Social psychologists have explored the idea that most human behavior is periodic or rhythmical to some degree; most of these rhythms are innate, and they tend to entrain when individuals interact with each other. Studies reveal rhythms in communication through speech and gesture; Nigel Osborne describes musical rhythm as an “externalization” of inner biological rhythms. In keeping with the biological model, studies also reveal that there is an optimal level of entrainment in efficient social interaction. This has many social implications. For example, people who are not able to entrain to language cues as well as others in a group are easily identified as foreigners. In music, knowledge of certain musical ideas of a given culture allows for a better understanding of the meaning of that culture’s music; future studies that identify the “ideal” level of entrainment of musical cues can help define a culture’s musical style.
    Ethnomusicologists have explored a bodily-movement basis of rhythmic entrainment. Alan Lomax was one of the first ethnomusicologists to study rhythm as fundamentally social in nature, exploring how music can give groups an identity by facilitating cultural rituals, transfer of information, and a form of expression. John Blacking’s theories coincide with the recurring theme of optimal entrainment levels creating a sense of pleasure: he posited that the sense of rapport that results from social musical activities is directly related to the synchronizing of musical rhythms.

Cognitive psychology shows that our perceptions, focus of attention, and expectations when listening to music are all influenced by entrainment; studies also show that humans have a degree of self-control over how they entrain to music they are hearing. This is significant, because it presents music experience as a two-way street, a relationship between the musical stimulus and the receiver, rather than simply a pre-formed musical stimulus reaching all receivers in a set way. Let us consider perception first. Two people listening to the same performance may perceive rhythms differently, because they have acquired different knowledge structures (schemas) based on different past experiences. One person may associate a given rhythm pattern with previously heard pieces and emotions tied to those pieces, while the other person may not recognize certain intricacies of rhythm because they haven’t had as much exposure to those rhythms.
    Expectations can be influenced by entrainment. Humans have a natural propensity towards recognizing a regular pulse in music. Mari Riess Jones and her colleague’s studies on entrainment have shown that music that is “free” from regular meter and pulse can still create entrainment, as listeners tend to perceive a “centered or median period length.” This is important because it illustrates the flexibility and adaptability of human mental entrainment. When expectations while listening to music are thwarted (or when the entrainment pattern is broken), humans can adapt their expectations and re-synchronize with the changes in the music. This may explain why a well-executed rubato does not cause the listener to feel discord in rhythmic pulse. Rubato is a musical technique in which the performer takes freedom with the rhythm, tempo, and phrasing for expressive purposes; rubato must be used with discretion, or it can easily be overdone. Entrainment need not be limited to rigid or metronomic rhythmic experiences. This also corroborates the previously mentioned idea that healthy levels of entrainment (which are not necessarily perfect levels) create a sense of contentment.
    Attention itself can also be considered as a process that can be entrained (incidentally, this demonstrates an example of how music as a discipline has expanded the definition of entrainment from previous studies). It has been shown that where one focuses attention when listening to music is based both on volition/personal desires and on the external stimulus. A practical application of this can be seen in learning to relate to foreign music: Research shows that in music that lacks metric organization, such as Indian alap improvisations, attention tends to entrain toward shorter time intervals, as opposed to “future-oriented” attention characterized by metered music . Thus, when listening to unmetered music, one might have a more enjoyable experience if one focuses on the various nuances of pitch, quality, and dynamics at any given moment rather than try to discover implications of longer breadth in the music, such as predictable phrases, for example. A larger implication of this study is that is suggests a potential cross-cultural benefit: future musical entrainment studies may clarify what constitutes cultural differences in music, and perhaps may help ease the attempts of outsiders to assimilate into a new musical culture.

The study of entrainment has a broad history across a range of disciplines. The results of these studies provide a strong framework for exploring the benefits of human musical entrainment, an area that warrants much more investigation. With the improvement of the quality of life for patients afflicted with certain pathologies, and with the window of insight into the perception of music within and across cultures, the study of entrainment will certainly continue to reap benefits for the human condition.
_______________
Copyright © 2013 by André Duvall

Please comment