Rhythm in speech and music
“May I have your attention please?”
Do you remember back in 2000, when Marshall Mathers, better known as Eminem, tried to find out who “The Real Slim Shady” was? You might have known immediately that he was referring to his alter ego, but would you have considered yourself a Slim Shady? If so, you were right.
In their latest series of experiments, published in the journals Proceedings of the Royal Society B and Hearing Research, Manon Grube of the University of Newcastle (UK) and her team have found out it is actually not only rappers who need an understanding of rhythm in their language, we all do.
While talking, people put together sequences of rhythmic and melodic patterns to convey their intentions. If the rhythm was “wrong” in some way, the message can easily be misunderstood (Imagine Marshall Mathers asking for your attention in this way: “Ma-y-I-ha-ve-you-r-at-ten-tion-plea-se?”). This may be why many rappers tend to carry a strong sense of time, not only when spitting bars with a good flow, but also when plainly speaking.
One of the studies (Grube et al., 2012) showed how closely related the phonological skill you need to speak is to the ability to process short sequences of rhythmic patterns. 238 eleven-year-olds from a school in Newcastle were given standard language & intelligence tests and had their pitch and rhythm perception tested. Specifically, the ability to perceive isochrony violations in short sequences reveals a link between rhythm perception and speech processing, where anisochrony detection is the ability to notice when something is ‘just’ out of time (‘off-beat’). In short, if you are better at detecting whether something is just off-beat, then you will likely be better at processing language and even at producing speech. In a follow-up study (Grube et al. 2014), to test whether this was true for people with atypical development, 28 students with dyslexic traits from the same school underwent the same procedure and the results were not replicated, meaning it was only the case for typically developing children.
In a further study of 24 undergraduates (2013), Grube et al. found that the rhythm perception for longer, more complex ‘roughly regular’ sequences played a role in language processing, specifically in reading. This differed from the 11 year-olds, for whom the perception for shorter rhythmic sequences was more important. In their present work at TU Berlin, Grube and colleagues are tracing the neural time signature of the processing of more complex sequences with a ‘pseudo-rhythmic’ beat similar to that of speech.
“And every single person is a Slim Shady lurking”
If so, where is this rhythm processing taking place?
In preceding studies on these aspects of rhythm perception, Grube and colleagues showed evidence, using techniques varying from transcranial magnetic stimulation (TMS) to functional magnetic resonance imaging (fMRI) (Grube et al., 2010; Teki et al., 2011), that specific brain areas play a differential role in processing different kinds of timing mechanisms. Teki et al. (2011) measured the perception of rhythmic timing in the human brain using fMRI and found what is shown in the picture (in grey yellow and green). When participants focused on the absolute duration of a series of time intervals, the cerebellum and inferior olive (marked yellow in the picture), was activated. However, when participants perceived time intervals compared to a regular beat, the putamen and the neocortex (green), were activated. In most recent work, Grube et al. (in prep.) investigated which brain structures supports rhythm processing and its relationship with speech and language skill during adolescent development. Using structural MRI on 42 participants, their initial results suggest that parts of the cerebellum are specific for rhythm, whilst an area around the left intra-parietal sulcus supports the relationship with language.
“So won’t the real Slim Shady please stand up […]?”
What can impairments tell us about these regions?
The cerebellum is one part of the brain that is involved largely in motor control. In 2010, Grube et al. found that patients with cerebellar degeneration showed a significant deficit in duration-, but not beat-based timing, supporting the existence of functionally distinct aspects of rhythm processing. The basal ganglia, a structure consisting of many nuclei including the putamen, controls our voluntary motor movements and is involved in learning and emotion processes. In 2014, Cope et al. found that patients with basal ganglia disease showed deficiencies in both duration- and beat-based tasks. This finding provides evidence for some functional link, i.e. a differential involvement of both types of perceptual timing (Teki et al., 2012) as opposed to the clear function divide suggested by Teki et al. (2011). Consistent with this, Launay et al. (2014) found that participants with dysrhythmia showed an opposite dissociation; an impairment in beat-, but not duration-based timing. In conclusion, these findings provide evidence for a more complex model of rhythm processing in humans than has been previously proposed.
This research is still very much in its early stages, and a fantastic insight into the way we understand ourselves, our faculties of action and perception and the role for timing in them. Further examination will need to be conducted in order to reveal just how the basal ganglia and cerebellum and cortex interact in rhythm perception and speech production. The finding that a strong sense of rhythm can affect our propensity for language is bound to lead on to many interesting investigations in the future. With this in mind Eminem seems to be right in saying:
“Guess there’s a Slim Shady in all of us […] let’s all stand up.”
Written by: Natalie Kohler, Sarah Charles & Connor Higgins, based on a lecture given by Dr. Manon Grube (Thursday 29th October, 2015)
Eminem (2000). The Real Slim Shady. The Marshall Mathers LP, Aftermath Entertainment.
Cope, T. E., Grube, M., Singh, B., Burn, D. J. & Griffiths, T. D. (2014). The basal ganglia in perceptual timing: Timing performance in Multiple System Atrophy and Huntington’s disease. Neuropsychologia, 52, 73-81.
Grube, M., Cooper, F. E., Chinnery, P. F. & Griffiths, T. D. (2010). Dissociation of duration-based and beat-based auditory timing in cerebellar degeneration. Proceedings of the National Academy of Sciences, 107(25), 11597-11601.
Grube, M., Cooper, F. E. & Griffiths, T. D. (2013). Auditory temporal-regularity processing correlates with language and literacy skill in early adulthood. Cognitive neuroscience, 4(3-4), 225-230.
Grube, M., Kumar, S., Cooper, F. E., Turton, S. & Griffiths, T. D. (2012). Auditory sequence analysis and phonological skill. Proceedings of the Royal Society of London B: Biological Sciences, 279(1746), 4496-4504.
Launay, J., Grube, M., & Stewart, L. (2014). Dysrhythmia: a specific congenital rhythm perception deficit. Frontiers in psychology, 5.
Teki S., Grube M., Griffiths T.D.. (2012) A unified model of time perception accounts for both duration-based and beat-based timing mechanisms. Front Integr Neurosci 5, 90.
Teki, S., Grube, M., Kumar, S. & Griffiths, T. D. (2011). Distinct neural substrates of duration-based and beat-based auditory timing. The Journal of Neuroscience, 31(10), 3805-3812.
Picture 1: http://www.collegedj.net/wp-content/uploads/2011/02/Dr-Dre-Eminem.jpg (viewed: November 16, 2015).
Picture 2: Teki, S., Grube, M., Kumar, S. & Griffiths, T. D. (2011). Distinct neural substrates of duration-based and beat-based auditory timing. The Journal of Neuroscience, 31(10), 3810.