Scholarly work: Rhythm, language and learning and Have you heard of the auditory brainstem? by Marion Long

A scholarly blog from Dr. Marion Long. Thank you Marion.

Rhythm, language and learning

2 October 2015

How do tunes and rhymes find their way into our heads? Although repetition seems to be important for any type of learning, patterns of words and tunes seem to have an almost magnetic quality in the way that they spontaneously stick in the mind. This type of learning is extremely powerful. It’s known as implicit learning as it appears to require no effort at all.

Scholars have identified the importance of implicit learning for infant language development. In fact, they have revealed that infants are naturally sensitive to the distribution and frequency of patterns. The power of this, so-called statistical learning was clearly demonstrated when infants responded to rhythmic patterns in language, even when the natural intonation or prosodic features in speech had been removed (Saffran et al., 1996).

It seems that implicit language learning is a natural response to regular occurrences such as rhythmic patterns and sequences in the sounds of language. Infants hear these in their everyday exposure to language and also by producing patterns through babbling. According to Vihman (2015), this is why the development of language is to a degree, individual for each infant. A virtuous cycle soon develops once infants have realised that things around them have names and begin to learn words more deliberately and explicitly, storing phonological representations of words as symbolic, semantic associations. Language learning continues as infants identify probabilistic patterns within words, again through implicit learning and this leads to sensitivity and production of grammatical structures. Isn’t the strength, power and universality of these processes absolutely remarkable?

Saffran, J. R., Richard N. A., and Newport, E. L. (1996). “Statistical learning by 8-month-old infants.” Science 274.5294, 1926-1928.

Have you heard about the auditory brainstem?

1 November 2015

Our ears are open all the time. Even sleeping newborn infants subconsciously respond to the sounds around them, indicating that from birth (1), humans are constantly exposed to their auditory environment.

In their review of the research evidence, Kraus & Chandrasekaran, (2) underlined the importance of the initial, subconscious (subcortical) stage of auditory processing. Before sound reaches our attention, the auditory brainstem responds to incoming information from our ears, integrating the spatial, rhythmical and acoustical features of sounds.

These features include frequency (high and low pitches), the timbre of the sound (for example, differentiating between human voices) and rhythmic features (such as the regularity or predictability of sounds). The auditory brainstem is extremely sensitive to very subtle differences in sound waves, such as individual phonemes in language and plays a critical role in early identification of sounds and their patterns in particular. Over time, the auditory brainstem produces an idiosyncratic response to sound that is unique to each individual.

Thus, the auditory brainstem response reflects the current state of the nervous system – the state at that time formed by an individual’s life experience with sound (ibid, 2010, pp. 601).

More recently, researchers have found that the auditory brainstem seems to respond with greatest clarity to the sounds with which the individual is most familiar. Having listened to brainstem responses of musicians, they found that for example, pianists’ brainstem responses to the sounds produced by a piano were unusually sharply defined when compared to those of non-pianists. Brainstem responses also appeared to receive feedback information from cortical areas of the brain (3).

Further developing the line of enquiry, scholars (4) proposed that the availability of cortical feedback (from the cognitive processing of sound) allowed the brainstem response to become increasingly specific over time. For instance, musical expertise that has accumulated over a lifetime leads to extremely fine-grained auditory brainstem responses among professional musicians, not only to musical sounds, but also both to phonemes and the pitch contours of language (5). Once the brainstem has adapted to cortical feedback, it appears to retain its enhanced structures as confirmed by a recent study of speakers of Mandarin and amateur musicians (6).

Overall these studies show that an overlap exists between early stage auditory processing of spoken language and musical experiences. Cognitive feedback informs development of these structures and expertise in music appears to enhance the auditory brainstem response to language.

1. Nameth, R., Haden, G., Miklos, T. & Winkler, I (2015) Processing of horizontal sound localization cues in newborn infants, Ear and Hearing, 36 (5), pp. 550-556

2. Kraus, N and Chandrasekaran, B. (2010) Music training for the development of auditory skills, Nature Neuroscience, 11, pp. 599-605

3. Strait, D.L. Chan, K., Ashley, R., & Kraus, N (2010) Specialisation among the specialised: Auditory brainstem function is tuned to timbre, Cortex, 48, pp. 360-362

4. Skoe, E., Krizman, J., Spitzer, E., & Kraus, N. (2014) Prior experiences biases subcortical sensitivity to sound patterns, Journal of Cognitive Neuroscience, 27 (1), pp.124-140

5. Musacchia, G., Sams, M., Skoe, E. & Kraus, N. (2007) Musicians have enhanced subcortical auditory and audiovisual processing of speech and music. Proc. Natl Acad. Sci. USA 104.

6. Bidelman, G.M., Gandour, J.T., Krishnan, A., (2011). Cross-domain effects of music and language experience on the representation of pitch in the human auditory brainstem. J. Cogn. Neurosci. 23, 425–434.

– See more at: http://rhythmforreading.com/a/blog#sthash.cbw1SbNd.dpuf

Vihman, M. (2015) Handbook of Language Emergence. MacWhinney, B. & O’Grady, W. (eds.). Malden, MA: Wiley-Blackwell, p. 437-457

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