Music and Language: Relations and Disconnections
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Handbook of Clinical Neurology, Vol. 129 (3rd series) The Human Auditory System G.G. Celesia and G. Hickok, Editors © 2015 Elsevier B.V. All rights reserved Chapter 12 Music and language: relations and disconnections NINA KRAUS1,2,3,4*,† AND JESSICA SLATER1,2 1Auditory Neuroscience Laboratory, Northwestern University, Evanston, IL, USA 2Department of Communication Sciences, Northwestern University, Evanston, IL, USA 3Department of Neurobiology and Physiology, Northwestern University, Evanston, IL, USA 4Department of Otolaryngology, Northwestern University, Evanston, IL, USA INTRODUCTION some of the very same aspects of sound encoding that are deficient in impaired populations and discuss the Above all, music and language are forms of human com- implications for clinical and social contexts. munication. Since sensory function is ultimately shaped by what is biologically important to the organism, the human urge to communicate has been a powerful driving MUSIC AND LANGUAGE: STRUCTURAL force in both the evolution of auditory function and the AND FUNCTIONAL ORIGINS ways in which it can be changed by experience within an individual lifetime. The ability to extract meaning from Structure rooted in sound sound requires that all aspects of the auditory system Both music and language are complex communication work together in concert: by considering human auditory systems, in which basic components are combined into function in the context of communication, we hope to higher-order structures in accordance with rules. emphasize the highly interactive nature of the auditory Whether music was an evolutionary precursor to lan- system as well as the depth of its integration with other guage (Mithen, 2005) or merely a byproduct of cognitive sensory and cognitive systems. Through consideration faculties that developed to support language (Pinker, of relations and dissociations between music and lan- 1999), music is pervasive across human cultures and guage we will explore key themes in auditory function, throughout history, with evidence of prehistoric bone learning and plasticity. and ivory flutes dating back over 42,000 years First we will look to the origins of music and lan- (Higham et al., 2012). The capacity of music to convey guage: we shall not attempt to resolve the ongoing debate emotion is driven not only by cultural conventions but regarding their evolutionary status, but we will consider by the underlying psychophysical properties of sound what their structural characteristics and functional ori- and cochlear mechanics (Balkwill and Thompson, gins reveal about the human relationship with sound. 1999; Tramo et al., 2001; Gomez and Danuser, 2007). Then we will focus on the role of temporal structure For example, the perception of consonance and disso- in music and language, and how temporal patterns pro- nance arises at least in part from the different vibration vide a framework for information processing in the patterns generated by combinations of frequencies and brain. Next we will consider how music and language their harmonics on the basilar membrane, where conso- are learned, emphasizing interactions between the audi- nant intervals comprise simple frequency ratios and gen- tory system, cognition, and emotion and reward centers erate less interference than dissonant intervals (Von in the brain. The final section of this chapter will focus on Helmholtz, 1912). Consonant intervals are typically con- the biology of sound processing and how experience with sidered to be pleasing to the ear (Trainor, 2008), which music and language influences underlying neural func- may reflect a relationship between ease of perceptual tion. We will show that auditory expertise strengthens processing and positive emotional state (Reber et al., *Correspondence to: Nina Kraus, Ph.D., Northwestern University, 2240 Campus Drive, Evanston, IL 60208, USA. Tel: +1-847-491- 3181, Fax: +1-847-491-2523, E-mail: [email protected] †Auditory neuroscience lab website: www.brainvolts.northwestern.edu 208 N. KRAUS AND J. SLATER 1998, 2004). Children’s innate receptivity to music from background (Parbery-Clark et al., 2009b; Kraus and a very young age, including their ability to perceive con- Chandrasekaran, 2010; Anderson et al., 2013). Taken sonance and dissonance (Trainor and Heinmiller, 1998; together, these outcomes emphasize that the ability to Zentner and Kagan, 1998; Trehub, 2003), reinforces make sense of sound in a communication context relies the idea that musical structure is rooted in fundamental heavily upon integration between the auditory system characteristics of sound and sensory perception. and other cognitive and sensory systems. We will provide An important distinction between music and lan- further discussion of how these relationships are medi- guage is in their differing degrees of semantic specific- ated by experience with music and language in the final ity. While language can be used to convey precise section of this chapter. semantic content between individuals, precision can also lead to disagreement; music lacks semantic specificity TEMPORAL PROCESSING IN MUSIC but plays an important role in promoting social bonding AND LANGUAGE (Cross, 1999; Trehub, 2003), as demonstrated experi- mentally by an increase in cooperative behavior in young The auditory system plays a unique role as the temporal children following joint music making (Kirschner and processing “expert” in the nervous system, with micro- Tomasello, 2010). In this sense, language enables articu- second precision required for the localization of sounds lation of what is within us, whereas music strengthens (Mauk and Buonomano, 2004). The ability to lock on to what is shared between us. temporal patterns is a fundamental aspect of auditory processing, and is especially important for the percep- tion of communication sounds: meaningful information Communication in context unfolds simultaneously over multiple timescales in both While we are largely focused on music and language as speech and music, from overarching rhythms and stress forms of auditory communication, it is important to patterns, to the fine-grained timing differences which acknowledge that the auditory system does not function differentiate consonants and characterize the distinctive in isolation, especially within the context of communica- timbre of a voice or musical instrument. tion. Other sensory modalities, such as vision, help the The timing precision of the auditory system is also brain to construct a percept of sound object (Schutz important for sensorimotor coordination, with a study and Lipscomb, 2007; Musacchia et al., 2008) and can of 16 normal adults showing that synchronization of fin- influence speech perception. This is demonstrated by ger tapping to an auditory stimulus is more accurate than the McGurk effect, in which a video presenting repeated to a visual stimulus (Repp and Penel, 2002), and a study utterances of the syllable [ba] dubbed on to the lip move- from our laboratory with 124 typically developing ado- ments for [ga] result in normal-hearing adults perceiving lescents showing that the ability to synchronize with a a hybrid percept, the syllable [da] (McGurk and beat tracks with more consistent subcortical neural tim- MacDonald, 1976). In the case of music and language, ing in the auditory system in response to speech sounds this cross-modal integration is important in helping to (Tierney and Kraus, 2013a). determine the communicative intent which produced a The integration between auditory and motor systems sound, and thereby determining its meaning, thus: is especially strong in vocal learning species, with “Speech is processed both as a sound and as an action” co-activation of comparable motor and auditory brain (Scott and Johnsrude, 2003). Similarly, it has been shown regions in both humans and songbirds during vocal that the perception of musical performances can be sig- learning tasks (Brown et al., 2004). Rhythm perception nificantly influenced by non-auditory cues, such as body involves activation of motor regions of the brain movements (Tsay, 2013). (Zatorre et al., 2007; Chen et al., 2008), and it has been Music and language are likely to have evolved in con- proposed that the ability to synchronize to a beat may junction with important shifts in the emergence of rely upon the same auditory-motor neural infrastructure human cognition, and while the exact sequences and that evolved to support vocal learning (Patel, 2006; Patel interdependence of these evolutionary trajectories are et al., 2008, 2009; Patel and Iversen, 2014). This ability debated (Cross, 1999; Mithen, 2005; Fitch, 2006), it is has been observed in humans and other vocal learning clear that processing of music and language relies upon species but is otherwise very rare in non-human animals, cognitive capacities, such as working memory. There is however, individual cases of beat-keeping abilities in evidence that expertise such as musical training is asso- non-vocal-learning species such as the sea lion (Cook ciated with greater auditory working-memory capacity et al., 2013) leave this a matter of continuing research. across the lifespan (Bugos et al., 2007; Kraus et al., The motor system is not only involved in the produc- 2012), which also relates to better performance on every- tion of linguistic and musical sounds (Zatorre et al., day listening tasks such as perceiving speech in a noisy 2007; Nasir and Ostry, 2009); motor areas are also MUSIC AND LANGUAGE: RELATIONS AND DISCONNECTIONS 209 activated