Poor neuro-motor tuning of the human larynx: a comparison of sung and whistled pitch imitation.

Michel Belyk,Sonja A Kotz,Joseph F Johnson

doi:10.1098/rsos.171544

Abstract

Vocal imitation is a hallmark of human communication that underlies the capacity to learn to speak and sing. Even so, poor vocal imitation abilities are surprisingly common in the general population and even expert vocalists cannot match the precision of a musical instrument. Although humans have evolved a greater degree of control over the laryngeal muscles that govern voice production, this ability may be underdeveloped compared with control over the articulatory muscles, such as the tongue and lips, volitional control of which emerged earlier in primate evolution. Human participants imitated simple melodies by either singing (i.e. producing pitch with the larynx) or whistling (i.e. producing pitch with the lips and tongue). Sung notes were systematically biased towards each individual's habitual pitch, which we hypothesize may act to conserve muscular effort. Furthermore, while participants who sung more precisely also whistled more precisely, sung imitations were less precise than whistled imitations. The laryngeal muscles that control voice production are under less precise control than the oral muscles that are involved in whistling. This imprecision may be due to the relatively recent evolution of volitional laryngeal-motor control in humans, which may be tuned just well enough for the coarse modulation of vocal-pitch in speech.

Highlights

Vocal imitation is a hallmark of human communication that underlies the capacity to learn to speak and sing
The continuous range of scores observed in this sample and reported by Peretz et al lead us to retain the data from all participants but include Montreal Battery of Amusia Evaluation (MBEA) scores as a continuous predictor in subsequent analyses
We report the results of a study on pitch imitation in singing with the laryngeal sound source compared with whistling with an oral sound source

Summary

Introduction

Vocal imitation is a hallmark of human communication that underlies the capacity to learn to speak and sing Whereas the ability to flexibly produce calls from an existing repertoire (vocal usage learning) is relatively common, the ability to add new vocalizations to an existing repertoire (vocal production learning) is rare in mammals [2,3]. How the hominid vocal phenotype evolved from vocal usage to vocal production learning remains a matter of speculation. Several plausible hypotheses have been advanced to suggest, for example, that emotional expression may have provided a scaffold for the evolution of speech and song [16], or that the exaggeration of social dominance cues provided selective pressure for more versatile voices [17], which may have been exploited by early hominins for the purpose of communication [18]

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Conclusion