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

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 vocal pitch production, this ability may still be underdeveloped compared to 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). While participants who sung more precisely also whistled more precisely, sung imitations were less precise than whistled imitations. Furthermore, sung notes were systematically biased towards each individual’s habitual pitch, which may act to conserve muscular effort. 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.

语音模仿（vocal imitation）是人类交流的标志性特征，亦是人类习得言语与歌唱能力的核心基础。即便如此，普通人群中语音模仿能力欠佳的情况竟颇为常见，即便专业歌唱者也无法企及乐器的演奏精度。尽管人类已演化出对调控语音音高产生的喉肌（laryngeal muscles）更强的操控能力，但相较于对构音肌（articulatory muscles，如舌与唇）的控制而言，这一能力仍显不足——对构音肌的随意控制（volitional control）在灵长类演化历程中出现得更早。人类受试者通过两种方式模仿简单旋律：一是歌唱（即通过喉肌生成音高），二是吹哨（即通过唇与舌生成音高）。歌唱精度更高的受试者，其吹哨精度通常也更高，但歌唱式模仿的精度仍低于吹哨式模仿。此外，歌唱出的音符会系统性地偏向每个受试者的习惯性音高，这一现象或有助于节省肌肉发力。调控发声的喉肌，其操控精度低于参与吹哨的口腔肌肉。这种精度不足或许源于人类演化出随意喉肌运动控制的时间相对较晚——该调控系统的优化程度仅足以支撑言语中语音音高的粗略调制。