Bird Speech Perception and Vocal Production: A Comparison with Humans

Abstract

Research into speech perception by nonhuman animals can be crucially informative in assessing whether specific perceptual phenomena in humans have evolved to decode speech, or reflect more general traits. Birds share with humans not only the capacity to use complex vocalizations for communication but also many characteristics of its underlying developmental and mechanistic processes; thus, birds are a particularly interesting group for comparative study. This review first discusses commonalities between birds and humans in perception of speech sounds. Several psychoacoustic studies have shown striking parallels in seemingly speech-specific perceptual phenomena, such as categorical perception of voice-onset-time variation, categorization of consonants that lack phonetic invariance, and compensation for coarticulation. Such findings are often regarded as evidence for the idea that the objects of human speech perception are auditory or acoustic events rather than articulations. Next, I highlight recent research on the production side of avian communication that has revealed the existence of vocal tract filtering and articulation in bird species-specific vocalization, which has traditionally been considered a hallmark of human speech production. Together, findings in birds show that many of characteristics of human speech perception are not uniquely human but also that a comparative approach to the question of what are the objects of perception--articulatory or auditory events--requires careful consideration of species-specific vocal production mechanisms.

Vocal tract articulation revisited: the case of the monk parakeet

“…The fact that songbirds and humans exhibit many parallels in vocal learning and perception (e.g. Doupe and Kuhl, 1999;Ohms et al, 2010a;Ohms et al, 2011;Beckers, 2011) has established songbirds as an excellent model system in which to study the underlying mechanisms in both birds and humans (Bolhuis et al, 2010). Also, cognitive mechanisms related to syntax detection might be comparable in humans and songbirds, although the results are controversial (Gentner et al, 2006;van Heijningen et al, 2009).…”

Defects in Ultrasonic Vocalization of Cadherin-6 Knockout Mice

“…Although only humans are able to use language, components of language are seen in some nonhuman animals [1], [2]. Many studies investigating the neural basis of human language have therefore focused on the vocal communication of animals [3]–[12]. Songbirds have been used as animal models in studies investigating the brain mechanisms of complex vocalization including human language because they sing complex songs with sequential roles as human speech.…”

Evolution of Vocal Diversity through Morphological Adaptation without Vocal Learning or Complex Neural Control

“…Instead of the main sound source, the tracheal membranes constitute a morphological specialization, which, through interaction with bronchial labia, contributes to different acoustic features such as: spectral complexity, amplitude modulation, enhanced sound amplitude. In contrast, these same features arise in oscines from neuromuscular control of two labial sources [15–17]. These findings are supported by a modeling approach and provide a clear example for how a morphological adaptation of the tracheophone vocal organ can generate specific, complex sound features.…”