Vocal Learning and Auditory-Vocal Feedback

Abstract

Vocal learning is usually studied in songbirds and humans, species that can form auditory templates by listening to acoustic models and then learn to vocalize to match the template. Most other species are thought to develop vocalizations without auditory feedback. However, auditory input influences the acoustic structure of vocalizations in a broad distribution of birds and mammals. Vocalizations are defined here as sounds generated by forcing air past vibrating membranes. A vocal motor program may generate vocalizations such as crying or laughter, but auditory feedback may be required for matching precise acoustic features of vocalizations. This chapter discriminates limited vocal learning, which uses auditory input to fine-tune acoustic features of an inherited auditory template, from complex vocal learning, in which novel sounds are learned by matching a learned auditory template. Two or three songbird taxa and four or five mammalian taxa are known for complex vocal learning. A broader range of mammals converge in the acoustic structure of vocalizations when in socially interacting groups, which qualifies as limited vocal learning. All birds and mammals tested use auditory-vocal feedback to adjust their vocalizations to compensate for the effects of noise, and many species modulate their signals as the costs and benefits of communicating vary. This chapter asks whether some auditory-vocal feedback may have provided neural substrates for the evolution of vocal learning. Progress will require more precise definitions of different forms of vocal learning, broad comparative review of their presence and absence, and behavioral and neurobiological investigations into the mechanisms underlying the skills.

Cues to individual identity in songs of songbirds: testing general song characteristics in Chiffchaffs Phylloscopus collybita

“…Tyack 2016) and, therefore, represent good study models for identity signalling. Despite the fact that vocalizations of non-songbirds could be more plastic than previously thought (e.g.…”

Sequence and hierarchy in vocal rhythms and phonology

“…Because the data concerning vocal learning have been frequently reviewed recently, I will discuss only the broad conclusions and not their detailed empirical basis here; for details see Refs. , and , and a recent journal issue that provides concise overviews of complex vocal learning in all of the currently known clades . The first step in discussing vocal learning is to adopt a clear terminology, because there are many types of vocal learning, with very different phylogenetic distributions.…”

“…However, as pointed out more recently by Tyack, even this strict definition allows many distinct types of modification. For example, the Lombard effect is the phenomenon whereby vocalizers increase the intensity of calling in the presence of noise, and is ubiquitous among mammals and documented in both frogs and grasshoppers . If this online intensity change occurs in response to conspecific vocalizations, strictly speaking, it constitutes “vocal production learning” according to the above definition.…”

“…They use this term to denote that "vocalizations are modified in form as a result of experience with those of other individuals." However, as pointed out more recently by Tyack, 46 even this strict definition allows many distinct types of modification. For example, the Lombard effect is the phenomenon whereby vocalizers increase the intensity of calling in the presence of noise, and is ubiquitous among mammals and documented in both frogs and grasshoppers.…”

Untitled

“…57 Vocalizations that develop from juvenile precursors into adult ones, may follow two non 58 mutually exclusive developmental pathways: vocal learning and vocal tract maturation (Janik & 59 Slater 1997). Development of vocalizations by vocal learning implies the ability of juveniles to 60 modify their vocalizations based on the copying of sounds from an external auditory input, 61 typically from conspecifics (Tyack 2016). Juveniles of vocal learners can modify the acoustic 62 features of their vocalizations and also incorporate new vocalizations to their repertoire as a 63 result of the influence of social interactions (Janik & Slater 1997).…”