My main research focuses on investigating the origin, structure and function of vocal signals in vertebrates, including humans.

I use an integrated, multilevel approach to address key questions on the function and evolution of vocal communication. I conduct and supervise observational and experimental studies on both captive and free-ranging species, such as deer, owls, herring gulls and domestic dogs. More recently I have started investigating the function of human vocalisations, as well as the expression and perception of gender and related attributes in the human voice.

Using a combination of anatomical investigations, acoustic analyses and playback experiments, I have made the following contributions to the fields of animal communication and cognition:

  • The discovery that male deer have a descended larynx, an anatomical innovation previously believed to be uniquely human and a prerequisite for the emergence of human speech (Fitch & Reby 2001)
  • The demonstration that vocal tract resonances, the basis of phonetic diversity in human speech, play a key role in non-human mammal vocal communication as honest indicators of size in mammal vocal signals (Reby & McComb, 2003; Reby et al. 2005)
  • The demonstration that anatomical constraints play an essential role in establishing honesty in signalling, and thereby influence the evolution of animal signals (Reby & McComb, 2003).
  • The experimental demonstration that both male and female red deer use size-related variation in vocal tract resonances in mate competition and mate choice contexts (Reby et al. 2005, Charlton et al. 2007), and that dogs also use vocal tract resonances to assess body size in conspecifics (Taylor et al. 2010 & 2011).
  • The demonstration that non-human mammals, like humans, can have individual “voices”, i.e. voice cues to identity that are present across the vocal repertoire rather than specific to individual call types (Reby et al. 2006)
  • The demonstration that mammals, like humans, are capable of auditory and visual cross-modal recognition of their conspecifics (Proops et al. 2009).
  • The discovery that male koalas have eloved an additional pair of vocal folds, located at the entrance of their nasal cavity, which allows them produce extraordinarily low-pitched mating calls (Charlton et al. 2013).
  • The demonstration that fundamental and formant frequencies mediate the expression and perception of gender attributes in children's and adults' voices (Cartei & Reby 2013, Cartei et al. 2012, 2013, 2014).
  • The demonstration that dogs express equivalent orientation biases to humans in response to different communicative characteristics of human voices (Ratcliffe & Reby 2014), indicating that dogs process human speech in a way that parallels humans'.

By identifying animal precursors of key features of human speech and cognitive abilities, these studies have implications that provide essential background for studies of the origins of speech production and speech perception abilities in humans.

For details an up-to-date list of publications, please visit my ResearchGate Profile.