Application of the source-filter theory of voice production to the vocal signals of a non-passerine bird: Acoustic coding in Herring gulls

The aim of this project is to study the vocal communication system in one of the most common seabirds, the Herring gull. This project will take advantage of the fact that the vocalisations of many non-passerine birds species, including herring gulls, are often characterised by a complex spectral structure, which is composed of a fundamental frequency, harmonics and resonance frequencies, and is very similar to that of human speech and other mammal vocal signals. This similarity, a consequence of analogous modes of production, enables us to apply sophisticated sound analysis tools initially developed for studies of human speech and based on the "source-filter" theory of voice production.

Integrating investigations at several levels, ranging from the functional anatomy of the signaller to the perceptual abilities of the receiver, we plan to: 
1) provide the first detailed description of the acoustic structure of herring gull calls; 

2) investigate the relationship between the vocal apparatus dimensions and gender, size, age and condition, in order to predict how the structure of calls will reflect these attributes; 

3) test these predictions by analysing recordings from birds of known attributes; 

4) assess whether gulls perceive and use this information during territorial contests, using playbacks of calls re-synthesized using a sophisticated technique called PSOLA resynthesis, which enables to generate highly realistic stimuli in which one parameter (the pitch, the duration, or the resonances) is varied while the others are kept constant. This would, to our knowledge, be the first study to apply PSOLA to bird vocalisations. 

Investigators:
 
Loic Hardouin (Postdoc)
David Reby (Supervisor)



Vocal communication of male quality in Scops Owls

See press release, and a report on Fox News.

http://www.sussex.ac.uk/press_office/media/media607.shtmlhttp://www.foxnews.com/story/0,2933,269288,00.htmlshapeimage_2_link_0shapeimage_2_link_1
 
School of Psychology