Welcome to the Auditory Neuroscience Laboratory. The
laboratory
is located in the Department of
Physiology, at the
University of
Sydney but involves researchers drawn from a number of Departments
and Faculties across the University and other institutions.
Members of the lab
-
Associate Professor Simon
Carlile, Physiology, Pro-Vice Chancellor (Information Technology)
-
Dr Andre Van Schaik - Senior Lecturer (School of Electrical and Information
Engineering), Honorary Associate, Physiology.
-
Dr Craig Jin - Garnette Passe and Rodney Williams Foundation Fellow
-
Dr Oliver Behrend - Visiting Scholar Akademie Der Natur Forscher Leopoldina
-
Johahn Leung - PhD Student
-
Virgina Best - PhD Student
-
Ruben Kurilowich - PhD Student
-
Anandhi Anandan - Part time Research Assistant
Current Research interests
Associate Professor Simon Carlile directs a multi-disciplinary research
group aimed at understanding the mechanisms by which the auditory system
encodes sound direction and the perception of sound localisation. Sounds
are generated in the free field and in so-called virtual auditory space
(VAS). Research projects involve acoustics, neural coding, behavioural/psychophysical
studies, computer simulations and digital signal processing. A major facility
of the laboratory is a large anechoic chamber, equipped with one of the
world's most advanced moving speaker assemblies. It is based on a high
speed robotic arm rotating about a central axis, and designed to deliver
sound signals positioned precisely in three-dimensional space.
The principal research areas are:
The laboratory
is equipped to use both free field and virtual
space techniques to examine these issues.
Applied research
If a sound is filtered in a way which resembles the filtering of the outer
ear before being presented through head phones, the illusion of sounds
in the external word can be generated. Such an impression is referred to
as virtual auditory space (VAS). The filtering characteristics of
the outer ears can be measure using careful bioacoustic measurement techniques
and are referred to as the head
related transfer functions (HRTFs).
The main aim of the applied research in this laboratory is to improve
the fidelity, the generalizability and the efficiency of the generation
of VAS.
There are two main problems that we are addressing.
-
Because everybody's ears are shaped slightly differently, the fidelity
of a VAS simulation which is based on a standard library of HRTFs varies
between listeners. Currently, the only way around this problem is to record
the HRTFs for each operator of a virtual display.
-
If a simple impulse response description of the HRTF is used this results
in a considerable computational load when attempting to simulate complex
auditory environments with multiple sources and reflections which are coupled
with self induced and sound source motion.
Therefore, objectives of the applied research program are:
-
To determine the bio-acoustic basis for the variation in the fidelity of
the auditory perception. This involves measurements of the acoustic and
physical characteristics of the ears of real human listeners combined with
acoustical and mathematical modeling of the auditory periphery using a
specially constructed mannequin with model ears.
-
To increase computational efficiency by identifying and eliminating perceptually
irrelevant information in VAS stimuli. This work involves the investigations
of a number of statistical descriptions of the HRTF (e.g. PCA,/KLT) and
the impact of these manipulations on the perceptual fidelity of the resulting
VAS.
-
To develop methods to enhance perceptually important features in the signals
so as to "tune" a HRTF library for individual operators of VAS displays.
-
To examine the processes by which an operator adapts to the VAS display.
In addition we offer a measurement
service to record the human HRTFs and also a large library
of
HRTFs available for distribution.