### ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

## 2pPP46. Infinite-Impulse-Response filter models of the head-related
transfer function.

**Abhijit Kulkarni
**
H. Steven Colburn

**
**
*Dept. of Biomed. Eng., Boston Univ., 44 Cummington St., Boston, MA 02215
*

*
*
Directional-transfer-functions (DTFs) derived from head-related transfer
functions (HRTFs) measured from human subjects in an anechoic environment were
modeled using auto-regressive (AR) and auto-regressive moving-average (ARMA)
modeling techniques. The HRTFs, which were provided by Dr. Fred Wightman
(Wightman and Kistler, 1989), were decomposed into a
directional-transfer-function (DTF) and a mean-function (computed as the mean
of all measured HRTFs for that subject). Model reconstructions of the HRTFs was
done under the assumption that HRTFs are minimum-phase functions. The AR
estimator which is derived from the theory of linear prediction, corresponds to
an all-pole model of the DTF. The ARMA model extends the all-pole model to a
pole-zero model and is derived by posing a weighted-least-squares formulation
of the modified-least-squares problem proposed by Kalman (1958). The validity
of each model was assessed psychophysically using a 4I, 2AFC paradigm. Using a
80-ms white noise stimulus and testing a different position on each trial, for
a 25-pole all-pole model and a 6-pole 6-zero pole-zero model, subjects
performed close to chance for most of the 13 representative positions tested.
[Work supported by NIDCD (Grant DC00100).]