Construction of a HATS and its HRTF measurement for 3-D sound

Abstract

Based on the anthropometric data on the head and torso dimensions in Korean male adults, a head and torso simulator (HATS) was constructed. Data, which have no counterparts in the Korean standards, were used with ANSI S3.36-1985. Measuring microphones can be positioned at the eardrum or at the ear canal entrance according to measuring purposes. Head related transfer functions (HRTFs) for the HATS, i.e., binaural impulse responses, were measured at 710 points on a spherical surface of radius 1.55 m using a burst maximum length sequence (MLS) signal of 65 535 samples in an anechoic chamber. The measurement system consists of one part to generate the MLS signal and to drive a Boss 101A loudspeaker and another part to record the output signal of a microphone in the HATS and consequently to measure the impulse response. Also measured were the impulse responses of the driving loudspeaker and some headphones for 3-D sound reproduction in order to get the exact HRTF of the HATS-alone. The impulse-version HRTFs at the sampling frequency of 44.1 kHz, which have filter lengths of 512 points with minimum phase characteristics and can be used for 3-D sound, were finally obtained through a postprocessing procedure.