Directional Dependence of Spectrum and Correlation Functions of the Signals Received at the Ears

Broadband noise is presented to an artificial human head with built-in microphones as ears. For directions of sound incidence in the median plane the loudness densities of the signals received at the ears of this dummy-head are measured. By this the directional dependence of masking for the median plane can be explained.

Furthermore the auto- and crosscorrelation functions of the ear signals are measured for real sound sources and for phantom sources of numerous spatial directions. The interaural time difference is determined from the crosscorrelation functions. The limiting frequencies of the received noise signals are determined from the autocorrelation functions. The influence of these limiting frequencies on the apparent elevation angles of sound sources in the median-plane is investigated. Directional hearing tests are carried out for this with real sound sources as well as with phantom sources.