Evaluation of Equalization Methods for Binaural Signals

The most demanding test criterion for the quality of binaural simulations of acoustical environments is whether they can be perceptually distinguished from a real sound field. If the simulation provides natural interacting and sufficient spatial resolution, differences are predominantly perceived in terms of spectral distortions due to a non-perfect equalization of the transfer functions of the recording and reproduction systems (dummy head microphones, head-phones). In order to evaluate different compensation methods, several headphone transfer functions were measured on a dummy head. Based upon these measurements, the performance of different inverse filtering techniques re-implemented from literature was evaluated using auditory measures for spectral differences. Additionally, an ABC/HR listening test was conducted, using two different headphones and two different audio stimuli (pink noise, acoustical guitar). In the listening test, a real loudspeaker was directly compared to a binaural simulation with high spatial resolution, which was compensated using seven different equalization methods.