Effects of the Types of Headphones and Sound Sources on Spatial Audio Quality

Acoustic characteristics of sound fields reproduced by headphones are a major concern to evaluate spatial audio quality. Several specifications exist for acoustic attributes, including frequency response, impedance, and sensitivity. While prior research has illuminated these acoustic features, it falls short in evaluating the spatial audio quality produced by headphones. Such studies don't sufficiently detail the impact of headphones and sound sources. In this study, we carried out psychological evaluations and acoustical measurements of sound fields reproduced by headphones to identify the acoustic elements that account for the spatial audio quality rendered by the headphones. Three types of sound excerpts were played with seven types of headphones, and the psychological evaluations were carried out by 30 participants. Envelopment and apparent source width were evaluated as psychological evaluations. From the binaural impulse response, we determined the center time (Ts), the maximum value (IACC) of the interaural cross-correlation function (IACF), and the IACC width (W
IACC
). We derived the IACF and auto-correlation function (ACF) parameters from the recorded sound sources. The traits of both the headphones and the sound source influenced the psychological assessments. The variation in spatial audio quality across headphones and sound sources can be attributed to the peak value of the initial maximum amplitude of the ACF, Ts, and W
IACC
.