A five-microphone method to measure the reflection coefficients of headsets

In binaural audio, particularly when using headphone for sound reproduction, the reflections from a headset to the ear canal can have a considerable compact on listeners' subjective perception. They may affect the electroacoustic transfer function from the electrical input of headsets to the sound pressure at the eardrum. In order to characterize such effects, it is needed to measure the reflection coefficients from headsets to ears. A widely used measurement method is the transfer function method, which is described in ISO-105340-2. However, the frequency range above 10 kHz may not be accurately measured with only a single pair of measurement sensors. In this paper, a five-microphone method is proposed for measuring the reflection coefficients using an impedance tube with a standard pinna simulator that the headsets coupled. Comparisons are made between the new method and the one microphone technique for the experimental results. It is showed that the measured results agree well and the accuracy of the proposed method can be up to 16 kHz. This method can be expected to have applications in model the acoustic transfer functions of external ears as well as to headphone sound reproduction.