Inverse filtering of headphones for binaural sound reproduction
Pauli Minnaar, Henrik Møller · The Journal of the Acoustical Society of America · 1998
Binaural recordings can be made at a blocked ear canal entrance and can be conveniently played back over headphones. The total transmission is then characterized by a transfer function that includes the responses of the headphone and the microphone as well as the transmission between them. The transfer function can be broken up into a minimum phase and an excess phase component, of which the latter can again be broken up into an all-pass and a linear phase component. In order to make the binaural system acoustically transparent, an equalization filter must be designed as the inverse of the total transfer function. The suitability of various filters for inverting each of the transfer function components is evaluated using data from real ear measurements. The robustness of the equalization is discussed with respect to slight changes in headphone and microphone placement. For the investigation 2892 measurements were made on a range of people wearing various types of headphones and wearing different samples of the same type of headphone.