Evaluation of the Respective Effects of Microphone Type and Dummy Head Type on Measured Head-Related Transfer Functions

A dummy head is a tool used to generate binaural recordings, i.e. recordings when listened to through headphones that allow for the listener to hear from the dummy's perspective. A dummy head typically includes pinnae and ear canals in which microphones are placed. The global shape of a dummy head replicates an average-sized human head, and variations around this average will depend on the manufacturer (pinnae of different size, presence of a nose or a mouth). This paper describes measurements conducted on two dummy heads in order to evaluate and rank the respective influence of microphone type and dummy head shape on spatialization cues. Four possible cross configurations are tested, that is head 1 or 2 with microphones pair 1 or 2. For each configuration, head-related transfer functions are measured in an anechoic room for various azimuth and elevation angles. The results obtained show that the effect of the dummy head shape is larger than the effect of the microphone type on measured head-related transfer functions. A practical implication of this result is found when microphones have to be replaced on a given dummy head.