ABSTRACT: 3D sound is an important component of many contemporary human computer interfaces. Traditional surround sound techniques such as the use of multiple speakers present some limitations in creating an immersive 3D environment. These techniques are particularly challenged in emulating sound locations outside the horizontal plane. Binaural sounds delivered through headphones can be rendered in any desired location using HRTFs and they are more realistic than traditional stereophonic sounds.
One of the commonly encountered problems in sounds generated using HRTFs is the "Cone of Confusion". Sounds coming from the front (azimuth 0░) are perceived to be coming from the back (azimuth 180░) and vice versa, due to the symmetry of the human head. Observations from 20 subjects suggested that HRTFs from subjects with particularly protruding ears show accentuated spectral differences between symmetric locations. These HRTFs were helpful in resolving the cone of confusion when used by subjects with average or small pinna protrusions. This paper describes how to synthesize attenuation/amplification profiles based on those seen in HRTFs from protruding ears and how they are applied to modify the HRTFs of several subjects. Listening tests showed that the HRTFs so modified yielded enhanced front-back differentiation, with respect to the original HRTFs of the test subjects.