On the discriminability of virtual and real sound sources

A method for direct comparison between virtual and real sound sources has been developed in which listeners are presented with real sources while wearing small headphones over which virtual sources may also be presented. Adequacy of this method is assessed both acoustically and psychophysically by comparing virtual free-field stimulation to actual free-field stimulation produced by loudspeakers in an anechoic chamber. The effects of windowing the impulse response of the correction filter used for virtual synthesis are also examined. Using this method, it is concluded that when no windowing is applied to the correction filter impulse response (20.48 ms in duration at a 100 kHz sampling rate), stimulation resulting from virtual synthesis is indiscriminable from real sound source stimulation. As window length is decreased, successive increases in discriminability are observed, however. These psychophysical results are consistent with acoustic validation measures.