Room-induced cues for the perception of virtual auditory distance with stimuli equalized in level

Auditory distance was judged by listeners wearing headphones for a frontal source in a virtual room. Nonindividualized head-related transfer functions were used to simulate distances ranging from 0.5 to 10 m and the broadband level was held constant. A single sample of pink noise was used in experiment 1 and a single speech sentence in experiment 2. In experiment 1, some noise waveforms were "cut" to eliminate onsets and offsets, so that the reverberant tails on transients were not accessible to the listeners in these stimuli. Finally, in both experiments, both dichotic (normal binaural) and diotic (interaurally identical) waveforms were used, intermixing trials with dichotic, left-ear diotic, and right-ear diotic stimuli. Results showed differences in distance estimates that were consistent with the use of room coloration as a monaural spectral cue. The cut noises were perceived as closer than those with normal onsets and offsets, suggesting that the reverberant tail on transients could constitute a complementary monaural temporal cue. Dichotic stimuli were perceived as closer than diotic stimuli (only at the longest simulated distance for the noise), consistent with binaural hearing making the signals sound less reverberant.