Perceiving auditory distance using level and direct-to-reverberant ratio cues

The study investigated how level and reverberation cues contribute to distance discrimination, and how accuracy is affected by reverberation cue strength. Sentence pairs were presented at distances between 1 and 8 m in a virtual room simulated using an image-source model and two reverberation settings (lower and higher). Listeners performed discrimination judgments in three conditions: level cue only (Level-Only), reverberation only (Equalized), and both cues available (Normal). Percentage correct judgment of which sentence was closer was measured. Optimal distance discrimination was obtained in the Normal condition. Perception of the difference in distance between sentences had a lower threshold (i.e., performance was significantly better, p<0.05) for closer than further targets in Normal and Level-Only conditions. On the contrary, in the Equalized condition, these thresholds were lower for further than closer targets. Thresholds were lower at higher reverberation in the Equalized condition, and for further targets in the Normal condition. Data indicate that level generally provided more accurate discrimination information than direct-to-reverberant ratio. Direct-to-reverberant ratio provided better information for sounds further from the listener than for nearer sounds, and listeners were able to use direct-to-reverberant ratio as effectively as level in highly reverberant rooms when discriminating far sound sources.