Does Auditory Similarity Affect the Usefulness of Cues to Perceived Relative Distance?

Abstract

This study investigated the effects of auditory similarity on cues to relative distance. Vision literature has suggested that some common visual illusions involving size contrast depend on certain physical or conceptual characteristics of the objects involved. In short, objects judged to be similar exhibit greater size contrast than objects judged to be dissimilar. This study looked at whether the same principles of similarity might also hold true for auditory distance perception. Specifically, if sounds are more similar, are they more likely to be compared to one another than are dissimilar sounds? If they are, and there are cues to relative distance available, the cues between similar sounds might be stronger. In this study, sounds were varied in spectral content, wave envelope and sound level. The stimuli consisted of 27 different sound pairs. The first sound in each pair was a broadband reference sound. The second sound was a comparison sound that varied in one of 27 different ways from the reference sound (spectral content being the same, higher, or lower; wave envelope being the same, backwards, or random; and sound level being the same, higher, or lower). The sounds were presented from a small loudspeaker located 2.5 meters in front of the listener in an acoustically 'dead' room. Participants consisted of 40 students from a course in introductory psychology (20 men and 20 women) with a median age of 20. The participants used a magnitude estimation task to report perceived relative distance between the reference and comparison sounds in each sound pair. After all of the sound pairs were presented, the reference sound was presented once more by itself (either forwards or backwards). Participants gave a verbal judgment of the distance of the reference sound from themselves (i.e., an egocentric distance). The results of the study suggest that envelope and spectral content interact with sound level in determining perceived distance. Cues to relative distance were affected by 'auditory similarity,' but not in a systematic way. Recommendations for future research are made.