Shrinkage in the perceived duration of speech and tone by acoustic replacement¹

Abstract

To investigate mechanisms for perceiving the duration of an auditory event, an effect of perceptual grouping upon perceived duration was studied psychophysically. In the first experiment, the perceived duration of a spoken word was measured under three conditions of acoustic continuity (i.e., (a) intact, (b) noise-replaced, and (c) gap-replaced) as a function of the duration of the target stimulus. Under the noise-replaced condition, a portion of the target stimulus was physically replaced with a noise burst. Under the gapreplaced condition, the replacement was made with a gap. The gap-replacement resulted in a prominent shrinkage of the perceived duration. In the case of noise-replacement, the amount of shrinkage was moderate but highly significant, although the word employed was perceived to be phonetically intact. Independent of this effect of replacement, the amount of shrinkage was also affected by the physical duration of the target stimulus. The second experiment tested an effect of noise replacement on the perceived duration of a tone burst. In this case, the noise replacement also shrunk the perceived duration of the non-speech stimulus. This noise-induced shrinkage could be regarded as being general for the auditory duration. The phenomenon is discussed in relation to a revised model for perceived duration.

Effects of deviation from isochronism on the durational shrinkage by noise replacement

“…Although several experiments have provided enough counter evidence to refute this hypothesis as a general framework to account for the shrinkage of duration by noise, we cannot deny that contextual information contributes to the perceptual judgment of temporal structure. The results of Tsuzaki and his colleagues also showed that the shifts of PSE depended on a standard duration, and this effect of the standard duration can be regarded as an example of contextual effects [1,3].…”

“…Tsuzaki and his colleagues have demonstrated that the duration of a sound is perceived to be slightly shorter when a portion is replaced by a noise burst than when it is kept intact [1][2][3]. They tested several hypothesis to explain this phenomenon and concluded that the evidence-gating hypothesis is the most acceptable [3].…”

“…They tested several hypothesis to explain this phenomenon and concluded that the evidence-gating hypothesis is the most acceptable [3]. The evidence-gating hypothesis is based on the neural counting mechanism proposed by Creelman [4].…”

“…Another powerful hypothesis rivaling the evidencegating hypothesis is the contextual enhancement hypothesis [3]. It explains the shrinkage phenomena due to noise by an augmented dependancy on contextual information.…”

“…This also supports the conceptual dissociation between an interval and a duration. Furthermore, we can hypothesize that a process for intervals is responsible for the isochronous/contextual effect, as demonstrated by the bias in the perceived duration being dependent on the standard duration [1,3].…”