The loudness of sounds that increase and decrease continuously in level

Abstract

A sound at a low level is heard as much softer after having decreased continuously from higher levels than if presented after a period of silence at that same low level. Canévet [Acustica 61, 256-264 (1986)] demonstrated this phenomenon for a tone that (1) decreased from 65 to 20 dB in 180 s; he also presented a tone that (2) increased from 20 dB, or (3) was presented as pairs of bursts at various levels in random order. Below about 40 dB, loudness changed most rapidly in the decreasing condition so that, at 20 dB, the tone was judged ten times softer than in conditions (2) and (3). In the present experiments, magnitude estimation was used to examine the possible role of judgmental biases and adaptation in this rapid loudness decline, which we call decruitment. Results show that decruitment did not come about because subjects made many successive loudness judgments; loudness declined as much when a tone was judged only twice, at the beginning and end of its 180-s decrease. In contrast, interrupting the decreasing tone so that it was heard only at 70 dB and 160 s later at 30 dB greatly diminished the decruitment. Similarly, pairs of 500-ms tone bursts presented at successively lower levels instead of continously decreasing did not show decruitment, suggesting that sequential biases are irrelevant. The likely cause of decruitment is sensory adaptation.

Comparison of loudness models for time-varying sounds

“…Temporal asymmetries such as found by Stecker and Hafter [44] were also observed for markedly longer stimuli (e.g. [63,64,65,66,67,68]). Fore xample, Susini et al [68] found that sounds with increasing levell ead to greater global loudness judgments than sounds with decreasing levelf or durations between 2a nd 20 s. Theyp roposed "that global impressions resulted from amemory process dominated by the last parts of the sound sequence" [68].…”

Sweep-induced acceleration in loudness change and the “bias for rising intensities”

“…The early studies of SIF (e.g., Canévet & Scharf, 1990) included a control condition in which the start and end levels of the downsweep were presented discretely, with an intervening silent period corresponding to the duration of the sweep. The difference between the judgments of the end level with and without a sweep was taken as a measure of SIF.…”

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A pure tone changing continuously in intensity shows sweep-induced fading (SIF) of loudness as intensity sweeps down and may show a lesser degree of sweep-induced enhancement (SIE) as intensity sweeps up (Canévet & Scharf, 1990); the former effect has been called decruitment, the latter upcruitment. An opposite effect-upsweeps being judged to show more loudness change than downsweeps-has been reported by Neuhoff (1998).

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“…Yet Schlauch has also shown that the magnitude of the effect is diminished when the listener performs a second, distracting task, suggesting that we are dealing with a peripheral process governed, to some extent, by a central factor, attention. Theoretical speculation about SIF has focused primarily on various forms of adaptation (e.g., Canévet & Scharf, 1990; but see also Teghtsoonian et al, 2000), although there is still no definitive account of the process and how it occurs. Despite this uncertainty, the empirical phenomenon is robust and striking in its magnitude: A 40-dB 1-kHz tone heard at the end of a 20-sec downsweep starting at 70 dB will sound only about a quarter as loud as that same tone heard alone.…”

The subjective duration of ramped and damped sounds

“…Although pairs of such sounds have identical overall spectral contents, durations, levels, and absolute changes in level, many perceptual attributes of the sounds are strikingly different. Ramped and damped sounds differ in timbre (Akeroyd & Patterson, 1995;Irino & Patterson, 1996;Patterson, 1994aPatterson, , 1994b, subjective duration (Schlauch, Ries, & DiGiovanni, 2001), overall loudness (Stecker & Hafter, 2000), and possibly changes in loudness (for durations shorter than ~2 sec, see Neuhoff, 1998Neuhoff, , 2001Seifritz et al, 2002; for longer durations, see Canévet, 1986;Canévet & Scharf, 1990;Canévet, Teghtsoonian, & Teghtsoonian, 2003;Schlauch, 1992;Teghtsoonian, Teghtsoonian, & Canévet, 2000, 2005. The explanation for these effects is not yet clear, with differences in sensory coding providing a possible explanation for brief sounds but not for longer ones.…”