The Effects of Duration and Level on Spectral Modulation Perception

Abstract

Purpose Spectral modulation detection is an increasingly common assay of suprathreshold auditory perception and has been correlated with speech perception performance. Here, the potential effects of stimulus duration and stimulus presentation level on spectral modulation detection were investigated. Method Spectral modulation detection thresholds were measured as a function of modulation frequency in young, normal-hearing listeners. The standard stimulus was a bandpass noise, and signal stimuli were created by superimposing sinusoidal spectral modulation on the bandpass noise carrier. The modulation was sinusoidal on a log 2 frequency axis and a log 10 (dB) amplitude scale with a random starting phase (0–2π radians). In 1 experiment, stimulus durations were 50, 100, 200, or 400 ms (at fixed level 81 dB SPL). In a 2nd experiment, stimuli were presented at sensation levels of 10, 20, 30, 40, and 60 dB SL (fixed at a duration of 400 ms). Results Spectral modulation detection thresholds were similarly low for the 400- and 200-ms durations, increased slightly for the 100-ms duration, and increased markedly for the 50-ms duration. Thresholds were lowest for 40 dB SL; increased slightly for 20, 30, and 60 dB SL; and markedly higher for the 10–dB SL condition. Conclusions The increase in thresholds for the shortest durations and lowest sensational levels is consistent with previous investigations of auditory spectral profile analysis. The effects of presentation level and stimulus duration are important considerations in the context of understanding potential relationships between the perception of spectral cues and speech perception, when designing investigations and interpreting data related to spectral envelope perception, and in the context of models of auditory perception. As examples, 2 simple models based on auditory nerve output that have been used to explain spectrotemporal modulation in previous investigations produced an output inconsistent with the present results. Plain language summary Intensity variations across audio frequency lead to spectral shapes that are essential and sometimes signature features of various sounds in the environment, including speech. Here, we show how laboratory measures of spectral shape perception depend on presentation level and stimulus duration.

Audibility and Spectral-Ripple Discrimination Thresholds as Predictors of Word Recognition with Nonlinear Frequency Compression

“…58 Evidence supporting the influence of audibility to ripple perception includes the observations that RPO thresholds decrease at low sensation levels, and individuals with higher aided SII values have better RPO thresholds. Specifically, the perception of rippled noise is known to degrade at low sensation levels, 36 40 ostensibly due to a combination of inaudibility of ripple nulls or portions of the spectrum at low sensation levels; consequently, the participants with a lower aided SII in this study and in Kirby et al 37 might have been less able to resolve spectral peaks due to inaudibility. While Kirby et al 59 did not find a relationship between aided SII and RPO thresholds, the use of participants with high levels of audibility (mean aided SII = 78) may have limited the observed relationship of RPO to aided SII in that study.…”

“…Auditory filter bandwidth increases as degree of HL increases, in turn leading to reduced distinctness of spectral peaks and poorer perception of spectral ripples. 9 36 40 60 Because auditory filter bandwidths are wider at high presentation levels, RPO thresholds decline for elevated presentation levels. 36 40 Consider that the prescribed gain was higher for those with greater HL, resulting in a higher presentation level than for those with lessor HL.…”

“…9 36 40 60 Because auditory filter bandwidths are wider at high presentation levels, RPO thresholds decline for elevated presentation levels. 36 40 Consider that the prescribed gain was higher for those with greater HL, resulting in a higher presentation level than for those with lessor HL. Therefore, the use of a higher presentation level may have contributed to poorer ripple thresholds for those with poorer audibility.…”

“…37 Due to inaudibility of the dips or portions of the noise spectrum, the ability to perceive spectral ripples degrades at low sensation levels and, presumably due to widening of the auditory filters, degrades again at high-sensation levels. 36 40…”

The effect of stimulus duration on preferences for gain adjustments when listening to speech

“…There is some evidence of a duration effect with broadband stimuli: studying the detection of an 8-dB peak at 3.5 kHz in a broadband noise, Farrar et al (1987) found that thresholds decreased as duration increased up to 300 ms, the maximum duration tested. Isarangura et al (2019) found that the detection of spectral modulation in a broadband noise carrier also improved with increasing duration but reached asymptote by 200 ms. For speech stimuli, measures of duration effects on level discrimination are scant; in a study of overall level discrimination of speech, the threshold for words (mean duration 450 ms) was only significantly worse (greater) than for sentences (mean duration 1533 ms) when participants were aided (Whitmer and Akeroyd, 2011).…”