Forward-masked intensity discrimination: Duration effects and spectral effects

Abstract

Three experiments were completed to examine the effect of masker duration and spectrum on forward-masked intensity discrimination. Four listeners participated in each experiment. Intensity discrimination was measured in quiet and in the presence of forward maskers using adaptive forced-choice procedures. The standard duration was either short (10 ms) or long (250 ms) in experiment 1 and short (10 ms) in experiment 2. The standard always occurred 100 ms after the offset of the masker. In the first experiment employing 1.0-kHz maskers and standards, a short duration masker (10 ms) produced more masking than a long duration masker (250 ms). A mid-level elevation of the Weber fraction was observed for all conditions. To ensure that the results of experiment 1 were not influenced by off-frequency listening, the second experiment employed a broadband noise masker. As before, a short duration (10 ms) masker produced more masking than a long duration masker (100 ms) and a mid-level elevation of Weber fractions was observed. This outcome is inconsistent with a peripheral sensory effect for which an increase in masker duration should result in a greater amount of adaptation, and, as a consequence more masking. A third experiment employing a broadband noise masker and standard showed the greatest amount of masking for low-level standards, but only when the duration of the masker and standard was short. This result is similar to one seen for a single listener in the first experiment for short duration tonal maskers and standards. For this listener, a second tone presented at 4.133 kHz presented simultaneously with the 1.0 kHz masker reduced significantly the amount of masking for low-level standards, but the mid-level elevation of the Weber fraction remained. Taken together, these results suggest that perceptual similarity plays a role in forward-masked intensity discrimination but does not account entirely for the mid-level elevation of the Weber fraction.

Binaural release from masking in forward-masked intensity discrimination: Evidence for effects of selective attention

“…Compatible with this prediction, in both experiments by Oberfeld and Stahn (in press) the elevation of the intensity DL caused by the maskers was significantly smaller in conditions favoring the processing of maskers and targets as separate auditory objects or streams. Results from studies demonstrating that reducing the perceptual similarity between masker and target also reduces the masker-induced DLelevation (Schlauch et al, 1999(Schlauch et al, , 1997Oberfeld, 2008) would be directly compatible with the proposed framework of selective attention, while the three models introduced above cannot account for similarity effects without modifications (cf. Oberfeld, 2008).…”

“…Previous experiments from our lab also found DL-elevations in the vicinity of 12 dB for a 60 dB SPL target presented together with an ipsilateral monaural masker (Oberfeld, 2008;Oberfeld and Stahn, in press). As discussed by Oberfeld (2008), smaller DL-elevations are observed if masker and target differ in spectrum or duration (Schlauch et al, 1997;Zeng et al, 1991).…”

“…In particular, for listener 4 the DL-elevation caused by the ipsilateral 90 dB SPL masker was very high at the 30 dB SPL target level. Several previous studies also reported that some listeners exhibit such a pattern instead of the mid-level hump found for the majority of listeners (Oberfeld, 2008;Oberfeld and Stahn, in press;Carlyon and Beveridge, 1993;Zeng et al, 1991;Schlauch et al, 1999Schlauch et al, , 1997. Listener 4 very strongly benefited from the contralateral presentation of the masker.…”

“…The effect of the lateralization difference could be viewed as yet another example that the similarity between masker and standard affects the masker-induced DL-elevation (Schlauch et al, 1999(Schlauch et al, , 1997Oberfeld, 2008). There is of course a strong link between similarity and object formation because according to Gestalt laws similarity is one attribute among others (like proximity) influencing the grouping of elements into one object (for an application to the auditory domain see Kubovy and Van Valkenburg, 2001).…”

Masking effect of different durations of forward masker sound on acoustical responses of mouse inferior collicular neurons to probe sound

“…Previous behavioral tests conducted on humans have shown that different durations of forward masker have different masking effects on the discrimination of probe intensity (Schlauch et al, 1997;Oxenham and Plack, 2000). So far, however, there is little literature available on its neuronal mechanism.…”