Detection of Auditory Signals in Reproducible Noise

Abstract

Twelve reproducible noises were used as stimuli in a 2-interval forced-choice signal-detection experiment. The noises were stored numerically in a PB250 computer that converted thein to sound during the experiment by means of a digital-to-analog converter. The 240 numbers specifying a noise were sampled at a rate of 2500 numbers/sec, generating a 96-msec stimulus. A sinusoidal signal with a period of 8 samples/cycle was added to one noise on half the trials. Spectral analyses were computed for all stimuli. On nonsignal trials, biases to particular noises were found that could be explained in part, but not entirely, by differences between the noise pairs in energy around the signal frequency. Performance on signal trials was related to the energy difference between the stimuli in the region near the signal frequency, but was not entirely accounted for by this variable. Special characteristics of certain noises appear to affect the subject's response when these noises appear in either signal or nonsignal trials. Except for bias effects, detection on signal trials with the same noise in both intervals was similar to that on trials with different noises. Implications for theories of signal detection are discussed.

Binaural detection with narrowband and wideband reproducible noise maskers. III. Monaural and diotic detection and model results

“…Model sensitivity was slightly higher for narrowband stimuli ͑dЈ = 1.45͒ than for wideband stimuli ͑dЈ = 1.39͒, however both of the resulting dЈ values were consistent with what would be expected for a model with no internal noise ͑i.e., dЈ Ϸ ͱ 2, as described above͒. The finding that stimulus energy was related to subject responses is consistent with previous studies ͑e.g., Pfafflin and Mathews, 1966;Ahumada et al, 1975;Gilkey and Robinson, 1986͒. Critical-band model predictions were significant for all subjects in all conditions; however, a substantial portion of the variance in the average subject's detection pattern was unaccounted for under wideband conditions.…”

How much masking is informational masking?

“…Another source of masking, not often discussed in these studies, is that resulting from the uncertainty associated with trial-to-trial variation in the noise waveform (cf. Pfafflin and Mathews, 1966). Pollack ( 1975 ) uses the term informational masking to describe this second type of masking.…”

Models of auditory masking: A molecular psychophysical approach

“…The first study to employ this type of quasimolecular approach was that of Pfafflin and Mathews (1966). They investigated the detectability of a 312.5-Hz sinusoidal signal that was masked by each of 12 bursts of computer-generated noise.…”