Modulation and gap detection for broadband and filtered noise signals

Abstract

Modulation detection thresholds (as a function of sinusoidal amplitude modulation frequency) and temporal gap detection thresholds were measured for three low-pass-filtered noise signals (fc = 1000, 2000, and 4000 Hz), a high-pass-filtered noise signal (fc = 4000 Hz), and a broadband signal. The two latter noise signals were effectively low-pass filtered (fc = 6500 Hz) by the earphone. Each of the filtered signals was presented with a complementary filtered noise masker. Modulation and gap detection thresholds were lowest for the broadband and high-pass signals. Thresholds were significantly higher for the low-pass signals than for the broadband and high-pass signals. For these tasks and conditions, the high-frequency content of the noise signal was more important than was the signal bandwidth. Sensitivity (s) and time constant (tau) indices were derived from functions fitted to the modulation detection data. These indices were compared with gap detection thresholds for corresponding signals. The gap detection thresholds were correlated inversely (rho = -1.0, p less than 0.05) with s (i.e., smaller gap detection thresholds were correlated with greater sensitivity to modulation), but were not correlated significantly with tau, which was relatively invariant across signal conditions.

The effects of marker-related temporal cues on auditory gap-duration discrimination

“…However, for the 300-ms markers, the values of T O are much more similar to one another, and relatively large, across values of T G , and ΔT/T O is nearly constant except for the smallest value of T O . The discrepancy at the smallest value of T O may be due to the fact that the corresponding T G is approaching the threshold for the detection of gaps (e.g., Fitzgibbons, 1983;Formby & Muir, 1988) and a different type of decision mechanism (other than duration discrimination) may be involved. Plomp (1964) argued that for gaps less than 10 ms, the auditory sensation of the first marker persists at least until the onset of the second marker.…”

Temporal and speech processing deficits in auditory neuropathy

“…The coef®cient (r) re¯ects the goodness of ®t. A different model by Formby and Muir [25] that has a À3 dB per octave slope was also evaluated and yielded generally higher peak sensitivity values (ranging from À3.9 to À23.1 dB) and lower cutoff frequencies (ranging from 4 Hz to 120 Hz). The goodness of the ®t of this model (r 0.72±0.98) was slightly worse than the ®rst-order Butterworth ®lter.…”

Gap Detection and Temporal Modulation Transfer Function as Behavioral Estimates of Auditory Temporal Acuity Using Band-Limited Stimuli in Young and Older Adults

“…Among the five threshold estimates, three were drawn at random. These three threshold estimates were averaged and then used to fit a first-order low-pass function (Eddins, 1993; Formby & Muir, 1988), from which the TMTF sensitivity ( S ) and cutoff frequency ( f cutoff ) were estimated. The remaining two threshold estimates were averaged and reserved for the purpose of data analysis (see below).…”

“…Formby and Muir (1988) measured the gap detection threshold and the TMTF from six young female listeners using noise carriers with various bandwidths. For each listener, manipulating the carrier bandwidth affected both the gap detection and TMTF results.…”