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The onset-time difference ΔT required to lateralize a 30-ms bifrequency tone burst toward the leading ear was measured as a function of the frequency difference ΔF between the tone in the left ear and the tone in the right ear. At center frequencies of 0.5 and 4 kHz, four normal listeners tested at 80 and 100 dB SPL had ΔTs that were relatively constant at subcritical ΔFs, but increased at ΔFs wider than a critical band. At 1 kHz, ΔT increased with ΔF even at subcritical ΔFs. Ten listeners with cochlear impairments were tested at 100 dB SPL. Seven had normal ΔTs at 4 kHz, despite hearing losses between 50 and 70 dB. At 0.5 and 1 kHz, mildly impaired listeners had nearly normal lateralization functions, whereas more severely impaired listeners had very large ΔTs and no frequency selectivity. These and other findings indicate that listeners even with moderate to severe hearing losses can lateralize normally on the basis of interaural differences in onset envelope, but not on the basis of temporal differences in the fine structure. [ABSTRACT FROM AUTHOR]

This paper examines how intensity discrimination depends on the test frequency, the level, and the subjects's high-frequency hearing. Three experiments were performed. In the first experiment, intensity discrimination of pulsed tones was measured as a function of level at 1 and 14 kHz in five listeners. Results show less deviation from Weber's law at 14 kHz than at 1 kHz. In the second experiment, intensity discrimination was measured for a 1-kHz tone at 90-dB SPL as a function of the cutoff frequency of a high-pass masking noise in two listeners. Results show that the audibility of very high frequencies is important for frequency discrimination at 1 kHz. The DL increased by a factor between 1.5 and 2.0 as the cutoff frequency of the noise was lowered from 19 to 6 kHz. In the third experiment, thresholds from 6 to 20 kHz and intensity discrimination for a 1-kHz tone was measured in 12 listeners. Results show that the DLs at 80-dB SPL are correlated with the ability to hear very high frequencies. Results of all three experiments are consistent with the multiband version of the excitation-pattern model for intensity discrimination [Florentine and Buus, J. Acoust. Soc. Am. 70, 1646-1654 (1981)]. [ABSTRACT FROM AUTHOR]

Psychoacoustical tuning curves and interaural pitch matches were measured in a listener with a unilateral, moderately severe hearing loss of primarily cochlear origin below 2 kHz. The psychoacoustical tuning curves, measured in a simultaneous-masking paradigm, were obtained at 1 kHz for probe levels of 4.5-, 7-, and 13-dB SL in the impaired ear, and 7-dB SL in the normal ear. Results show that as the level of the probe increased from 4.5- to 13-dB SL in the impaired ear, (1) the frequency location of the tip of the tuning curve decreased from approximately 2.85 to 2.20 kHz and (2) the lowest level of the masker required to just mask the probe increased from 49- to 83-dB SPL. The tuning curve in the normal ear was comparable to data from other normal listeners. The interaural pitch matches were measured from 0.5 to 6 kHz at 10-dB SL in the impaired ear and approximately 15- to 20-dB SL in the normal ear. Results show reasonable identity matches (e.g., a 500-Hz tone in the impaired ear was matched close to a 500-Hz tone in the normal ear), although variability was significantly greater for pitch matches below 2 kHz. The results are discussed in terms of their implications for models of pitch perception. [ABSTRACT FROM AUTHOR]

This paper evaluates two different versions of Zwicker [Acustica 6, 365-381 (1956)] and Maiwald's [Acustica 18, 193-207 (1967)] excitation-pattern model for intensity discrimination. The single-band version is that originally used by Zwicker and Maiwald. They assumed that performance was determined by the critical band in which the excitation grows most rapidly with increasing level of the stimulus. The multiband version forms an optimum decision based on information in all critical bands. Predictions from the two versions of the model are compared to data for intensity discrimination of tones as a function of level and frequency, for partially masked tones and for white noise. In general, the single-band version yields predictions in qualitative agreement, but not in quantitative agreement with the intensity-resolution data for pulsed tones. The multiband version yields predictions in good qualitative as well as quantitative agreement with the data, except at high frequencies. [ABSTRACT FROM AUTHOR]

The purpose of this study was twofold: to determine if the measured loudness level of a signal depends on the standard stimulus used and to measure loudness as a function of the number of components in a wide-band signal. The stimuli were a pure tone, tone complexes with frequency separations of 231 and 1592 Hz, and noise bands with widths of 220 and 1592 Hz. The center frequency was 1 kHz and the loudness level was approximately 65 phons. Loudness matches between all combinations of stimuli showed that the measured loudness of the sounds did not depend on the standard stimulus used and the measured loudness level of a wide-band sound increased as a function of the number of components. Individual observers were consistent in their loudness estimations; the greatest source of variability was among subjects. Additional measurements indicated that the rate at which loudness increased beyond the critical band appeared to be greater for noise bands than for two-tone complexes. [ABSTRACT FROM AUTHOR]

The minimum detectable gap MDG in a low-pass (fc = 7 kHz) noise was measured monaurally as a function of level in listeners with normal hearing, hearing impairments of primarily cochlear origin, and impairments simulated by masking. The listener judged which of two intervals, marked by lights, contained the gap and a modified BUDTIF procedure was used to measure the MDG. The results for normal listeners agree with previous data. Results for seven impaired listeners indicate that in most cases their MDGs depend on their high-frequency thresholds. For example, at high levels, one listener with a low-frequency impairment had nearly normal MDGs, whereas listeners with high-frequency impairments showed enlarged MDGs. Most of the reduction in temporal acuity could be produced by presenting a normal listener with a masking noise spectrally shaped to simulate the audiogram. However, for two impaired listeners with almost identical audiograms, one listener's performance could be simulated well by masking a normal ear, but the other's MDGs were worse than the simulation by a factor 1.5 at the high levels. These results indicate that temporal acuity, per se, may be reduced in some, but not all, impaired listeners. [Work supported by NIH Grant RR07143 and the RSDF of Northeastern University.] [ABSTRACT FROM AUTHOR]

This letter reanalyzes data from the literature in order to test two loudness-growth models for listeners with hearing losses of primarily cochlear origin: rapid growth and softness imperception. Five different studies using different methods to obtain individual loudness functions were used: absolute magnitude estimation, cross-modality matching with string length, categorical loudness scaling, loudness functions derived from binaural loudness summation, and loudness functions derived from spectral summation of loudness. Results from each of the methods show large individual differences. Individual loudness-growth functions encompass a wide range of shapes from rapid growth to softness imperception. [ABSTRACT FROM AUTHOR]

To investigate the dependence of comodulation masking release (CMR) on the type and frequency of modulator, thresholds were measured for a 4-kHz tone masked by modulated and unmodulated noises. The maskers were a 400-Hz wideband of noise centered on 4 kHz (NOCUE), the same noise with a 2700-Hz low-pass noise added (LPCUE), and a wideband noise with a passband between 3 and 6 kHz (WBCUE). Each modulated masker was presented with several modulation frequencies, fes and three types of modulators: a square wave, a sinewave, and a low-pass noise. Thresholds were lower in the presence than in the absence of modulation for all modulator types, except when fe was high. The modulated-unmodulated difference (MUD) decreased monotonically with increasing fe in all conditions. For any given fe, MUDs were greater for square-wave and low-pass-noise modulation than for sinusoidal modulation. The CMR, defined as the difference between the MUD obtained in the NOCUE condition and that obtained in each cue condition, did not vary systematically with fe over the range studied. CMR was smaller for sinusoidal modulation than for either square-wave or low-pass-noise modulation. Although there was some variability across listeners, low-pass-noise modulators that produced an fe of between 32 and 100 Hz resulted in substantial (5-9 dB) CMRs for all three listeners. [Work supported by the Piggott-Wernher Fellowship and NIH.] [ABSTRACT FROM AUTHOR]

It is well known that a tone presented binaurally is louder than the same tone presented monaurally. It is less clear how this loudness ratio changes as a function of level. The present experiment was designed to directly test the Binaural Equal-Loudness-Ratio hypothesis (BELRH), which states that the loudness ratio between equal-SPL monaural and binaural tones is independent of SPL. If true, the BELRH implies that monaural and binaural loudness functions are parallel when plotted on a log scale. Cross-modality matches between string length and loudness were used to directly measure binaural and monaural loudness functions for nine normal listeners. Stimuli were 1-kHz 200-ms tones ranging in level from 5 dB SL to 100 dB SPL. A two-way ANOVA showed significant effects of level and mode (binaural or monaural) on loudness, but no interaction between the level and mode. Consequently, no significant variations were found in the binaural-to-monaural loudness ratio across the range of levels tested. This finding supports the BELRH. In addition, the present data were found to closely match loudness functions derived from binaural level differences for equal loudness using the model proposed by Whilby et al. [J. Acoust. Soc. Am. 119, 3931–3939 (2006)]. [ABSTRACT FROM AUTHOR]