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Apr 2010

Volume 127, Issue 4, pp. EL121-2714

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The loudness of sounds whose spectra differ at the two ears

Brian R. Glasberg and Brian C. J. Moore

J. Acoust. Soc. Am. Volume 127, Issue 4, pp. 2433-2440 (2010); (8 pages) | Cited 2 times

Online Publication Date: 05 Apr 2010

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Moore and Glasberg [(2007). J. Acoust. Soc. Am. 121, 1604–1612] developed a model for predicting the loudness of dichotic sounds. The model gave accurate predictions of data in the literature, except for an experiment of Zwicker and Zwicker [(1991). J. Acoust. Soc. Am. 89, 756–764] , in which sounds with non-overlapping spectra were presented to the two ears. The input signal was noise with the same intensity in each critical band (bark). This noise was filtered into 24 bands each 1 bark wide. The bands were then grouped into wider composite bands (consisting of 1, 2, 4, or 12 successive sub-bands) and each composite band was presented either to one ear or the other. Loudness estimates obtained using a scaling procedure decreased somewhat as the number of composite bands increased (and their width decreased), but the predictions of the model showed the opposite pattern. This experiment was similar to that of Zwicker and Zwicker, except that the widths of the bands were based on the ERBN-number scale, and a loudness-matching procedure was used. The pattern of the results was consistent with the predictions of the model, showing an increase in loudness as the number of composite bands increased and their spacing decreased.
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43.66.Cb Loudness, absolute threshold
43.66.Pn Binaural hearing
43.66.Ba Models and theories of auditory processes

Excitation-based and informational masking of a tonal signal in a four-tone masker

Lori J. Leibold, Jack J. Hitchens, Emily Buss, and Donna L. Neff

J. Acoust. Soc. Am. Volume 127, Issue 4, pp. 2441-2450 (2010); (10 pages) | Cited 1 time

Online Publication Date: 05 Apr 2010

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This study examined contributions of peripheral excitation and informational masking to the variability in masking effectiveness observed across samples of multi-tonal maskers. Detection thresholds were measured for a 1000-Hz signal presented simultaneously with each of 25, four-tone masker samples. Using a two-interval, forced-choice adaptive task, thresholds were measured with each sample fixed throughout trial blocks for ten listeners. Average thresholds differed by as much as 26 dB across samples. An excitation-based model of partial loudness [ Moore, B. C. J. et al. (1997). J. Audio Eng. Soc. 45, 224–237 ] was used to predict thresholds. These predictions accounted for a significant portion of variance in the data of several listeners, but no relation between the model and data was observed for many listeners. Moreover, substantial individual differences, on the order of 41 dB, were observed for some maskers. The largest individual differences were found for maskers predicted to produce minimal excitation-based masking. In subsequent conditions, one of five maskers was randomly presented in each interval. The difference in performance for samples with low versus high predicted thresholds was reduced in random compared to fixed conditions. These findings are consistent with a trading relation whereby informational masking is largest for conditions in which excitation-based masking is smallest.
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43.66.Dc Masking
43.66.Lj Perceptual effects of sound

The origin of binaural interaction in the modulation domain

Aleksander Sek, Brian R. Glasberg, and Brian C. J. Moore

J. Acoust. Soc. Am. Volume 127, Issue 4, pp. 2451-2460 (2010); (10 pages) | Cited 1 time

Online Publication Date: 05 Apr 2010

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The purpose of these experiments was to assess whether the detection of diotic 5 Hz “probe” modulation of a 4000 Hz sinusoidal carrier was influenced by binaural interaction of “masker” modulators presented separately to each ear and applied to the same carrier. A 50 Hz masker modulator was applied to one ear and the masker modulator applied to the other ear had a frequency of 55 or 27.5 Hz. The starting phase of the masker modulators was fixed, and the starting phase of the probe modulator was varied. For both pairs of masker modulators, the threshold for detecting the probe modulation varied slightly but significantly with probe starting phase. Further experiments measuring probe detectability as a function of probe modulation depth did not provide clear evidence to support the idea that the internal representations of the masker modulators interacted binaurally to produce a weak distortion component in the internal representation of the modulation at a 5 Hz frequency. Also, the obtained phase effects were not correctly predicted using a model based on short-term loudness fluctuations.
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43.66.Dc Masking
43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music
43.66.Nm Phase effects
43.66.Ba Models and theories of auditory processes

The effect of onset asynchrony on relative weights in profile analysis

Jinyu Qian and Virginia M. Richards

J. Acoust. Soc. Am. Volume 127, Issue 4, pp. 2461-2465 (2010); (5 pages) | Cited 1 time

Online Publication Date: 05 Apr 2010

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Decision weights were estimated in a profile analysis task to determine whether onset asynchronies between the signal component and the nonsignal components encourage the segregation of the signal relative to the other components. The signal component onset was either synchronous or asynchronous with respect to the nonsignal components. In the asynchronous conditions, thresholds were higher and the decision weights were less efficient than in the synchronous conditions. These data are largely consistent with a segregation hypothesis: onset asynchrony encourages subjects to shift strategies from one of spectral shape discrimination toward one of intensity discrimination.
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43.66.Fe Discrimination: intensity and frequency
43.66.Ba Models and theories of auditory processes

Combining information across frequency regions in fundamental frequency discrimination

Hedwig E. Gockel, Robert P. Carlyon, and Christopher J. Plack

J. Acoust. Soc. Am. Volume 127, Issue 4, pp. 2466-2478 (2010); (13 pages) | Cited 1 time

Online Publication Date: 05 Apr 2010

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Sensitivity to fundamental frequency (F0) differences was measured for two complex tones, A and B, which had the same F0 but were filtered into two different frequency regions. Tones were presented either alone or together. A signal-detection analysis was used to predict effects of combining F0 information across frequency regions. For 400-ms tones containing only unresolved harmonics, the first experiment showed that performance (in terms of d′) for the combined presentation was better than for the isolated tones but was not optimal (assuming independent channels and noises) and was independent of the relative timing of pulses in the envelopes of tones A and B (varied by changing the starting phase of components of tone B relative to those of tone A). The nonoptimal performance was shown not to be due to peripheral masking (experiment II), or to listeners paying attention mainly to one frequency region (experiment III), nor was it specific to conditions where all harmonics were unresolved (experiment IV). In contrast, optimal performance in F0 discrimination for combined presentation was observed for 50-ms tones (experiment V). The results may reflect the limited ability of the human auditory system to integrate information simultaneously in the time and the frequency domains.
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43.66.Hg Pitch
43.66.Ba Models and theories of auditory processes
43.66.Fe Discrimination: intensity and frequency

Revision, extension, and evaluation of a binaural speech intelligibility model

Rainer Beutelmann, Thomas Brand, and Birger Kollmeier

J. Acoust. Soc. Am. Volume 127, Issue 4, pp. 2479-2497 (2010); (19 pages) | Cited 7 times

Online Publication Date: 05 Apr 2010

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This study presents revision, extension, and evaluation of a binaural speech intelligibility model ( Beutelmann, R., and Brand, T. (2006). J. Acoust. Soc. Am. 120, 331–342 ) that yields accurate predictions of speech reception thresholds (SRTs) in the presence of a stationary noise source at arbitrary azimuths and in different rooms. The modified model is based on an analytical expression of binaural unmasking for arbitrary input signals and is computationally more efficient, while maintaining the prediction quality of the original model. An extension for nonstationary interferers was realized by applying the model to short time frames of the input signals and averaging over the predicted SRT results. Binaural SRTs from 8 normal-hearing and 12 hearing-impaired subjects, incorporating all combinations of four rooms, three source setups, and three noise types were measured and compared to the model’s predictions. Depending on the noise type, the parametric correlation coefficients between observed and predicted SRTs were 0.80–0.93 for normal-hearing subjects and 0.59–0.80 for hearing-impaired subjects. The mean absolute prediction error was 3 dB for the mean normal-hearing data and 4 dB for the individual hearing-impaired data. 70% of the variance of the SRTs of hearing-impaired subjects could be explained by the model, which is based only on the audiogram.
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43.66.Pn Binaural hearing
43.71.An Models and theories of speech perception
43.55.Hy Subjective effects in room acoustics, speech in rooms
43.71.Ky Speech perception by the hearing impaired

Benefits of knowing who, where, and when in multi-talker listening

Pádraig T. Kitterick, Peter J. Bailey, and A. Quentin Summerfield

J. Acoust. Soc. Am. Volume 127, Issue 4, pp. 2498-2508 (2010); (11 pages) | Cited 5 times

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The benefits of prior information about who would speak, where they would be located, and when they would speak were measured in a multi-talker spatial-listening task. On each trial, a target phrase and several masker phrases were allocated to 13 loudspeakers in a 180° arc, and to 13 overlapping time slots, which started every 800 ms. Speech-reception thresholds (SRTs) were measured as the level of target relative to masker phrases at which listeners reported key words at 71% correct. When phases started in pairs all three cues were beneficial (“who” 3.2 dB, “where” 5.1 dB, and “when” 0.3 dB). Over a range of onset asynchronies, SRTs corresponded consistently to a signal-to-noise ratio (SNR) of −2 dB at the start of the target phrase. When phrases started one at a time, SRTs fell to a SNR of −8 dB and were improved significantly, but only marginally, by constraining “who” (1.9 dB), and not by constraining “where” (1.0 dB) or “when” (0.01 dB). Thus, prior information about “who,” “where,” and “when” was beneficial, but only when talkers started speaking in pairs. Low SRTs may arise when talkers start speaking one at a time because of automatic orienting to phrase onsets and/or the use of loudness differences to distinguish target from masker phrases.
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43.66.Rq Dichotic listening
43.66.Pn Binaural hearing
43.71.Gv Measures of speech perception (intelligibility and quality)
43.66.Dc Masking

Auditory temporal-order processing of vowel sequences by young and elderly listeners

Daniel Fogerty, Larry E. Humes, and Diane Kewley-Port

J. Acoust. Soc. Am. Volume 127, Issue 4, pp. 2509-2520 (2010); (12 pages) | Cited 3 times

Online Publication Date: 05 Apr 2010

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This project focused on the individual differences underlying observed variability in temporal processing among older listeners. Four measures of vowel temporal-order identification were completed by young (N = 35; 18–31 years) and older (N = 151; 60–88 years) listeners. Experiments used forced-choice, constant-stimuli methods to determine the smallest stimulus onset asynchrony (SOA) between brief (40 or 70 ms) vowels that enabled identification of a stimulus sequence. Four words (pit, pet, pot, and put) spoken by a male talker were processed to serve as vowel stimuli. All listeners identified the vowels in isolation with better than 90% accuracy. Vowel temporal-order tasks included the following: (1) monaural two-item identification, (2) monaural four-item identification, (3) dichotic two-item vowel identification, and (4) dichotic two-item ear identification. Results indicated that older listeners had more variability and performed poorer than young listeners on vowel-identification tasks, although a large overlap in distributions was observed. Both age groups performed similarly on the dichotic ear-identification task. For both groups, the monaural four-item and dichotic two-item tasks were significantly harder than the monaural two-item task. Older listeners’ SOA thresholds improved with additional stimulus exposure and shorter dichotic stimulus durations. Individual differences of temporal-order performance among the older listeners demonstrated the influence of cognitive measures, but not audibility or age.
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43.66.Sr Deafness, audiometry, aging effects
43.71.Rt Sensory mechanisms in speech perception

Measurement of hearing aid internal noise

James D. Lewis, Shawn S. Goodman, and Ruth A. Bentler

J. Acoust. Soc. Am. Volume 127, Issue 4, pp. 2521-2528 (2010); (8 pages) | Cited 2 times

Online Publication Date: 05 Apr 2010

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Hearing aid equivalent input noise (EIN) measures assume the primary source of internal noise to be located prior to amplification and to be constant regardless of input level. EIN will underestimate internal noise in the case that noise is generated following amplification. The present study investigated the internal noise levels of six hearing aids (HAs). Concurrent with HA processing of a speech-like stimulus with both adaptive features (acoustic feedback cancellation, digital noise reduction, microphone directionality) enabled and disabled, internal noise was quantified for various stimulus levels as the variance across repeated trials. Changes in noise level as a function of stimulus level demonstrated that (1) generation of internal noise is not isolated to the microphone, (2) noise may be dependent on input level, and (3) certain adaptive features may contribute to internal noise. Quantifying internal noise as the variance of the output measures allows for noise to be measured under real-world processing conditions, accounts for all sources of noise, and is predictive of internal noise audibility.
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43.66.Ts Auditory prostheses, hearing aids
43.50.Yw Instrumentation and techniques for noise measurement and analysis
43.58.Ry Distortion: frequency, nonlinear, phase, and transient; measurement of distortion

Wind noise in hearing aids with directional and omnidirectional microphones: Polar characteristics of custom-made hearing aids

King Chung, Nicholas McKibben, and Luc Mongeau

J. Acoust. Soc. Am. Volume 127, Issue 4, pp. 2529-2542 (2010); (14 pages) | Cited 3 times

Online Publication Date: 05 Apr 2010

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The purpose of this study was to examine the characteristics of wind noise at the output of in-the-ear, in-the-canal, and completely-in-the-canal hearing aids. The hearing aids were programed to have linear amplification with matching flat frequency responses for directional (DIR) and omnidirectional (OMNI) microphones. The microphone output was then recorded in a quiet wind tunnel when the Knowles electronic manikin for acoustic research (KEMAR) head was turned from 0° to 360°. The overall, 125, 500, and 2000 Hz one-third octave band flow noise levels were calculated and plotted in polar patterns. Correlation coefficients, average differences, and level differences between DIR and OMNI were also calculated. Flow noise levels were the highest when KEMAR was facing the direction of the flow and angles between 190° and 250°. The noise levels were the lowest when the hearing aids were facing the direction of the flow. The polar patterns of DIR and OMNI had similar shapes and DIR generally had higher levels than OMNI. DIR, however, could have lower levels than OMNI in some angles because of its capability to reduce noise in the far field. Comparisons of polar characteristics with behind-the-ear hearing aids, and clinical and engineering design applications of current results are discussed.
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43.66.Ts Auditory prostheses, hearing aids
43.60.Fg Acoustic array systems and processing, beam-forming
43.38.Kb Microphones and their calibration
43.38.Hz Transducer arrays, acoustic interaction effects in arrays
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