Influence of Signal Duration on the Masking-Level Difference

1987 ◽  
Vol 30 (3) ◽  
pp. 330-334 ◽  
Author(s):  
Richard H. Wilson ◽  
Ruth A. Fugleberg
Keyword(s):  
Forced Choice ◽  
Broadband Noise ◽  
Signal Duration ◽  
Spectrum Level ◽  
Level Difference ◽  
Masking Level Difference ◽  
Choice Method

The effect of signal duration on the 500-Hz masking-level difference was studied in 4 subjects using an adaptive, two-interval, forced-choice method. S o N o , S π N o , and S o N π thresholds for 13 signal durations between 2 and 100 ms were established incontinuous broadband noise (36.2 dB pressure-spectrum level). The signals were synthesized and gated digitally with 1-ms rise-fall times. The S o N o threshold integration functions diverged from the S π N o or the S o N π threshold integration functions as the signal duration was reduced from 100 ms to 6–10 ms. As the signal duration was reduced below 6–10 ms, however, the threshold integration functions for S o N o , S π N o , and S o N π converged. The relationships among the threshold integration functions were reflected in the S o N o -S π N o and the S o N o -S o N π masking-level differences that increased as the signal duration was reduced from 100 to 6–10 ms and then decreased as the signal duration was reduced below 6–10 ms.

scholarly journals Responses of Neurons in the Inferior Colliculus to Binaural Masking Level Difference Stimuli Measured by Rate-Versus-Level Functions

1997 ◽  
Vol 77 (6) ◽  
pp. 3085-3106 ◽  
Author(s):  
Dan Jiang ◽  
David McAlpine ◽  
Alan R. Palmer
Keyword(s):  
Inferior Colliculus ◽  
Discharge Rate ◽  
Detection Threshold ◽  
Low Frequency ◽  
Broadband Noise ◽  
Coincidence Detection ◽  
Level Difference ◽  
Rate Versus ◽  
Versus Level ◽  
Masking Level Difference

Jiang, Dan, David McAlpine, and Alan R. Palmer. Responses of neurons in the inferior colliculus to binaural masking level difference stimuli measured by rate-versus-level functions. J. Neurophysiol. 77: 3085–3106, 1997. The psychophysical detection threshold of a low-frequency tone masked by broadband noise is reduced by ≤15 dB by inversion of the tone in one ear (called the binaural masking level difference: BMLD). The contribution of 120 low-frequency neurons (best frequencies 168–2,090 Hz) in the inferior colliculus (ICC) of the guinea pig to binaural unmasking of 500-Hz tones masked by broadband noise was examined. We measured rate-level functions of the responses to identical signals (So) and noise (No) at the two ears (NoSo) and to identical noise but with the signal inverted at one ear (NoSπ): the noise was 7–15 dB suprathreshold. The masked threshold was estimated by the standard separation, “D”. The neural BMLD was estimated as the difference between the masked thresholds for NoSo and NoSπ. The presence of So and Sπ tones was indicated by discharge rate increases in 55.3% of neurons. In 36.4% of neurons, the presence of So tones was indicated by an increase in discharge rate and Sπ tones by a decrease. In 6.8% of neurons, both So and Sπ tones caused a decrease in discharge rate. In only 1.5% of neurons was So indicated by a decrease and Sπ by an increase in discharge rate. Responses to the binaural configurations were consistent with the neuron's interaural delay sensitivities; 34.4% of neurons showing increases in discharge rate to both So and Sπ tones gave positive BMLDs ≥3 dB (Sπ tones were detected at lower levels than So), whereas 37.3% gave negative BMLDs ≥3 dB. For neurons in which So signals caused an increase in the discharge rate and Sπ a decrease, 72.7% gave positive BMLDs ≥3 dB and only 4.5% gave negative BMLDs ≥3 dB. The results suggest that the responses of single ICC neurons are consistent with the psychophysical BMLDs for NoSo versus NoSπ at 500 Hz, and with current binaural interaction models based on coincidence detection. The neurons likely to contribute to the psychophysical BMLD are those with BFs near 500 Hz, but detection of So and Sπ tones may depend on different populations of neurons.

Development of a 500-Hz Masking-Level Difference Protocol for Clinic Use

2003 ◽  
Vol 14 (01) ◽  
pp. 001-008 ◽  
Author(s):  
Richard H. Wilson ◽  
Deborah W. Moncrieff ◽  
Elizabeth A. Townsend ◽  
Amanda L. Pillion
Keyword(s):  
Normal Hearing ◽  
Signal To Noise ◽  
Spectrum Level ◽  
Level Difference ◽  
Masking Level Difference ◽  
Single Interval ◽  
Series Of Experiments ◽  
The Mean ◽  
Perceptual Abilities ◽  
Response Task

The purpose of this series of experiments was to develop a simple, 500-Hz masking-level difference (MLD) protocol that could be implemented easily in the clinic to assess auditory perceptual abilities using an audio compact disc. Five, 300-ms tones with 250-ms intertone intervals were embedded in 3-s bursts of 200-800 Hz noise presented at 42.2-dB pressure-spectrum level with 4-5 s inter-stimulus intervals. The homophasic and antiphasic conditions were interleaved with the signal-to-noise ratios decreasing in 2-dB steps. A single-interval, "yes/no" response task was used. Three experiments were performed on 24-28 listeners with normal hearing. The mean SoNo thresholds (58.1- to 59.5-dB SPL) and the mean SπNo thresholds (45.1- to 46.0-dB SPL) produced ˜13-dB MLDs. Experiment 3 included a SoNπ condition that had a mean threshold of 48.8-dB SPL and a 10.0-dB MLD. The mean test, retest ot the SoNo and SπNo thresholds on 15 listeners was <0.5 dB. Over the three experiments, 95% of the listeners had SπNo MLDs that were ≥10 dB.

Masking-Level Difference in Filtered-Random and Amplitude-Modulated Noise

1984 ◽  
Vol 27 (2) ◽  
pp. 267-274 ◽  
Author(s):  
Richard H. Wilson ◽  
John T. Argos ◽  
Carolyn J. Brown ◽  
Leslie A. Bennett
Keyword(s):  
Power Spectrum ◽  
Random Noise ◽  
Spectrum Level ◽  
Zero Crossings ◽  
Level Difference ◽  
Masking Level Difference ◽  
Filtered Noise

The masking characteristics of filtered-random noise and amplitude-modulated noise (40-dB pressure-spectrum level) were studied in a series of four experiments using a masking-level difference paradigm, that is, 500-Hz thresholds in S o N o and S π N o binaural conditions. In Experiment 1 a filtered noise (200–800 Hz) and an amplitude-modulated noise (425–575 Hz) produced equal thresholds in S o N o ; for S π N o , however, the thresholds in amplitude-modulated noise were 1.6 dB lower than were the thresholds in filtered noise. In Experiment 2 S o N o and S π N 0 thresholds were established in three filtered noise bandwidths (200–800 Hz, 335–685 Hz, and 410–600 Hz) and in the amplitude-modulated noise (425–575 Hz). When the bandwidths of the filteredrandom and amplitude-modulated noises were similar, the SπN o thresholds were the same but the S o N o thresholds were different. Experiments 3 and 4 indicated that with amplitude-modulated noise when the zero amplitude crossings of the tone and the noisecoincided, the S o N o , SπN o , and S m N m thresholds were 1.2–2.0 dB higher than were the thresholds when the zero crossings of the tone and noise did not coincide. The data indicate that the masking characteristics of filtered-random noise and amplitudemodulated noise are different. The findings are interpreted as an indication that perceptual phenomena depend on the temporal characteristies as well as the power spectrum of the signal and masker.

Effects of Signal Duration on the 500-HZ Masking-Level Difference

1986 ◽  
Vol 15 (4) ◽  
pp. 209-215 ◽  
Author(s):  
Richard H. Wilson ◽  
Cynthia G. Fowler
Keyword(s):  
Signal Duration ◽  
Level Difference ◽  
Masking Level Difference

The effect of diotic and dichotic level-randomization on the binaural masking-level difference

2005 ◽  
Vol 118 (5) ◽  
pp. 3229-3240 ◽  
Author(s):  
G. Bruce Henning ◽  
Virginia M. Richards ◽  
Jennifer J. Lentz
Keyword(s):  
Level Difference ◽  
Masking Level Difference

Forced-Choice vs Free-Response in Personality Assessment

1963 ◽  
Vol 13 (1) ◽  
pp. 159-169 ◽  
Author(s):  
Peter F. Merenda ◽  
Walter V. Clarke
Keyword(s):  
Personality Assessment ◽  
Forced Choice ◽  
Self Concept ◽  
Personality Profiles ◽  
Psychological Measurement ◽  
Free Response ◽  
Relative Validity ◽  
General Consensus ◽  
Choice Method ◽  
Statistical Results

Two self-rating adjective check lists (ACL) were administered to 44 students in a course on psychological measurement. The first ACL administered was the regular free response list, followed immediately with a forced-choice version in which the adjectives were arranged into tetrad sets. Ipsative scoring was used and profiles compared. The correlations between the profiles ranged from −1.00 to 1.00, more than 40% falling in the negative range. Ss gave their impressions and reactions to both inventories, and evaluated the relative validity of the results. A majority favored the free-response technique and felt that it would yield a more accurate description of their self-concepts and personality structures. General consensus was that the forced-choice instructions led to frustration, increased irritability, and decreased motivation. Ss felt that the free-response instrument presented a more relaxing situation and was even enjoyable to take. Ss' verbal reactions were consistent with the statistical results. The findings suggest that the forced-choice method is likely to be inappropriate for use with adjective check lists in self-concept assessment and analysis, and may lead not only to distortion in the personality profiles, but also to reversals.

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