Biomedical subjects

M Florentine

Publications and source records attributed to M Florentine.

At least 19 recordsLinked to original sources

PubMed2001

Maximum-likelihood yes-no procedure for gap detection: effect of track length.

A maximum-likelihood yes-no procedure was used to measure minimum detectable gaps (MDGs) at 1 and 4 kHz using two track lengths (15 and 30 trials). Results from 11 normal listeners show no difference between MDGs for the two track lengths, and variability of the MDGs did not differ significantly for the track lengths. Results from simulations indicate that the variability of MDGs from real listeners is considerably larger than that imposed by the psychophysical procedure. Additional simulations show that random variability of listeners' response criterion is a compelling explanation for the excess variability. These findings indicate that changes in a listener's threshold over time impose a lower bound on the variability obtainable with a yes-no procedure. They imply that increasing the number of trials in a track, beyond the minimum number required to obtain a stable threshold estimate, offers little or no advantage for the test-retest reliability of a clinical threshold measurement.

Adult↗

PubMed1999

Temporal integration of loudness in listeners with hearing losses of primarily cochlear origin.

To investigate how hearing loss of primarily cochlear origin affects the loudness of brief tones, loudness matches between 5- and 200-ms tones were obtained as a function of level for 15 listeners with cochlear impairments and for seven age-matched controls. Three frequencies, usually 0.5, 1, and 4 kHz, were tested in each listener using a two-interval, two--alternative forced--choice (2I, 2AFC) paradigm with a roving-level, up-down adaptive procedure. Results for the normal listeners generally were consistent with published data [e.g., Florentine et al., J. Acoust Soc. Am. 99, 1633-1644 (1996)]. The amount of temporal integration--defined as the level difference between equally loud short and long tones--varied nonmonotonically with level and was largest at moderate levels. No consistent effect of frequency was apparent. The impaired listeners varied widely, but most showed a clear effect of level on the amount of temporal integration. Overall, their results appear consistent with expectations based on knowledge of the general properties of their loudness-growth functions and the equal-loudness-ratio hypothesis, which states that the loudness ratio between equal-SPL long and brief tones is the same at all SPLs. The impaired listeners' amounts of temporal integration at high SPLs often were larger than normal, although it was reduced near threshold. When evaluated at equal SLs, the amount of temporal integration well above threshold usually was in the low end of the normal range. Two listeners with abrupt high-frequency hearing losses (slopes > 50 dB/octave) showed larger-than-normal maximal amounts of temporal integration (40 to 50 dB). This finding is consistent with the shallow loudness functions predicted by our excitation-pattern model for impaired listeners [Florentine et al., in Modeling Sensorineural Hearing Loss, edited by W. Jesteadt (Erlbaum, Mahwah, NJ, 1997), pp. 187-198]. Loudness functions derived from impaired listeners' temporal-integration functions indicate that restoration of loudness in listeners with cochlear hearing loss usually will require the same gain whether the sound is short or long.

Adult↗

PubMed1999

Psychometric functions for gap detection in a yes-no procedure.

To examine models of temporal resolution and to investigate the decision processes underlying the detection of a brief pause in a bandpass noise, psychometric functions for gap detection were measured at octave frequencies from 0.25 to 8 kHz. Three normal listeners were tested using a constant-stimulus procedure with a cued Yes-No paradigm. The Minimum Detectable Gap (MDG) estimated from the midpoint of the psychometric functions decreased systematically with increasing frequency. The slopes of the psychometric functions generally increased as the test frequency increased up to 2 kHz, but remained constant at the higher frequencies. Two models were investigated: an energy-detector model and a loudness-detector model. Both consisted of auditory filtering, a nonlinearity, and short-term integration. In the energy-detector model, the nonlinearity was a square law. In the loudness-detector model, it was a compressive power law. Using the usual Gaussian approximations, the energy-detector model fails at low frequencies because the probability distributions of short-term energy differ from Gaussian distributions. The probability distributions of short-term loudness closely follow Gaussian distributions. The loudness-detector model predicts the frequency dependence of the MDG quite accurately, except at 0.25 kHz. It also predicts psychometric functions that resemble the data at low frequencies, but the predicted slopes increase much less with frequency than the measured slopes. This result may indicate that the onset response to the trailing marker of the gap provides an important cue for detection of gaps with durations exceeding the MDG.

Adult↗

PubMed1998

On the behavioral characteristics of loud-music listening.

To provide insight into the behavioral characteristics of people who listen excessively to loud music, the 32-item Northeastern Excessive Music Listening Survey was developed and administered to 90 subjects. Results indicate that 8 of the 90 subjects scored within a range that would suggest the presence of a maladaptive pattern of music-listening behavior similar to that exhibited by substance abusers. Implications for further research and models of treatment are discussed.

Adult↗

PubMed1998

On loudness at threshold.

Absolute thresholds for and loudness matches between pure tones and four- and ten-tone complexes were used to assess the form of the function relating loudness to sensation level, SL, at low and moderate levels. The components of the tone complexes had equal SLs and were separated by one, two, four, or six critical bands. Six listeners with normal hearing were tested. The thresholds for the multitone complexes indicate that they generally can be detected even when the level of a single component is a few dB below the threshold. The average detection advantage is consistent with predictions for multiple observations in independent, frequency-selective auditory channels, but differences among listeners are apparent. The loudness matches also vary somewhat among listeners. Five of the six listeners matched tone complexes composed of subthreshold components to a pure tone a few dB above threshold. This indicates that the loudness of tones at or even below threshold is greater than zero for these five listeners. A simple model of loudness summation was used to obtain loudness functions from the individual listeners' loudness matches. The slopes of the loudness functions [log(loudness) plotted as a function of log(intensity)] generally exceed unity at low levels and are near 0.2 at 40 dB SL. This shallow slope at moderate levels agrees with loudness functions derived from data on temporal integration of loudness. The average loudness function derived from the present data also is in good agreement with a variety of previous data obtained by magnitude estimation, magnitude production, ratio production, and measurements of binaural loudness summation.

Adolescent↗

PubMed1998

Temporal integration of loudness under partial masking.

This paper tests the hypothesis that the loudness ratio between equal-SPL tones with different durations is the same at all SPLs. Detection thresholds and levels required to produce equal loudness for 5- and 200-ms tones presented in quiet or in broadband noise were measured using adaptive, two-interval, two-alternative forced-choice procedures. Tone levels ranged from 5 dB SL to 90 dB SPL for the long tones and about 100 dB SPL for the short tones. Results from six listeners with normal hearing show that the amount of temporal integration, defined as the level difference between equally loud 5- and 200-ms tones, varies nonmonotonically with level and is greatest at moderate levels. The average amount of temporal integration in quiet is about 15 dB near threshold, increases to a peak of 27 dB when the 5-ms tone is about 58 dB SPL, and decreases to about 15 dB near 100 dB SPL. For masker levels of 40, 60, and 80 dB SPL, the amount of temporal integration near masked threshold remains near 15 dB. The maximum amount of temporal integration decreases as masker level increases and occurs at progressively higher levels. At high levels, the amount of temporal integration is nearly the same as in the quiet for all masker levels. Loudness functions derived by applying the equal-loudness-ratio hypothesis to the data yield excellent predictions of loudness matches between tones in the quiet and partially masked tones with the 40- and 60-dB maskers. For the 80-dB masker, clear deviations are present. These results support the equal-loudness-ratio hypothesis, but suggest that intense masking may alter the loudness ratio between 200- and 5-ms tones.

Adult↗

PubMed1997

Age of second-language acquisition and perception of speech in noise.

To determine how age of acquisition influences perception of second-language speech, the Speech Perception in Noise (SPIN) test was administered to native Mexican-Spanish-speaking listeners who learned fluent English before age 6 (early bilinguals) or after age 14 (late bilinguals) and monolingual American-English speakers (monolinguals). Results show that the levels of noise at which the speech was intelligible were significantly higher and the benefit from context was significantly greater for monolinguals and early bilinguals than for late bilinguals. These findings indicate that learning a second language at an early age is important for the acquisition of efficient high-level processing of it, at least in the presence of noise.

Adolescent↗

PubMed1997

Temporal integration of loudness, loudness discrimination, and the form of the loudness function.

Temporal integration for loudness of 5-kHz tones was measured as a function of level between 2 and 60 dB SL. Absolute thresholds and levels required to produce equal loudness were measured for 2-, 10-, 50-, and 250-ms tones using adaptive, two-interval, two-alternative forced-choice procedures. The procedure for loudness balances was new and employed ten interleaved tracks to obtain concurrent measurements for ten tone pairs. Each track converged at the level required to make the variable stimulus just louder than the fixed stimulus. Thus, the data yield estimates of the just-noticeable difference (jnd) for loudness level and temporal integration for loudness. Results for four listeners show that the amount of temporal integration, defined as the level difference between equally loud short and long tones, varies markedly with level and is largest at moderate levels. The effect of level increases as the duration of the short stimulus decreases and is largest for comparisons between the 2- and 250-ms tones. The loudness-level jnds are also largest at moderate levels and, contrary to traditional jnds for the level of two equal-duration tones, they do not appear to depend on duration. The latter finding indicates that loudness discrimination between stimuli that differ along multiple dimensions is not the same as level discrimination between stimuli that differ only in level. An equal-loudness-ratio model, which assumes that the ratio of loudnesses for a long and short tone at equal SPL is the same at all SPLs, can explain the level dependence of temporal integration and the loudness jnds. It indicates that the loudness function [log(loudness) versus SPL] is flatter at moderate levels than at low and high levels in agreement with earlier findings for 1-kHz tones [M. Florentine et al., J. Acoust. Soc. Am. 99, 1633-1644 (1996)].

Female↗

PubMed1996

Temporal integration of loudness as a function of level.

Temporal integration of loudness for 1-kHz tones and broadband noises was compared over a wide range of levels. Absolute thresholds and levels required to produce equal loudness were measured for 5-, 30-, and 200-ms stimuli using an adaptive, two-interval, two-alternative forced-choice procedure. Levels ranged from 5 to 80 dB SL for noises and from 5 to 90 dB SL for tones. Results for six listeners with normal hearing show that the amount of temporal integration, defined as the level difference between equally loud 5- and 200-ms stimuli, varies nonmonotonically with level. The average amount of temporal integration varies from about 10-12 dB near threshold, to a peak of 18-19 dB when the 5-ms tone is about 56 dB and the 5-ms noise is about 76 dB SPL; the amount of temporal integration decreases to 10 dB for tones and 13 dB for noises with levels around 100 dB SPL. The data for tones are in good agreement with the majority of existing data. The data for noises are within the range of the few previous data, but the effect of level differs from that obtained in previous studies. The present results indicate that the growth of loudness may, at least in part, be consistent with the nonlinear input/output function of the basilar membrane.

Adult↗

PubMed1996

Stimulus-driven, time-varying weights for comodulation masking release.

This study tests the hypothesis that comodulation masking release (CMR) is mediated by "listening in the valleys" [S. Buus, J. Acoust. Soc. Am. 78, 1958-1965 (1985)]. Detectability was measured for signals consisting of six consecutive 25-ms, 1-kHz tone pulses presented in a 50-Hz-wide masker or in maskers consisting of seven 50-Hz-wide noises, one critical band apart, with either correlated or uncorrelated envelopes. The level of each signal pulse varied randomly around masked threshold according to Gaussian distributions with rms perturbations (standard deviations) of 3 or 6 dB. For each listener and condition, the responses from 5000 trials were sorted to construct conditional psychometric functions for d' as a function of signal-pulse intensity for ten ranges of short-term level of the on-frequency masker band during the pulse. The slopes of these functions for three normal listeners decrease markedly with increasing short-term masker level for the correlated multiband masker, but are largely constant for the other maskers. This indicates that the weight applied to the signal channel is high when the masker level is low and vice versa for the correlated masker, but is approximately constant for single-band and uncorrelated multiband maskers. These findings provide direct evidence that CMR is mediated by "listening in the valleys," but models based on direct envelope comparison may also account for the results if they are modified to include a compressive nonlinearity before the comparison.

Adult↗

PubMed1995

Masked level discrimination: deterring profile listening.

Two experiments examined how level discrimination (also called intensity discrimination) between two successive three-tone complexes depends on the bandwidth and rove range of a notched-noise masker. The three-tone complex consisted of equally intense components at 0.84, 1, and 1.17 kHz set to 25, 55, or 85 dB SPL. The notch extended from 0.77 to 1.27 kHz for all masker bandwidths. The masker level changed randomly on each presentation to reduce profile cues. Results from five listeners showed that level-discrimination thresholds, delta L's (= 20 log([p + delta p]/p), where p is pressure), increased somewhat as the rove range increased. In contrast to profile-discrimination experiments, the delta L's did not decrease with increasing masker bandwidth. In addition, when the rove range was 10 dB or larger, discrimination was generally better than the best possible performance by a profile observer. The results indicate that profile analysis is not essential for reasonably good level discrimination in the presence of notched-noise maskers.

Adolescent↗

PubMed1995

Psychometric functions for level discrimination in cochlearly impaired and normal listeners with equivalent-threshold masking.

The purpose of this study was to determine whether the form of the psychometric functions for level discrimination (also known as intensity discrimination) measured in a two-interval, two-alternative forced-choice paradigm changes with hearing impairment. Measurements of sensitivity, d', as a function of delta L (= 20 log[(p+delta p)lp], where p is pressure) were obtained in six listeners with cochlear impairments, five normal listeners tested in the quiet, and two masked-normal listeners. Stimuli were chosen to encompass a wide range of conditions and difference limens. Results show that the d' is nearly proportional to delta L over the entire range of stimuli. This simple relationship is not changed by cochlear impairments or masking noise. These findings indicate that if the transformation from stimulus intensity to decision variable is affected by hearing impairment or masking, the change affects both the mean and the standard deviation in the same manner--i.e., the standard deviation may be proportional to the derivative of the transformation as was suggested by Zwislocki and Jordan [J. Acoust. Soc. Am. 79, 772-780 (1986)]. The results also lend support to the notion that delta L--plotted on a logarithmic scale--is an appropriate representation of level-discrimination performance.

Adult↗

PubMed1994

Auditory facilitation: procedural or sensory effect?

A few studies have reported that, under certain conditions, thresholds following exposure to a sound may be lower than those measured without prior stimulation. For example, Rubin [J. Acoust. Soc. Am. 32, 670-681 (1960)] found a 7-dB negative shift in threshold, for a 20-ms tone presented 160 ms after termination of a low-level cue tone. This "auditory facilitation" was obtained with an up-and-down psychophysical method. In the present study, auditory facilitation was reexamined using an adaptive, two-interval, two-alternative-forced-choice (2I, 2AFC) procedure. Thresholds were measured for 20-ms tones at 1 and 5 kHz, preceded by a 15-dB SL 80-ms cue tone of the same frequency. In addition, thresholds were measured with the cue absent. The results show that thresholds can be lower in the presence of the cue than in its absence, but the effect averages 0.5 dB or less and seems to be independent of cue-signal delay between 80 and 640 ms. Because this finding contrasts with the 7-dB facilitation, which Rubin obtained using an up-and-down method, part of his experiment was replicated and the results were essentially the same as his. The failure to find a pronounced facilitation effect with a 2I, 2AFC procedure indicates that the poststimulatory lowering of threshold found by Rubin primarily resulted from biases and criterion shifts.

Auditory Perception↗

PubMed1993

Intensity perception. XIV. Intensity discrimination in listeners with sensorineural hearing loss.

Intensity discrimination of pulsed tones (also called level discrimination) was measured as a function of level in 13 listeners with sensorineural hearing impairment of primarily cochlear origin, one listener with a vestibular schwannoma, and six listeners with normal hearing. Measurements were also made in normal ears presented with masking noise spectrally shaped to produce audiograms similar to those of the cochlearly impaired listeners. For unilateral impairments, tests were made at the same frequency in the normal and impaired ears. For bilateral-sloping impairments, tests were made at different frequencies in the same ear. The normal listeners showed results similar to other data in the literature. The listener with a vestibular schwannoma showed greatly reduced intensity resolution, except at a few levels. For listeners with recruiting sensorineural impairments, the results are discussed according to the configuration of the impairment and are compared across configurations at equal SPL, equal SL, and equal loudness level. Listeners with increasing hearing losses at frequencies above the test frequency generally showed impaired resolution, especially at high levels, and less deviation from Weber's law than normal listeners. Listeners with decreasing hearing loss at frequencies above the test frequency showed nearly normal intensity-resolution functions. Whereas these trends are generally present, there are also large differences among individuals. Results obtained from normal listeners who were tested in the presence of masking noise indicate that elevated thresholds and reduced dynamic range account for some, but not all, of the effects of recruiting sensorineural impairment on intensity resolution.

Acoustic Stimulation↗

PubMed1992

Effects of cochlear impairment and equivalent-threshold masking on psychoacoustic tuning curves.

Psychoacoustic tuning curves in simultaneous masking were measured in three groups: listeners with hearing impairment of primarily cochlear origin, normal listeners with equivalent-threshold masking (ETM) and normal listeners tested in the quiet. ETM was produced by presenting a continuous back-ground noise that was spectrally shaped to yield masked thresholds within 3 dB of each impaired listener's quiet thresholds. For the tuning curves, the level of a 50-Hz-wide noise band necessary to mask a 10-dB SL tone was measured for six masker frequencies. Results under ETM indicate that the shape of the tuning curve depends not only on masked threshold at the probe frequency but also on the spectral shape of the masker. Tuning curves are abnormally broad in some impaired listeners even when the effects of their elevated thresholds, audiometric configuration and altered intensity perception are taken into account by comparisons with normal listeners with ETM.

Acoustic Stimulation↗

PubMed1991

Psychometric functions for level discrimination.

To determine the form of psychometric functions for 2I,2AFC level discrimination (commonly called intensity discrimination), ten increment levels were presented in random order within blocks of 100 trials. Stimuli were chosen to encompass a wide range of conditions and difference limens: eight 10-ms tones had frequencies of 0.25, 1, 8, or 14 kHz and levels of 30, 60, or 90 dB SPL; two 500-ms stimuli also were tested: a 1-kHz tone at 90 dB SPL and broadband noise at 63 dB SPL. For each condition, at least 20 blocks were presented in mixed order. Results for five normal listeners show that the sensitivity, d', is nearly proportional to delta L (= 20 log [(p + delta p)/p], where p is sound pressure) over the entire range of difference limens. When d' is plotted against Weber fractions for sound pressure, delta p/p, or intensity, delta I/I, exponents of the best-fitting power functions decrease with increasing difference limens and are less than unity for large difference limens. The approximately proportional relation between d' and delta L agrees with modern multichannel models of level discrimination and with psychometric functions derived for single auditory-nerve fibers. The results also support the notion that the difference limen, expressed as delta LDL and plotted on a logarithmic scale, is an appropriate representation of performance in level-discrimination experiments.

Adult↗

PubMed1990

Hearing conservation programs in Massachusetts' vocational/technical schools.

A survey of vocational/technical schools in Massachusetts was performed to evaluate the prevalence of and need for hearing conservation programs. The surveys were sent to the superintendents or principals of all 27 regional schools in Massachusetts. Surveys consisted of questions in the areas of shop noise exposure, use of safety equipment, and hearing conservation education. Results indicate that (1) many teachers and students may be exposed to hazardous noise levels (2) hearing protection is not required in one-third of the schools and is used less frequently than other safety equipment, and (3) teachers desire additional training in hearing conservation and would welcome the assistance of an audiologist. These results point out the need for obtaining measurements of noise levels in the school shops, designing hearing conservation programs for school settings, implementing mandatory use of hearing protection, and providing education in hearing conservation for students and teachers.

Ear Protective Devices↗

PubMed1990

Temporal integration of trains of tone pulses by normal and by cochlearly impaired listeners.

Two experiments investigated the temporal integration of trains of tone pulses by normal and by cochlearly impaired listeners. In the first experiment, thresholds were measured for a single 5-ms, 4-kHz tone pulse, and for ten such tone pulses as a function of interpulse interval (delta t). For normal listeners, temporal integration, defined as the threshold difference between one and ten pulses, was about 8 dB for delta t less than 20 ms, and about 5 dB at longer delta t's. For impaired listeners, temporal integration was only about 2-3 dB across the range of delta t's (5-160 ms) studied. A second experiment measured psychometric functions (log d' versus log signal power) for a single pulse and for ten pulses with delta t's of 5 ms and 80 ms. The normal listeners' functions had slopes close to unity in all three conditions, with a few exceptions. The impaired listeners' functions had slopes close to unity for ten pulses with delta t = 5 ms, but had slopes significantly greater than unity for delta t = 80 ms, and for a single pulse. At delta t = 80 ms, the increase in d' relative to the condition with a single tone was similar (a factor of square root of 10) for both impaired and normal listeners, but the threshold difference was smaller for the impaired listeners due to their steeper psychometric functions. For impaired listeners, then, temporal integration at delta t = 80 ms was normal in terms of a change in d' but abnormal when measured as a threshold difference.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗