Biomedical subjects

Mary Florentine

Publications and source records attributed to Mary Florentine.

14 recordsLinked to original sources

PubMed2006

Reaction time to 1- and 4-kHz tones as a function of sensation level in listeners with normal hearing.

OBJECTIVE: Measures of reaction time (RT) near threshold have been used to indicate whether listeners with hearing losses of primarily cochlear origin experience greater loudness at elevated thresholds than at normal thresholds. These measurements have been based on the assumption that RTs near threshold are not affected by stimulus frequency in the 1- to 4-kHz range. The present study tests this hypothesis. DESIGN: To gain an understanding of how RT is affected by frequency, RTs to 1- and 4-kHz tones were measured in 16 listeners with normal hearing across a wide range of sensation levels (SLs). RESULTS: Statistical analyses indicate that RTs are affected by frequency in some listeners. This effect is most common at low SLs but is also present at higher SLs. Learning effects could not account for the observed differences between RTs at the two frequencies. CONCLUSIONS: Although reaction time-especially at low levels-is affected by stimulus frequency in some listeners, the effect is not large enough to account for the differences in RTs measured in all listeners with impaired hearing in other studies.

Acoustic Stimulation↗

PubMed2006

Effect of masker-fringe onset asynchrony on overshoot (L).

The study examines how overshoot is influenced by masker-signal onset asynchrony when the masker contains frequencies above or below the signal frequency. Masked thresholds were measured for a 2-ms tone at 5 kHz. The measurements were made in a reference condition with a narrow center-band (CB) noise masker (4590-5464 Hz), and in conditions with either a low-fringe (1900-4590 Hz) or a high-fringe noise band (5500-11 000 Hz) added to the CB. The signal always came on 2 ms after the onset of the CB. The time interval, between fringe and signal onsets varied from -98 ms (signal onset before fringe onset) to +502 ms (signal onset after fringe onset). Results show that overshoot is largest, 8-11 dB, for a high fringe with onset occurring between 8 ms before the signal onset and 12 ms after it. Thus, pronounced overshoot is observed even when the high fringe is gated on after the signal's offset. Low fringes produce no more than 4 dB of overshoot, much less than high fringes produce. The finding of pronounced overshoot elicited by a high fringe presented shortly after the end of the signal suggests that overshoot is governed, at least in part, by central mechanisms.

Acoustic Stimulation↗

PubMed2006

Loudness of brief tones measured by magnitude estimation and loudness matching.

McFadden [J. Acoust. Soc. Am. 57, 702-704 (1975)] questioned the accuracy and reliability of magnitude estimation for measuring loudness of tones that vary both in duration and level, whereas Stevens and Hall [Percept. Psychophys. 1, 319-327 (1966)] reported reasonable group data. To gain insight into this discrepancy, the present study compares loudness measures for 5- and 200-ms tones using magnitude estimation and equal-loudness matches from the same listeners. Results indicate that both procedures provide rapid and accurate assessments of group loudness functions for brief tones, but may not be reliable enough to reveal specific characteristics of loudness in individual listeners.

Acoustic Stimulation↗

PubMed2006

Monaural and binaural loudness of 5- and 200-ms tones in normal and impaired hearing.

The difference in level required to match monaural and binaural loudness of 5- and 200-ms tones was measured for listeners with normal and impaired hearing. Stimuli were 1-kHz tones presented at levels ranging from 10 to 90 dB sensation level. Sixteen listeners (eight normal and eight with losses of primarily cochlear origin) made loudness matches between equal-duration monaural and binaural tones using an adaptive 2AFC procedure. The present results corroborate existing data for 200-ms tones in normal listeners and provide new data for 5-ms tones. On average, the binaural level difference required for equal loudness of monaural and binaural tones is about the same for 5- and 200-ms tones of equal level and changes as a function of level. The group data for normal and impaired listeners are in reasonable agreement with data in the literature. However, the data from some of the impaired listeners deviate markedly from the average, indicating that group data do not accurately represent the behavior of all impaired listeners. Derived loudness functions from the loudness-matching data are reasonably consistent with individual data in the literature.

Acoustic Stimulation↗

PubMed2006

Effect of adaptive psychophysical procedure on loudness matches.

Large variability in equal-loudness matches has been observed across studies. The purpose of the present study was to gain insight into the extent to which this variability results from differences in psychophysical procedures and/or differences among listeners. Four adaptive two-interval, two-alternatives-forced-choice procedures were used to obtain equal-loudness matches between 5- and 200-ms 1-kHz tones as a function of level for each of six normal listeners. The procedures differed primarily in the sequence in which the stimuli were presented. The variations tested were the ordering of stimuli by amplitude across blocks of trials (both increasing and decreasing amplitudes), randomizing the order across those blocks, and randomizing the order within blocks. The random-within-block procedure, which sought to randomize any intertrial information, yielded a significantly greater amount of temporal integration than the other three procedures. The results show significant differences in temporal integration measurements at moderate levels for the same listeners across different procedures. Therefore, although there are individual differences among listeners in the amount of temporal integration measured across paradigms, the choice of paradigm also affects the amount of temporal integration measured at moderate levels.

Acoustic Stimulation↗

PubMed2006

A test of the binaural equal-loudness-ratio hypothesis for tones.

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)].

Acoustics↗

PubMed2005

Inferring basilar-membrane motion from tone-burst otoacoustic emissions and psychoacoustic measurements.

The amplitude of otoacoustic emissions, which arise on the basilar membrane, is assumed to be proportional to basilar-membrane motion. It should then be possible to assess basilar-membrane motion on the basis of otoacoustic emissions. The present study provides support for this possibility by comparing basilar-membrane motion inferred from emissions to that inferred from psychoacoustic measures. Three psychoacoustic measurements believed to be associated with basilar-membrane motion were investigated: (1) pulsation threshold; (2) loudness functions derived from temporal integration; and (3) loudness functions derived from loudness matches between pure tones and multitone complexes. Results of the psychoacoustic measurements and of the tone-burst otoacoustic emissions led to very similar estimations of basilar-membrane motion. Accordingly, emissions could serve as an excellent tool--one that is objective, noninvasive, and rapid--for estimating relative basilar-membrane motion.

Acoustic Stimulation↗

PubMed2005

A test of the equal-loudness-ratio hypothesis using cross-modality matching functions.

This study tests the Equal-Loudness-Ratio hypothesis [Florentine et al., J. Acoust. Soc. Am. 99, 1633-1644 (1996)], which states that the loudness ratio between equal-SPL long and short tones is independent of SPL. The amount of temporal integration (i.e., the level difference between equally loud short and long sounds) is maximal at moderate levels. Therefore, the Equal-Loudness-Ratio hypothesis predicts that the loudness function is shallower at moderate levels than at low and high levels. Equal-loudness matches and cross-modality string-length matches were used to assess the form of the loudness function for 5 and 200 ms tones at 1 kHz and the loudness ratio between them. Results from nine normal listeners show that (1) the amount of temporal integration is largest at moderate levels, in agreement with previous studies, and (2) the loudness functions are shallowest at moderate levels. For eight of the nine listeners, the loudness ratio between the 200 and 5 ms tones is approximately constant, except at low levels where it tends to increase. The average data show good agreement between the two methods, but discrepancies are apparent for some individuals. These findings support the Equal-Loudness-Ratio hypothesis, except at low levels.

Acoustic Stimulation↗

PubMed2004

The effects of window delay, delinearization, and frequency on tone-burst otoacoustic emission input/output measurements.

Tone-burst otoacoustic emissions (TBOAEs) are a potential tool for objectively examining cochlear activity in humans. However, their use requires knowledge of how the TBOAE input/output depends on measurement and analysis paradigms. The present experiment examined the effect of variations in response-window timing, response delinearization, and local changes in stimulus frequency on TBOAE input/output measurement. None of these experimental manipulations had a profound effect on TBOAE measurements as long as reasonable parameter choices were made. Nonetheless, judicial choice of the experimental parameters can optimize the assessment of BM I/O functions. It is concluded that the consistency of TBOAE I/O across the parameters tested makes it a viable tool to consider for examining human cochlear activity.

Acoustic Stimulation↗

PubMed2004

Spectral loudness summation and simple reaction time.

The present study evaluates the relation between loudness and simple reaction time (RT). Loudness matches between a narrowband noise (125 Hz wide) and a broadband noise (1500 Hz) were made at levels from near threshold to near 100 dB SPL. Over a similarly wide range of levels, RT to each of the noise bands was also measured. As reported often in previous loudness-matching studies, loudness summation depended strongly on level. With increasing SPL, the level difference between the noises needed to keep them equally loud first increased, to around 10 dB at moderate levels, and then decreased. Except for one listener, the RT data show the same pattern. The level difference needed to keep RT to the two noises the same first increased and then decreased. These results show that RT is closely related to loudness, but not to sensation level. If RT depended on sensation level, the level difference between the two noises needed to achieve equal RT would not change with SPL because the difference in sensation level between two sounds is a constant. Overall, the average results provide strong support for the contention that simple RT and loudness are closely related.

Adult↗

PubMed2003

Perceptual weights in auditory level discrimination.

Perceptual weights in level discrimination (also called intensity discrimination) were determined for 3-, 7-, 15-, and 24-component tone complexes with flat spectral envelopes using a correlational paradigm. Each frequency component was randomly and independently perturbed in level oneach presentation. For the target interval, frequency-component levels were additionally increased by the level increment to be detected, deltaL [= 201og10((p + deltap)/p), where p is pressure]. Weights were calculated from the across-trial correlation between the level perturbations for each frequency component and the interval chosen by the listener. Two conditions were investigated: (1) deltaL was equal across frequency components, and (2) deltaL increased progressively across frequency components. For both conditions, data for four listeners usually showed the greatest weight for the highest frequency component. The two-to-four highest frequency components generally were most important for level discrimination. The effect of increasing deltaL progressively with frequency was small and inconsistent. Additional measurements showed that flanking noise maskers designed to mask spread of excitation caused only small and generally unsystematic changes to the weights. Overall, these results indicate that listeners combine information across a wide range of auditory channels to arrive at a decision for level discrimination, but the weighting of channels appears to be suboptimal.

Adult↗

PubMed2003

A comparison of psychophysical procedures for level-discrimination thresholds.

Five different psychophysical procedures were used to measure level-discrimination (also called intensity discrimination) thresholds for 1-kHz tones at two levels (30 and 90 dB SPL) and two durations (10 and 500 ms). The procedures were the classic transformed up-down staircase method with a two-alternative forced-choice (2AFC) paradigm (UPD), 15- and 50-trial implementations of the method of maximum likelihood (MML) with a cued yes-no paradigm, and 18-trial implementations of ZEST using both cued yes-no and 2AFC paradigms. Results obtained from nine normal listeners show that estimates of level-discrimination thresholds for the four conditions are similar across all five procedures when different points of convergence are accounted for. The variance of threshold estimates within listener and condition was smallest for UPD, largest for the MML with 15 trials, and statistically indistinguishable among the others. The sweat factors ranged from 5.5 for MML with 50 trials to about 1.4 for UPD and ZEST. Simulations show that ideal performance of procedures may be far from real-life experience and that these deviations are likely to depend on complex interactions between listener behavior and parameter choices used for implementing the procedures. Therefore, empirical verification is important for judging the effectiveness of psychophysical procedures.

Adolescent↗

PubMed2003

Interactions between test- and inducer-tone durations in induced loudness reduction.

A tone usually declines in loudness when preceded by a more intense inducer tone. This phenomenon is called "loudness recalibration" or "induced loudness reduction" (ILR). The present study investigates how ILR depends on level, loudness, and duration. A 2AFC procedure was used to obtain loudness matches between 2500-Hz comparison tones and 500-Hz test tones at 60 and 70 dB SPL, presented with and without preceding 500-Hz inducer tones. For 200-ms test and comparison tones, the amount of ILR did not depend on inducer level (set at 80 dB SPL and above), but ILR was greater with 200- than with 5-ms inducers, even when both were equally loud. For 5-ms tones, ILR was as great with 5- as with 200-ms inducers and about as great as when test and inducer tones both lasted 200 ms. These results suggest that (1) neither the loudness nor the SPL of the inducer alone governs ILR, and (2) inducer duration must equal or exceed test-tone duration to yield maximal amounts of ILR. Further analysis indicates that the efferent system may be partly responsible for ILR of 200-ms test tones, but is unlikely to account for ILR of 5-ms tones.

Adult↗

PubMed2002

Growth of loudness in listeners with cochlear hearing losses: recruitment reconsidered.

This article examines how loudness grows with increasing intensity near threshold in five listeners with hearing losses of predominantly cochlear origin. It provides evidence against the pervasive and long-held notion that such listeners show abnormally rapid loudness growth near their elevated thresholds. As in a previous study for listeners with normal hearing, loudness functions near threshold were derived from loudness matches between a pure tone and four- or ten-tone complexes using a simple model of loudness summation. This study assumed that the loudness function had the same form for any component of a complex, but a scale factor that depended on the amount of hearing loss allowed the loudness at threshold to vary with frequency. The best-fitting loudness functions had low-level local exponents [i.e., slopes of the low-level loudness function plotted as log(loudness) versus log(intensity)] that were within the normal range. At 0 dB SL, the average local exponents were 1.26 for the listeners with hearing losses compared with 1.31 for normal listeners, which indicates that loudness near threshold grows at similar rates in normal listeners and listeners with hearing losses. The model also indicated that, on average, the loudness at threshold doubled for every 16 dB of hearing loss. The increased loudness at threshold, together with somewhat enlarged local exponents around 20 dB SL, accounts for the near-normal loudness often obtained for high-SPL tones in listeners with hearing losses. Such loudness functions are consistent with the steep functions shown by classical data on loudness matches between tones for which thresholds are normal and tones for which thresholds are elevated. Thus, the present data indicate that an abnormally large loudness at an elevated threshold is likely to be a better definition of recruitment than the classical definition of it as an abnormally rapid growth of loudness above an elevated threshold.

Adult↗