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Results for “Loudness Perception”

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At least 811 records · Page 45Linked to original sources
PubMed1998

Encoding loudness by electric stimulation of the auditory nerve.

Electric charge has long been hypothesized to be the effective stimulus variable that determines loudness evoked by directly stimulating the auditory nerve. This 'equal-charge, equal-loudness' hypothesis predicts that stimulus amplitude and duration can be traded linearly to produce equal loudness. Loudness sensations from threshold to maximum loudness were measured systematically as a function of stimulus amplitude and duration in cochlear implant listeners. The measured data do not support the equal-charge, equal-loudness hypothesis: an increment in stimulus amplitude produces a significantly louder sensation than the same change in stimulus duration. Instead of the linear equal-charge model, a power-function model successfully predicts the measured data and should be used to encode loudness in electric hearing.

Adult↗
PubMed1998

Anisotropic neural interaction in the primary auditory cortex of guinea pigs with sound stimulation.

Neural interaction in the primary auditory cortex of guinea pigs anesthetized with sodium pentobarbital was studied using a single line multi-electrode (4 x 1) aligned across and along the isofrequency band. Under the spontaneous condition, the neural interaction was isotropic; the amplitude of cross-correlogram peaks decreased as the electrode separation increased both across and along the isofrequency band. Under tone stimulation, the neural interaction was anisotropic; the amplitude of peaks was decreased rapidly beyond 400 microm across the isofrequency band, while it decreased little up to 700 microm along the isofrequency band. This anisotropic interaction was dependent on the stimulus intensity.

Acoustic Stimulation↗
PubMed1999

Psychophysical laws revealed by electric hearing.

Psychophysical laws relate the intensity of a physical stimulus to its perceived magnitude. G.T. Fechner hypothesized 150 years ago that the psychophysical law can be derived by measuring intensity discrimination, but modern scientists favor a direct magnitude estimation approach and are still divided on whether and how intensity discrimination is related to sensation magnitude. This controversy is partially due to the uncertainty of the role of the sensory organ in the psychophysical law. Here we bypass the auditory sensory organ with electric stimulation of the human auditory nerve and find a close coupling between intensity discrimination and loudness functions in electric hearing. Our results support Fechner's hypothesis in principle but not the exact relationship from which he derived his logarithmic law.

Adult↗
PubMed2000

A systematic representation of interaural intensity differences in the auditory cortex of the pallid bat.

The current model of cortical processing of auditory spatial information is based on an orthogonal representation of frequency and binaural response properties, but how this arrangement leads to representation of space in the auditory cortex is unclear. This study describes the first evidence of a cortical substrate for the systematic representation of space in a region of primary auditory cortex of the pallid bat that subserves passive sound localization. The organizational feature of this region is a systematic shift in sensitivity to interaural intensity differences across the cortical surface, suggesting a topographic representation of horizontal space based on the distribution of activity within the neuron population.

Animals↗
PubMed2000

Do perceived loudness cues contribute to duration mismatch negativity (MMN)?

This study explored the contribution of perceived loudness cues to mismatch negativity produced in response to a 125 ms duration deviant tone among a regular sequence of 50 ms standard tones. Each individual was required to adjust the intensity of a 125 ms tone until it matched the perceived loudness of a 50 ms tone. The mismatch negativity produced to the duration deviant presented at the same intensity as the standard was contrasted with that produced to the same deviant at each individual's perceived loudness equivalence. Despite detectable difference perceived loudness (approximately 1.3 dB), adjusting the intensity of the deviant tone did not significantly reduce mismatch negativity amplitude to the duration deviant. Results are discussed with reference to temporal window of integration.

Acoustic Stimulation↗
PubMed2001

Do loudness cues contribute to duration mismatch negativity reduction in schizophrenia?

The present study explored duration mismatch negativity (MMN) reduction in schizophrenia. Duration MMN studies usually employ tones of very short duration (< 200 ms). For stimuli < 200 ms in duration, an increment in duration is accompanied by an increase in perceived loudness. It was previously proposed that the effectiveness of duration MMN in revealing MMN reduction in schizophrenia might be explained by patients being insensitive to loudness cues and duration increments. In this study we equated loudness cues in a typical duration MMN paradigm and explored the effect of this manipulation on MMN amplitude reduction in schizophrenia. The manipulation had little effect on a healthy comparison group but had a marked effect on the MMN generated in the patient group who produced a significantly smaller MMN response to the regular duration deviant than to that in the equated loudness condition. This result was interpreted as demonstrating that patients exhibit a very marked insensitivity to duration increments.

Acoustic Stimulation↗
PubMedDate not supplied

The effect of signal type on the loudness discomfort level.

Loudness discomfort levels (LDL's) were obtained on 19 normal-hearing subjects with 18 different stimuli using a simple up-down adaptive procedure. The stimuli included five pure tones, five one-third octave bands of noise, five one-third octave bands of filtered multi-talker babble, wide-band noise, spondaic words, and sentences. Results indicated there was no significant difference among the three frequency-specific stimuli. However, a significant frequency effect was found. LDL's for the two speech stimuli and wide-band noise were not significantly different and were similar to values for signals in the 500 to 4000 Hz region. Although differences among mean LDL's for the various signals were quite small, large intrasubject variability among the signal types and across frequency was observed. This fact would seem to preclude the conclusion that equivalent LDL's would be obtained on an individual regardless of the type of stimulus.

Acoustic Stimulation↗
PubMedDate not supplied

Loudness discomfort levels of hearing-impaired listeners using speech material.

This study was undertaken to: (1) investigate the effects of speech materials on the loudness discomfort level (LDL); (2) assess the intrasession stability among three LDL trials; and (3) examine the relationships between the speech LDL and the pure-tone and spondee thresholds. Ninety-six adults with mild-to-moderate sensorineural hearing loss were tested. Findings showed little or no difference among five commercially available speech materials. Thus, it was concluded that differences in speech materials do not comprise a major source of variability among studies when comparing mean LDL data. Group means may, however, obscure significant individual variations in LDL's that result from differing speech materials. Considerable LDL variability among listeners with similar thresholds was found, suggesting an intolerably high error rate for predictive purposes.

Auditory Threshold↗
PubMedDate not supplied

Comparison of three hearing aid prescription procedures.

The gain recommendations for twenty-five hearing aid condidates with sensorineural hearing loss were determined by direct measurement of most comfortable loudness level and by two different formulas which were based on air-conduction thresholds for 500, 1000, 2000, and 4000 Hz. At 500 Hz, one formula recommended significantly less gain than did the other two procedures. At the other frequencies, there were no systematic, clinically significant mean differences among the three methods. However, the direct measurement of most comfortable loudness level resulted in markedly greater variability in gains as a function of hearing level than did the two formula methods. This variability suggested that wherever possible, gain should be determined by most comfortable loudness level measurement rather than by prediction from pure-tone threshold.

Adult↗
PubMedDate not supplied

Effects of a competing message on the speech comfortable loudness level for two instructional sets.

The effects of a competing message on the speech comfortable loudness level (CLL) was compared for two instructional sets in 2 conditions of quiet and in the presence of a four-talker babble competing message. Kopra and Blosser's (24) instructions were selected to sample the middle of the CLL range, whereas Lucker et al.'s (27) instructions sampled the upper limit of the CLL range. Two groups of 12 normal-hearing subjects were tested using a method of adjustment. The results indicated no significant differences between the initial and final CLL's in quiet. However, data for each instructional set showed that the CLL's obtained with Lucker et al.'s phraseology (97.8 dB SPL) was significantly higher than with Kopra and Blosser's instructions (75.2 dB SPL). The four-talker babble served to raise the CLL, although less effect was observed on the upper limit of the CLL range than for the middle portion of this range. The clinical implications of these findings are discussed.

Acoustic Stimulation↗
PubMedDate not supplied

Comparison of hearing threshold level and most comfortable loudness level in hearing aid prescription.

In three experiments, the predictability of the hearing aid gain actually used by clients was compared with that predicted by using data based upon hearing threshold level and data based upon most comfortable loudness level. At the frequencies tested, the mean difference between the predicted and obtained gain was smaller when based upon prediction from the hearing threshold level. It is concluded that from the standpoint of predicting user's gain, the hearing threshold level provides greater accuracy than does most comfortable loudness level.

Auditory Threshold↗
PubMedDate not supplied

Prediction of aided preferred listening levels for hearing aid gain prescription.

Relative accuracy was assessed for two methods for predicting preferred listening levels as estimated by measurements of the upper limit of the comfortable loudness range (ULCL). Sixteen hearing-impaired subjects provided ULCL data for eight test stimuli on each of five occasions. The stimuli were four narrow bands of noise centered at 500, 1000, 2000, and 4000 Hz and four narrow bands of speech babble also centered at 500, 1000, 2000, and 4000 Hz. Best estimates of ULCL were determined to be the means of the five measurements for each subject for each of the eight test signals. Results revealed that the mean ULCL for each speech-band stimulus was predicted more accurately from that subject's first measurement of ULCL for that speech-band than from his/her threshold for the same signal. However, the accuracy with which noise-band ULCLs could be used to predict the mean speech-band ULCL varied with frequency and with the number of trials averaged. Relationship of ULCL to preferred listening levels was explored by comparing results obtained in this study with work of previous investigators. Implications of the results for hearing aid gain prescription are discussed.

Acoustic Stimulation↗
PubMedDate not supplied

Relationship between the calibration tone and speech volume unit (VU) levels for some commercially available test tapes.

The relationship between the calibration tone and speech volume unit (VU) levels for nine commercially recorded speech tests was studied. Two procedures were used. In procedure 1, experienced clinicians reported observations of four different audiometer VU meters responding to six commercially available speech tests. Differences in magnitude estimates among judges were usually about 1 dB or less. Peak VU level deviations from the zeroed calibration tone were within +/- 1.5 VU except for the Fulton Lewis Jr. recording, which varied by about -4.8 VU. In procedure 2, a video system was used to recorded precisely VU meter responses to clinical speech materials. Differences between the calibration tones and speech levels were similar to those obtained using multiple observers. Statistically significant (p less than or equal to 0.01) differences were found between the speech levels of the commercial test recordings.

Audiometry↗
PubMedDate not supplied

Effect of a pretest listening exposure on the ascending-descending gap at most comfortable loudness levels.

The effect of approach mode (ascending versus descending, A-D) on comfortable loudness was determined for a 1000 Hz pure tone using Békésy audiometry. Two groups (experimental and control) of 10 normal-hearing young adult subjects measured their most comfortable loudness (MCL) levels pre- and post-treatment. The experimental group received a treatment of a listening exposure to a 70 dB intensity range before the test. The results demonstrated a statistically significant change of the A-D gap in the experimental group while the A-D gap for the control group remained essentially unchanged. It is proposed that MCL is underestimated in the ascending approach and overestimated on the descending testing, which results in the A-D gap. In addition, the results demonstrate the importance of the procedures used in research and clinic of the MCL.

Acoustic Stimulation↗
PubMedDate not supplied

Relationship between aided preferred listening level and long-term listening range.

The long-term listening range was defined as extending, at any frequency, from the threshold of audibility to the upper limit of the comfortable loudness range. The relationship between the aided preferred listening level and the long-term listening range was investigated by analyzing data obtained from 16 hearing impaired subjects. Results support a tentative conclusion that the aided preferred listening level is equal to the midpoint of the long-term listening range. Application of this relationship to the specification of frequency/gain function is discussed.

Adult↗
PubMedDate not supplied

Evaluation of the minimal auditory capabilities (MAC) test in prelingual and postlingual hearing-impaired adults.

The Minimal Auditory Capabilities (MAC) battery was used to evaluate the auditory performance of nine postlingual and ten prelingual adults with severe to profound hearing loss. Results suggest that degree of hearing loss overrides relative language skills as the primary factor affecting performance. The MAC battery appears promising as a tool for evaluating and monitoring both prelingual and postlingual adults using conventional hearing aids or cochlear implants.

Adolescent↗
PubMedDate not supplied

Telephone listening ability for hearing-impaired individuals.

Forty-five subjects with bilateral sensorineural hearing losses were divided into three groups (N = 15/group) based on the audiometric configuration of their test ear. The subjects were evaluated in three listening conditions by assessing their word discrimination ability by presenting stimuli at 86 dB SPL (simulating the output of a standard telephone handset ) and most comfortable loudness (MCL) (simulating the output of a telephone amplifier handset ). The three listening conditions were TDH-39 earphone, unaided telephone, and aided telephone with their personal hearing aid acoustically coupled to a telephone handset . Results indicated that subjects with precipitous hearing losses had similar word discrimination scores for all three listening conditions at 86 dB SPL and MCL. Subjects with gradual slope or flat hearing losses had similar word discrimination scores with a TDH-39 earphone, unaided telephone, and their hearing aids acoustically coupled to a telephone handset at 86 dB SPL. The subjects with gradual slope or flat losses also had similar word discrimination scores across the listening modes at MCL, but they had better word discrimination scores in all listening modes when the word lists were presented at MCL compared with 86 dB SPL.

Hearing Aids↗
PubMedDate not supplied

The relationship of continuous (C) and interrupted (I) tones at threshold and most comfortable loudness (MCL) in hearing-impaired ears.

Differences in the Bekesy tracking levels of continuous (C) and interrupted (I) tones at both threshold and most comfortable loudness (MCL) were determined in a large clinical sample of persons with hearing loss. Results indicate small but significant C-I differences not only at the two levels separately but also in the tracking of C and I tones at threshold relative to MCL, regardless of frequency or hearing loss severity. Such results may have implications for both diagnostic and rehabilitative audiology.

Adult↗