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One of the surprises from analysis of results of an objective and subjective study of British concert halls (1988 Acustica 66,1-14) was that the subjective judgement of loudness in concert halls is influenced not only by sound lev...
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One of the surprises from analysis of results of an objective and subjective study of British concert halls (1988 Acustica 66,1-14) was that the subjective judgement of loudness in concert halls is influenced not only by sound level but also by the source-receiver distance. This response implies that the same sound level is judged louder at positions further from the orchestra platform. Whereas level decreases with distance in actual halls, loudness is judged more-or-less independent of position in average halls (except at positions close to the platform and seats overhung by balconies). As an observation it ties in with evidence from experimental psychologists for loudness constancy throughout a space. The sound strength C is the sound level in an auditorium normalised to the sound power level of the source; the traditional criterion of acceptability for level is that G≥0 dB. The paper proposes that, on the basis of subjective evidence and objective behaviour in auditoria, the criterion for G should not be a unique value of G but rather a function of source-receiver distance.
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Objective: This study investigates the effect of spectral loudness summation (SLS) in the electrical domain as perceived by cochlear implant (CI) users. Analogous to SLS in the acoustical domain, SLS was defined as the effect of e...
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Objective: This study investigates the effect of spectral loudness summation (SLS) in the electrical domain as perceived by cochlear implant (CI) users. Analogous to SLS in the acoustical domain, SLS was defined as the effect of electrode separation at a fixed overall stimulation rate. Design: Categorical loudness scaling (CLS) was conducted at three overall stimulation rates using single-electrode stimuli and multi-electrode stimuli presented interleaved on two or four electrodes. The specific loudness of the pulses in the multi-electrode stimuli were equalized based on single-electrode measurements at the same overall stimulation rate. At a fixed overall stimulation rate and a fixed loudness perception, SLS was calculated as the difference in mean current between single-electrode and multi-electrode stimuli. Study sample: Ten postlingually deafened adult CI users. Results: The amount of SLS varied between subjects and between the number and location of the stimulated electrodes in the multi-electrode configuration. SLS was significantly higher than 0 for a subset of the subjects. Conclusions: For a subpopulation of CI users, loudness models should account for nonlinear interactions between electrodes (in the perceptual domain). Similarly, SLS should be accounted for when using CLS outcomes for fitting purposes, at least in a subpopulation of CI users.
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Loudness functions and binaural loudness summation was investigated in acoustically stimulated bilaterally implanted cochlear implant users. The study was aimed at evaluating growth of loudness functions and binaural loudness summ...
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Loudness functions and binaural loudness summation was investigated in acoustically stimulated bilaterally implanted cochlear implant users. The study was aimed at evaluating growth of loudness functions and binaural loudness summation in cochlear implant subjects as a function of stimulus presentation level at different frequencies. Loudness was assessed using a rating procedure on a scale of 0 to 100. Three experimental conditions were tested: monaural right, monaural left and binaural, each with bands of noise with center frequencies of 0.25, 1, and 4 kHz. Fifteen implanted and five normal-hearing subjects (control group) participated in the experiments. Results demonstrated large variability in the slopes of the loudness functions and the presence of loudness summation in bilateral cochlear implant users, with large individual differences among subjects.
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Objective: In categorical loudness scaling (CLS), subjects rate the perceived loudness on a categorical scale with alternatives. ISO 16832 describes an internationally standardized CLS procedure for the acoustical domain. This stu...
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Objective: In categorical loudness scaling (CLS), subjects rate the perceived loudness on a categorical scale with alternatives. ISO 16832 describes an internationally standardized CLS procedure for the acoustical domain. This study focuses on the reproducibility of CLS following the recommendations of ISO 16832 using electrical stimuli presented to cochlear implant (CI) users. Design: Repeated CLS measurements were done using single-electrode stimuli at four electrode positions. Loudness growth functions (LGFs) described loudness as a function of level (mu A). LGF shapes were characterized with an exponential b parameter. The reproducibility of the b parameter and inter-session intra-subject differences in percentage dynamic range (DR) between 'Very Soft' and 'Loud - Very Loud' levels were analysed. Study sample: Ten CI users. Results: Inter-session differences did not significantly differ between loudness categories or electrode positions. Across loudness categories the standard deviation of inter-session differences equalled 7.2% DR. The reproducibility of LGF shapes was moderate (r = 0.63). The LGFs of 43% of the measured electrodes significantly deviated from linear (nonzero b parameter). Conclusions: The reproducibility was comparable to the reproducibility for acoustical stimulation in normal-hearing and hearing-impaired listeners. CLS data for electrical stimuli are preferably fitted with a model that is flexible in describing LGF shapes.
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Previously it has been found through a series of psychoacoustical experiments that the arithmetic average of sound pressure level calculated in octave bands is a good estimator of loudness for various kinds of environmental noise....
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Previously it has been found through a series of psychoacoustical experiments that the arithmetic average of sound pressure level calculated in octave bands is a good estimator of loudness for various kinds of environmental noise. Remarkably, the arithmetic average of sound pressure level in octave bands from 63 Hz to 4 kHz, L_(m,1/1)(63-4k), strongly correlates with the loudness level specified in ISO 532B, LL(Z), as well as with loudness assessment. To investigate this relationship further, a numerical study has been carried out based on Zwicker's loudness model. As a result, practical expressions to estimate the loudness levels of general environmental noises from the sound pressure levels in octave bands from 63 Hz or 125 Hz to 4 kHz are proposed.
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Level differences at equal loudness were measured for bandpass noises centered at 1.5 kHz with bandwidths from 5 to 405 Hz and a 1.5-kHz pure tone. Irrespective of the reference (tone or 135-Hz wide noise), the data indicate a dec...
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Level differences at equal loudness were measured for bandpass noises centered at 1.5 kHz with bandwidths from 5 to 405 Hz and a 1.5-kHz pure tone. Irrespective of the reference (tone or 135-Hz wide noise), the data indicate a decrease in loudness with increasing bandwidth. This is at odds with the assumption of stationary loudness models that loudness for sounds with a subcritical bandwidth is determined by the intensity and center frequency only. It is also not in agreement with dynamic loudness models, which predict higher levels for a tone than for equally loud noises, i.e., the opposite effect.
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Objective: Current hearing aid prescription rules assume that spectral loudness summation decreases with hearing impairment and that binaural loudness summation is independent of hearing loss and signal bandwidth. Previous studies...
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Objective: Current hearing aid prescription rules assume that spectral loudness summation decreases with hearing impairment and that binaural loudness summation is independent of hearing loss and signal bandwidth. Previous studies have shown that these assumptions might be incorrect. Spectral loudness summation was measured and compared for loudness scaling and loudness matching. Design: In this study, the effect of bandwidth on binaural summation was investigated by comparing loudness perception of low-pass filtered, high-pass filtered, and broadband pink noise at 35 Categorical Units for both unilateral and bilateral presentation. Study sample: Sixteen hearing-impaired listeners. Results: The results show that loudness differences between the three signals are different for bilateral presentation than for unilateral presentation. In specific, binaural loudness summation is larger for the low-pass filtered pink noise than for the high-pass filtered pink noise. Finally, individual variability in loudness perception near loudness discomfort level was found to be very large. Conclusions: Loudness matching is offered as a fast and reliable method to measure individual loudness perception. As discomfort with loud sounds is one of the major problems encountered by hearing aid users, measurement of individual loudness perception could improve hearing aid fitting substantially.
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Recent advancement in digital hearing aids has the flexibility to restore the lost compressive nonlinearity of cochlea by compression circuits. The current study is aimed at studying the loudness growth functions in normal hearing...
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Recent advancement in digital hearing aids has the flexibility to restore the lost compressive nonlinearity of cochlea by compression circuits. The current study is aimed at studying the loudness growth functions in normal hearing and hearing impaired adults those who use compressionhearing aids. Categorical loudness scaling was assessed in both the normal hearing and hearing impaired adults with hearing aid. There frequencies were tested viz. 500 Hz, 1000 Hz and 2000 Hz. The hearing aid programme was held constant (NAL-NL1) across participants. The results revealed asignificant main effect of group on loudness growth function; where the loudness growth grew steeper for low to moderately intense sounds in hearing impaired than for normal hearers. This implies, the differences in loudness growth function persist in hearing impaired even after fitting withan appropriate compression hearing aids.
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The loudness of a tone can be reduced by preceding it with a more intense tone. This effect, known as induced loudness reduction (ILR), has been reported to last for several seconds. The underlying neural mechanisms are unknown. O...
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The loudness of a tone can be reduced by preceding it with a more intense tone. This effect, known as induced loudness reduction (ILR), has been reported to last for several seconds. The underlying neural mechanisms are unknown. One possible contributor to the effect involves changes in cochlear gain via the medial olivocochlear (MOC) efferents. Since cochlear implants (CIs) bypass the cochlea, investigating whether and how CI users experience ILR should help provide a better understanding of the underlying mechanisms. In the present study, ILR was examined in both normal-hearing listeners and CI users by examining the effects of an intense precursor (50 or 500 ms) on the loudness of a 50-ms target, as judged by comparing it to a spectrally remote 50-ms comparison sound. The interstimulus interval (ISI) between the precursor and the target was varied between 10 and 1000 ms to estimate the time course of ILR. In general, the patterns of results from the CI users were similar to those found in the normal-hearing listeners. However, in the short-precursor short-ISI condition, an enhancement in the loudness of target was observed in CI subjects that was not present in the normal-hearing listeners, consistent with the effects of an additional attenuation present in the normal-hearing listeners but not in the CI users. The results suggest that the MOC may play a role but that it is not the only source of these loudness context effects.
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In the presence of background noise, the perceptual loudness of speech signal significantly decreases, resulting in the deterioration of intelligibility and clarity. In this letter, we propose a novel approach to enhance the perce...
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In the presence of background noise, the perceptual loudness of speech signal significantly decreases, resulting in the deterioration of intelligibility and clarity. In this letter, we propose a novel approach to enhance the perceived quality of the speech signal when the additive noise cannot be directly controlled. Instead of controlling the background noise, we propose to reinforce the speech signal so that it can be heard more clearly in noisy environments. To find a suitable reinforcement rule, the loudness perception model proposed by Moore is adopted. Experimental results show that the loudness of the reinforced signal can be maintained at the level almost the same as that of the original noise-free speech, and the proposed algorithm can enhance the perceived speech quality under various noise environments.
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