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PubMed1991

A comparison between the electrically reproduced loudness and the original loudness of speech at high levels.

Four words lists of a German Speech Intelligibility Test (DIN 45621) were recorded at 60 and 75 dB SPL. Both recordings were presented to 20 normally hearing subjects at 75 dB SPL via free-field equalized earphones. Discrimination in noise was significantly better in the original recording at 60 dB SPL. The better understanding may be explained by a more favourable consonant-vowel intensity ratio. Moreover, a significant increase in fundamental frequency could be demonstrated at the higher recording level. The implications for speech audiometry and hearing aids are discussed. Furthermore, it was found from loudness comparisons that both recordings were equally loud at a level of 75 dB SPL. However, significantly increased loudness was indicated in the 75 dB SPL recording by the loudness calculation procedure ISO 532 B.

Acoustics↗
PubMed1991

Direction-dependent amplification of the human outer ear.

The transfer function of the outer ear in humans was determined by using the impulse technique. Signals were delivered from 325 or 393 positions on an imaginary sphere surrounding the experimental subject. Changes of sound pressure level in the ear canal show that certain frequency bands are amplified maximally if they impinge onto the ear from certain directions. For some frequency bands there are two directions of sound incidence that cause best amplification in the ear canal. The directionality of the human pinna appears to increase at higher frequencies. The amount of amplification by the outer ear of frequencies between 2 and 15 kHz was also determined by measuring the free-field transfer function.

Ear Canal↗
PubMed1992

Estimation of the loudness of tinnitus from matching tests.

To correct for the influence of recruitment when the loudness of tinnitus is measured by a balance test in an ear with sensorineural hearing loss, an averaged loudness function was devised, which converts the sensation level (SL) of tinnitus into an estimate of the effective loudness level. This is essentially the same as a phon scale except for the difference in reference level, and is defined as the equivalent SL of the tinnitus as if measured in an ear with a bone-conduction threshold of 0 dB HL at a frequency between 500 Hz and 4000 Hz. Using this function, the median estimated loudness of tinnitus from 301 randomly selected patients was 15 dB 'effective loudness level' with a maximum of more than 60 dB. A nomogram was made for clinical use to determine the effective loudness level easily from the SL of tinnitus and the bone-conduction HTL of the test ear. Although somewhat approximate, the effective loudness level is considered to be an unbiased loudness estimate of tinnitus under the condition that only the SL of tinnitus and the bone-conduction HTL are available, and makes it easier to appreciate the actual loudness compared with a complex loudness unit such as on the sone scale.

Adolescent↗
PubMed1994

An experimental evaluation of the effects of transcutaneous nerve stimulation (TNS) and applied relaxation (AR) on hearing ability, tinnitus and dizziness in patients with Menière's disease.

In 20 patients diagnosed with Menière's disease, transcutaneous nerve stimulation (TNS) and applied relaxation (AR) were used as a treatment aimed at reducing tinnitus and dizziness and increasing hearing ability. The main aim of the study was to examine whether TNS could be regarded as a more beneficial treatment regimen than AR. An experimental between-group cross-over design was used. The results from the experimental phase (group comparisons) showed a significantly increased ability to hear for the TNS group when measured on visual analogue scales. During the same period, the AR-group showed a significant hearing improvement for the ear not primarily affected by Menière's disease as measured with pure tone audiometry. The vestibular tests did not reveal any significant changes either after TNS or AR intervention. Tinnitus matching showed changes of pitch and loudness before and after both TNS and AR intervention. However, no statistically significant changes between treatment regimes were found on these measures. The results from this study did not show TNS to be superior to AR in reducing tinnitus, dizziness or increasing hearing ability.

Adult↗
PubMed1996

The relationship between uncomfortable loudness level and maximum power output in subjects recently fitted with NHS hearing aids.

It is generally agreed that the maximum output from a hearing aid should not exceed the subject's uncomfortable loudness level (ULL). However, this relationship is not easily defined as electroacoustic data are usually measured in a 2 cc coupler and auditory measurements are usually obtained from supra-aural transducers calibrated in a 6 cc coupler. The aim of the study was to investigate this relationship in 21 adults who were being fitted with a hearing aid for the first time. A probe-tube microphone system was used to measure the sound pressure level of both variables in the ear canal. The measurement of ULL was determined using the method recommended by the British Society of Audiology (1987). The ULL values were around 110 dB SPL (+/-10) when measured in the ear canal. The maximum output of the hearing aid was obtained by correcting the SSPL90 with the subject's own real ear to coupler difference. The results revealed that the real ear saturation response (RESR) of the newly fitted hearing aid was typically 115-120 dB SPL (+/-8). The RESR exceeded the ULL for 19 (90%) subjects on average at five of the seven frequencies and by 12 dB. While further research is needed to determine whether discomfort occurred in real life situations, the implications are that the subject may use the hearing aid at less than optimum settings to prevent loudness discomfort or may ultimately reject the hearing aid altogether.

Acoustics↗
PubMed1996

Predictors of daily assessed hearing aid use and hearing capability using visual analogue scales.

Following the fitting of hearing aids, 53 patients rated themselves daily during one week on visual analogue scales dealing with aspects of the hearing aids (HA) and hearing capability. Before this, the prescribing audiology assistant categorized the patient into one of four groups depending on whether she thought the patient was going to be successful or not at home after the fitting. Also compared were the effects of type of audiogram, type of hearing aid and monaural or binaural fitting on the self-assessed and audiological variables. Finally, a series of multiple regressions were performed on the data set. The results showed that the audiology assistant could predict some aspects of HA usage, but not hearing capability. Patients rated the BTE and the ITC aids as clearer than the ITE aids, but a wide range of aids were prescribed making conclusions difficult. No clear effects were found for type of audiogram or type of fitting. Multiple regressions showed that clearness of sound in the HA was the most important variable in predicting the results on hearing capability. The use of repeated daily measures is recommended in research on the effects of HA fitting.

Aged↗
PubMed1996

Abnormalities of ICP loudness adaptation at 1000 Hz associated with higher frequency (cochlear) loss.

Individuals with higher frequency hearing loss, when tested at 1000 Hz, showed more loudness adaptation at 40 dB HL and less at 60 dB HL (ISO) than the normal listeners. Adaptation was measured with the monaural method described by Weiler, Sandman and Pederson (1981), now called the Ipsilateral Comparison Paradigm (ICP) by Dange et al. (1993). Using the same method Korman (1986) had shown that a complex combination of stimulus conditions, including intensity, produced differences between a similar group with high frequency hearing loss and normals. The current results confirm the value of this method for studying adnormalities in the loudness function at middle intensities. Because it is a quick and reliable method we believe it has potential for clinical use but acknowledge considerable research and development is necessary.

Aged↗
PubMed1999

Use of a loudness model for hearing aid fitting: II. Hearing aids with multi-channel compression.

A model for predicting loudness for people with cochlear hearing loss was applied to the problem of the initial fitting of a multi-channel compression hearing aid. The fitting was based on two constraints: (1) The specific loudness pattern evoked by speech of a moderate level (65 dB SPL) should be reasonably flat (equal loudness per critical band), and the overall loudness should be similar to that evoked in a normal listener by 65-dB speech (about 23 sones for binaural listening); (2) Speech with an overall level of 45 dB SPL should just be audible in all frequency bands from 500 Hz up to about 4 kHz, provided that this does not require compression ratios exceeding about 3. These two constraints were used to determine initial values for the gain, compression ratio and compression threshold in each channel of a multi-channel compression system. This initial fitting was based entirely on audiometric thresholds; it does not require suprathreshold loudness measures. The fitting method was evaluated using an experimental fast-acting four-channel compression system. The initial fitting was followed by an adaptive procedure to 'fine tune' the fitting, and the aids were then used in everyday life. Performance was evaluated by use of questionnaires and by measures of speech intelligibility. Although the fine tuning resulted in modest changes in the fitting parameters for some subjects, on average the frequency response shapes and compression ratios were similar before and after the fine tuning. The fittings led to satisfactory loudness impressions in everyday life and to high speech intelligibility over a wide range of levels. It was concluded that the initial fitting method gives reasonable starting values for the fine tuning.

Acoustic Stimulation↗
PubMed1999

Use of a loudness model for hearing aid fitting: III. A general method for deriving initial fittings for hearing aids with multi-channel compression.

A model for predicting loudness for people with cochlear hearing loss is applied to the problem of the initial fitting of multi-channel fast-acting compression hearing aids. The fitting is based entirely on the pure tone audiogram, and does not require measures of loudness growth. One constraint is always applied: the specific loudness pattern evoked by speech of a moderate level (65 dB SPL) should be reasonably flat (equal loudness per critical band), and the overall loudness should be similar to that evoked in a normal listener by 65-dB speech. This is achieved using the 'Cambridge' formula. For hearing aids where the compression threshold in each channel can be set to a very low value, an additional constraint is used: speech with an overall level of 45 dB SPL should be audible over its entire dynamic range in all frequency channels from 500 Hz up to about 4 kHz. For hearing aids where the compression thresholds cannot be set to very low values, a different additional constraint is used: the specific loudness pattern evoked by speech of a high level (85 dB SPL, and with the spectral characteristics of shouted speech) should be reasonably flat, and the overall loudness should be similar to that evoked in a normal listener by 85-dB speech. For both cases, compression ratios are limited to values below 3. For each of these two cases, we show how to derive compression ratios and gains, and for the first case, compression thresholds, for each channel. The derivations apply to systems with any number of channels. A computer program implementing the derivations is described. The program also calculates target insertion gains at the centre frequency of each channel for input levels of 50, 65 and 80 dB SPL, and target gains at the eardrum measured relative to the level at the reference microphone of a probe microphone system.

Auditory Threshold↗
PubMed2002

Relationship of intraoperative electrically evoked stapedius reflex thresholds to maximum comfortable loudness levels of children with cochlear implants.

Previous studies of the relationship between the intraoperatively obtained electrically evoked stapedius reflex threshold (ESRT) and the maximum comfortable loudness (MCL) values used to program the speech processor of cochlear implant (CI) patients have indicated that ESRTs provide an inexact estimate of MCL. In order to determine whether this estimate might be more exact for electrodes in different parts of the electrode array, we studied the electrode-specific relationships between ESRT and MCL in 29 Med-E1 Combi 40+ and 25 Nucleus CI 24 M patients after first fitting of the speech processor and 2 and 6 months later. The MCL values were mostly less than the ESRT values, but increased progressively over the first 6 months, reaching 83% and 72% of the ESRT values, on average, across all electrodes for the Med-E1 and Nucleus systems respectively. The population variation across electrodes decreased over the 6-month observation period and was least for the apical half of the array, for which the correlation coefficients of regressions between ESRT and MCL were around 0.65 for both systems. These results indicate that estimates of MCL values from the ERST are more accurate for the apical half of the intra-cochlear array and could then be described by an offset value plus an increase of MCL by 0.62 and 0.53 of ESRT for the Med-E1 and Nucleus systems, respectively.

Adolescent↗
PubMed2005

Examining the validity of numerical ratios in loudness fractionation.

Direct psychophysical scaling procedures presuppose that observers are able to directly relate a numerical value to the sensation magnitude experienced. This assumption is based on fundamental conditions (specified by Luce, 2002), which were evaluated experimentally. The participants' task was to adjust the loudness of a 1-kHz tone so that it reached a certain prespecified fraction of the loudness of a reference tone. The results of the first experiment suggest that the listeners were indeed able to make adjustments on a ratio scale level. It was not possible, however, to interpret the nominal fractions used in the task as "true" scientific numbers. Thus, Stevens's (1956, 1975) fundamental assumption that an observer can directly assess the sensation magnitude a stimulus elicits did not hold. In the second experiment, the possibility of establishing a specific, strictly increasing transformation function that related the overt numerals to the latent mathematical numbers was investigated. The results indicate that this was not possible for the majority of the 7 participants.

Adult↗
PubMed2005

Sweep-induced acceleration in loudness change and the "bias for rising intensities".

A pure tone changing continuously in intensity shows sweep-induced fading (SIF) of loudness as intensity sweeps down and may show a lesser degree of sweep-induced enhancement (SIE) as intensity sweeps up (Canévet & Scharf, 1990); the former effect has been called decruitment, the latter upcruitment. An opposite effect-upsweeps being judged to show more loudness change than downsweeps--has been reported by Neuhoff (1998). These disparate results might stem from several procedural differences. We found that differences in the sweep's duration and intensity level did not account for the disparity, nor did the presence of a steady tone preceding the sweep. In a second experiment, direct judgments of sweep size, such as those Neuhoff's (1998) listeners made, were affected not only by sweep size itself, but also by the intensity at the end of the sweep. The latter effect was especially marked for upsweeps. Neuhoffs (1998) proposed "bias for rising intensities" was found only with a method for judging sweep size that is more sensitive to end level than to sweep size.

Adult↗
PubMed2006

Sequential effects in successive ratio estimation.

Sequential effects are examined in four successive ratio estimation (RE) experiments. The procedure in successive RE is identical to that for magnitude estimation (ME), but the task in successive RE is to estimate the ratio of the current to the previous sensation magnitude, and not the separate magnitudes of the sensations. A positive stimulus context effect was found in successive RE for several continua, in agreement with results previously found for ME. The residual autocorrelation for successive RE was zero in many cases, but in some cases negative autocorrelation was found, which is in contrast to the positive autocorrelation that is typically found for ME and other magnitude scaling procedures. It is shown that, when the role of perceptual error is recognized, negative autocorrelation is predicted by a classical model of ratio estimation. Some aspects of response bias are also discussed.

Humans↗
PubMed2001

Stream segregation of narrow-band noise bursts.

Normally hearing adults heard rapid alternations of a pair of band-limited noise bursts that had flat spectra (in terms of equal-loudness weighting of components) and sharp band edges. The bursts differed in center frequency (CF), but were matched on overall intensity, on bandwidth (BW) on a log frequency scale, and (roughly) on pitch strength. Listeners judged the ease with which the sequence could be held together perceptually in a single auditory stream (vs. forming separate high and low streams). Involuntary segregation was examined as a function of the following measures of frequency separation of the alternating noise bands: (1) the closest band edges, (2) the most remote band edges, (3) the CFs of the bands on a logarithmic scale, and (4) the BWs. Segregation was best predicted from the separation of the two CFs on a log-frequency scale (very strong effect). Increasing the BWs of the two alternating bursts (the same size, in log frequency, for both bands) also led to greater segregation (very weak effect).

Adult↗
PubMed2001

Adaptive threshold estimation with unforced-choice tasks.

This paper evaluates an adaptive staircase procedure for threshold estimation that is suitable for unforced-choice tasks-ones with the additional response alternative don't know. Within the framework of a theory of indecision, evidence is developed that fluctuations of the response criterion are much less detrimental to unforced-choice tasks than to yes/no tasks. An adaptive staircase procedure for unforced-choice tasks is presented. Computer simulations show a slight gain in efficiency if don't know responses are allowed, even if response criteria vary. A behavioral comparison with forced-choice and yes/no procedures shows that the new procedure outdoes the other two with respect to reliability. This is especially true for naive participants. For well-trained participants it is also slightly more efficient than the forced-choice procedure, and it produces a smaller systematic error than the yes/no procedure. Moreover, informal observations suggest that participants are more comfortable with unforced tasks than with forced ones.

Adult↗
PubMed2002

Top-down gain control in the auditory system: evidence from identification and discrimination experiments.

The influence of intensity range in auditory identification and intensity discrimination experiments is well documented and is usually attributed to nonsensory factors. Recent studies, however, have suggested that the stimulus range effect might be sensory in origin. To test this notion, in one set of experiments, we had listeners identify the individual tones in a set. One baseline condition consisted of identifying four 1-kHz, low-intensity tones; the other consisted of identifying four 1-kHz, high-intensity tones. In the experimental conditions, these baseline tone sets were augmented by adding a fifth tone at either 1 or 5 kHz. Added 5-kHz tones had little effect on identification accuracy for the four baseline tones. When an added 1-kHz tone differed substantially in intensity from the four baseline tones, it adversely affected performance, with the addition of a high-intensity tone to a set of low-intensity tones having a more deleterious effect than the addition of a low-intensity tone to a set of high-intensity tones. These and further results, obtained in an exploration of this asymmetrical range effect in a third identification experiment and in two intensity-discrimination experiments, were consistent with the notion of a nonlinear amplifier under top-down control whose functions include protection against sensory overload from loud sounds. The identification data were well described by a signal-detection model using equal-variance Laplace distributions instead of the usual Gaussian distributions.

Adult↗
PubMed2002

Deriving the loudness exponent from categorical judgments.

The power function exponent for loudness is traditionally determined by means of a process of magnitude estimation. It is demonstrated in this paper that the exponent can also be obtained by using the procedure of absolute identification of sound intensity. It has been shown that subjects' responses to tones of a given intensity are distributed in a normal distribution whose variance depends on the range, R, over which the tones are distributed. By means of a standard statistical transformation, the normal density in log space is converted to the corresponding probability density in linear space. The power function exponent can then be obtained directly from the linear probability density. We also suggest that there is a direct relationship between the information calculated from experiments on absolute identification of sound intensity and the neurophysiological, poststimulus histogram measured in a nerve fiber in the auditory nerve.

Humans↗