Assessing growth of loudness in children by cross-modality matching

This study examined the clinical feasibility, validity, and reliability of loudness growth assessment using cross-modality matching (CMM) between line length and loudness in 16 children 4 to 12 years old with normal hearing or bilateral sensorineural hearing losses ranging from moderate to severe in degree. Eight adult listeners with normal hearing were used as a comparison group. Loudness growth functions and real-ear measures were obtained for 500-Hz and 2,000-Hz narrowband noise stimuli for each individual. No significant differences were found between the loudness slope values for the adults and children with normal hearing. Loudness growth functions of the children with sensorineural hearing loss were significantly steeper (larger) than the slopes obtained from children with normal hearing. The numeric slope value of the loudness growth function became larger and more variable as children's hearing threshold increased and differed for children with similar thresholds. The loudness functions obtained for retested participants at two different test sessions were highly correlated. Real-ear measurements revealed that for equivalent input stimulus levels, significantly higher stimulus levels were present in the ear canals of children versus adults. Although adults and children with normal hearing had similar overall rates of loudness growth, discrete points along the loudness growth function were judged to be louder by the children. This preliminary study suggests that measures of loudness growth using CMM between line length and loudness are feasible, valid, and reliable in children with normal hearing or sensorineural hearing loss. The individual variability noted in slope values for children with hearing loss attests to the importance of subjective assessments of loudness. The protocol used in this study may have potential as a clinical tool for selecting and fitting amplification technology for children with hearing loss as young as 6 years.     

Aided loudness growth and satisfaction with everyday loudness perception in compression hearing aid users

The primary goal of this study was to examine the relationship between listeners' loudness growth and their satisfaction with loudness when wearing wide-dynamic-range compression (WDRC) hearing aids. An absolute-magnitude-estimate procedure was used to obtain listeners' unaided and aided loudness growth functions in response to a 500 and 2000 Hz warble tone. In general, listeners' unaided loudness growth functions were steeper than the average normal-hearing listeners' functions for both frequencies, and their aided loudness growth functions were shallower than their unaided functions. Loudness growth functions tended to be undercompressed for 500 Hz but overcompressed for 2000 Hz. The Profile of Aided Loudness (PAL) questionnaire was administered to determine listeners' loudness satisfaction in everyday listening situations. Most listeners were satisfied with their perception of soft, average, and loud environmental sounds, regardless of how well or not well their WDRC aids normalized their aided loudness growth.     

Cross-modality matching: a tool for measuring loudness in sensorineural impairment.

OBJECTIVE: The main goal of this study was to establish the viability of cross-modality matching (CMM) for the measurement of individual loudness functions in sensorineural-impaired hearing. To achieve this goal, CMM was tested rigorously to assess four measurement requirements: 1) internal consistency; 2) small relative variance across listeners; 3) test-retest reliability; and 4) data validity. DESIGN: The measurements involved two sensory continua: perceived length and loudness. Sensation-magnitude functions were generated for all listeners from absolute magnitude estimation (AME) of perceived length, from CMM between loudness and perceived length, and from AME and absolute magnitude production (AMP) of loudness. A total of 211 listeners, 83 with normal hearing at the stimulus frequency and 128 with a diagnosis of cochlear impairment of long duration, performed all four magnitude-scaling tasks. Supplementary loudness matches also were obtained. RESULTS: Based on the analysis of data, the following results were obtained. First, in accord with loudness measures in normal hearing, loudness measures in cochlear-impaired hearing showed that individuals with bilateral impairments can produce internally consistent loudness data. Second, over the stimulus range where cochlear impairment steepens the loudness function, in a log-log plot loudness slopes derived from CMM, like those obtained from AME and AMP of loudness, were larger in cochlear-impaired hearing than in normal hearing. However, the results of CMM were typically less variable than those obtained from AME and AMP of loudness, permitting a clear-cut distinction between loudness growth rates (slopes) in normal and cochlear-impaired hearing. Third, the results showed that within a cochlear-impaired population, much of the intersubject variability of the slope of the loudness function can be ascribed to the heterogeneity of individual thresholds. Consistent with loudness matching, the size of the slopes increased with the degree of hearing loss. The dependence of the size of the slopes on the degree of hearing loss was observed for hearing losses as large as 75 dB. Fourth, test-retest reliability data for 36 listeners showed that CMM can yield reliable and stable loudness-growth measures in cochlear-impaired hearing over the long term. Finally, equal-sensation matches obtained directly from loudness matching closely agreed with those obtained indirectly from magnitude scaling, indicating that CMM is a valid method for the measurement of loudness magnitudes. CONCLUSIONS: Taken together, the results demonstrate that CMM can yield stable, accurate, and robust loudness growth measures in cochlear-impaired hearing. Given its apparent reliability, validity, and ease of application, CMM has the potential to become a powerful tool for assessing the growth of loudness in a clinical population. Loudness-level functions derived from CMM may well be important for determining the frequency-gain response of a hearing aid that most closely compensates for the distorted input-output function of the impaired auditory system.     

Effect of hearing loss, centre frequency, and bandwidth on the shape of loudness functions in categorical loudness scaling.

Loudness functions of narrow-band and broad-band stimuli were measured with eight normally-hearing and eight hearing-impaired listeners using a categorical loudness scaling method. In the normally-hearing listeners, narrow-band stimuli, generally generated loudness functions whose slope increased with increasing level, whereas broad-band stimuli generated more linear loudness functions. These differences can be explained by the level dependence of spectral loudness summation, which is known to be most prominent at moderate levels. In the hearing-impaired listeners, the narrow-band loudness functions generally showed a more linear shape than in the normally-hearing listeners. A consequence of these findings might be that the optimal shape of the input/output curve of a hearing aid is affected not only by the signal power in the respective frequency channels but also by the bandwidth of the input signal. However, there were considerable differences between listeners in both groups regarding the individual shape and absolute position of the loudness functions. Therefore, no normative reference could be extracted that would allow for a quantification of the bandwidth effect on an individual basis.     

Effect of frequency content on categorical loudness normalization

In this study, increases in loudness with increases in bandwidth, termed loudness summation, were derived from loudness growth functions estimated using a loudness-scaling procedure. The results revealed that at equal loudness category, categorical loudness summation was generally larger in normal-hearing than in hearing-impaired subjects; furthermore, the increase in loudness summation at intermediate loudness levels observed in the former, was absent in the latter. These results, in broad agreement with recent data from the literature, can be explained in the light of physiological data on cochlear compression. One implication of these results regarding hearing aid fitting was that channel-by-channel loudness normalization was effective only when the incoming sound was closed in bandwidth to one of the test stimuli.     

Fitting range of the BAHA Cordelle

The performance of the most powerful Bone-Anchored Hearing Aid (BAHA) currently available, the BAHA Cordelle, was evaluated in 25 patients with severe to profound mixed hearing loss. Patients showed bone conduction thresholds at 500, 1000 and 2000 Hz, ranged between 30 and 70 dB HL, and an additional air-bone gap of about at least 30 dB. With the BAHA Cordelle, free-field thresholds improve relative to bone-conduction thresholds with 1.5, 5.0, 17.8, and 4.3 dB at 500, 1000, 2000, and 4000 Hz, respectively, with substantial inter-individual variability. The differences in unaided air conduction thresholds and aided free-field thresholds amount to 45.3, 45.8, 47.5, and 43.5 dB at 500, 1000, 2000, and 4000 Hz, respectively. Speech perception, measured both with monosyllables of the consonant-vowel-consonant type and with bisyllables, showed highly similar results. The fitting range of a (linear) hearing aid is determined by its gain characteristics. Requiring aided speech reception thresholds at or better than 65 dB SPL results in an upper limit of the fitting range of the BAHA Cordelle for bone-conduction thresholds of 51, 56, 67, and 58 dB HL at 500, 1000, 2000, and 4000 Hz, respectively. The dynamic range provided by the BAHA Cordelle was estimated from loudness growth functions at 500, 1500, and 3000 Hz employing 7-point categorical scaling. On average, aided loudness growth functions exhibit normal slopes but they level off at input levels of about 80, 70, 65 dB SPL for 500, 1500, and 3000 Hz stimuli, respectively. Measurements with a skull simulator demonstrated that the levelling-off reflects saturation of the output of the Cordelle. The relatively low saturation levels of the device suggest that increasing maximum output levels may be a worthwhile consideration for candidates with more profound sensorineural loss.     

Fitting hearing aids using clinical measures of loudness discomfort levels: an evidence-based review of effectiveness

Clinical measurement of the loudness discomfort level (LDL) historically has been part of the hearing aid fitting procedure, and this clinical practice remains popular today. LDL measurements also are recommended in contemporary hearing aid fitting protocols. Yet, surveys show that many hearing aid users are dissatisfied with the loudness of their hearing aids. In this evidence-based review article, we evaluate the effectiveness of clinical LDL measurements. Specifically, we asked the question "Are the clinical measurements of LDL for adult patients predictive of aided acceptance and satisfaction of loudness for high inputs in the real world?" Nearly 200 articles were reviewed; three met the criteria set forth in this review. The evidence supported using unaided LDLs for selecting the maximum real-ear output of hearing aids. No study using aided LDLs or aided loudness verification met the criteria. The level of the evidence for the three articles using unaided LDLs was low; no higher than Level 4. The limited number of studies, the level of evidence, and the statistical power of the studies prevents us from making a strong recommendation concerning the clinical use of LDL measures. Additional research in this area, especially research employing randomized controlled trials would be a useful addition to this body of literature.     

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.     

Revisiting loudness measures in children using a computer method of cross-modality matching (CMM)

The test efficiency and reliability of loudness assessment using a computer-controlled method of cross-modality matching (CMM) between line length and loudness was investigated in children 4 to 12 years with normal hearing or mild to severe degrees of sensorineural hearing loss. Adult listeners with normal hearing served as a comparison group. Computer-generated visual and acoustic stimuli were used to derive individual loudness data. Children and adults with normal hearing presented with similar loudness functions, while children with sensorineural hearing loss had steeper functions than their normal-hearing counterparts. Retest data supported reliability of the CMM method with children within the current study and between previous studies performed with a similar, but manual, method. The computer CMM approach proved more time efficient than the manual one, halving the test time. The CMM loudness task in a computerized version may have potential in a research or clinical setting, in particular for individualizing hearing aid fittings with children.     

Variability of most comfortable and uncomfortable loudness levels to speech stimuli in the hearing impaired

Methods for determining hearing aid settings often incorporate measurements of most comfortable loudness (MCL) and uncomfortable loudness (UCL) levels. This study examined the variability of loudness measures and their correlation to threshold data, using speech stimuli presented to hearing-impaired subjects. MCLs, UCLs, speech reception, and speech detection thresholds were obtained from 50 subjects having sensorineural impairments. The stimuli were CID W-2 spondees spoken by three female clinicians. Three MCLs and UCLs were obtained within each session, using ascending runs and a closed-set response list. Fifteen subjects were retested twice over intervals ranging from a week to several months. Between-session variability for the loudness measurements was less than or equal to 10 dB across sessions and speakers for the majority of subjects, with a tendency for the MCL and UCL to increase slightly over time. Significant variability was attributed to the use of live-voice presentation by different clinicians. High positive correlation was found between threshold and loudness data for subjects with relatively flat audiometric configurations but not for subjects demonstrating sharply sloping hearing losses.     

Fitting range of the BAHA Cordelle

The performance of the most powerful Bone-Anchored Hearing Aid (BAHA) currently available, the BAHA Cordelle, was evaluated in 25 patients with severe to profound mixed hearing loss. Patients showed bone conduction thresholds at 500, 1000 and 2000 Hz, ranged between 30?and 70 dB HL, and an additional air-bone gap of about at least 30?dB. With the BAHA Cordelle, free-field thresholds improve relative to bone-conduction thresholds with 1.5, 5.0, 17.8, and 4.3 dB at 500, 1000, 2000, and 4000 Hz, respectively, with substantial inter-individual variability. The differences in unaided air conduction thresholds and aided free-field thresholds amount to 45.3, 45.8, 47.5, and 43.5 dB at 500, 1000, 2000, and 4000 Hz, respectively. Speech perception, measured both with monosyllables of the consonant-vowel-consonant type and with bisyllables, showed highly similar results. The fitting range of a (linear) hearing aid is determined by its gain characteristics. Requiring aided speech reception thresholds at or better than 65 dB SPL results in an upper limit of the fitting range of the BAHA Cordelle for bone-conduction thresholds of 51, 56, 67, and 58 dB HL at 500, 1000, 2000, and 4000 Hz, respectively. The dynamic range provided by the BAHA Cordelle was estimated from loudness growth functions at 500, 1500, and 3000 Hz employing 7-point categorical scaling. On average, aided loudness growth functions exhibit normal slopes but they level off at input levels of about 80, 70, 65 dB SPL for 500, 1500, and 3000 Hz stimuli, respectively. Measurements with a skull simulator demonstrated that the levelling-off reflects saturation of the output of the Cordelle. The relatively low saturation levels of the device suggest that increasing maximum output levels may be a worthwhile consideration for candidates with more profound sensorineural loss.     

Untersuchungen zur Hörflächenskalierung im Rahmen der Hörgeräteversorgung

The loudness perception of patients with hearing aids was measured with a one-stage category loudness scaling procedure. Data were obtained from 102 ears and were studied primarily in older patients who represented the majority of patients with hearing disorders evaluated in our department. In all, 75% of the patients were older than 45 years and had a mean age of 58 years. The reduction of dynamics at high frequencies was considered to be typical for age-related hearing disorders and was easily quantified with loudness scaling. Findings demonstrated that prediction of recruitment was not possible from pure-tone thresholds or even together with uncomfortable loudness levels, since the slopes of the level-loudness functions revealed a high interindividual variability. In contrast, the desired compression ratio can be easily calculated with data from the loudness scaling. In this study the loudness perception of patients with mainly non-linear hearing aids fitted with customary procedures was evaluated. The benefit from the hearing aids was proven with the outcome from the loudness scaling, with testing also allowing for a better fitting of the aids.     

Loudness and auditory steady-state responses in normal-hearing subjects

This study evaluated the use of multiple auditory steady-state responses (ASSRs) to estimate the growth of loudness in listeners with normal hearing. Individual intensity functions were obtained from measures of loudness growth using the contour test and from the electrophysiological amplitude measures of multiple amplitude-modulated (77–105Hz) tones (500, 1000, 2000, and 4000Hz) simultaneously presented to both ears and recorded over the scalp. Slope analyses for the behavioural and electrophysiological intensity functions were separately performed. Response amplitudes of the ASSRs and loudness sensation judgements increase as the stimulus intensity increases for the four frequencies studied. A significant relationship was obtained between loudness and the ASSRs. The results of this study suggest that the amplitude of the ASSRs may be used to estimate loudness growth at least for individuals with normal hearing.     

Loudness and auditory steady-state responses in normal-hearing subjects

This study evaluated the use of multiple auditory steady-state responses (ASSRs) to estimate the growth of loudness in listeners with normal hearing. Individual intensity functions were obtained from measures of loudness growth using the contour test and from the electrophysiological amplitude measures of multiple amplitude-modulated (77-105 Hz) tones (500, 1000, 2000, and 4000 Hz) simultaneously presented to both ears and recorded over the scalp. Slope analyses for the behavioural and electrophysiological intensity functions were separately performed. Response amplitudes of the ASSRs and loudness sensation judgements increase as the stimulus intensity increases for the four frequencies studied. A significant relationship was obtained between loudness and the ASSRs. The results of this study suggest that the amplitude of the ASSRs may be used to estimate loudness growth at least for individuals with normal hearing.     

Use of a loudness model for hearing aid fitting. IV. Fitting hearing aids with multi-channel compression so as to restore 'normal' loudness for speech at different levels

Many researchers have proposed that multi-channel compression hearing aids should process sounds so as to restore loudness perception to 'normal'. However, procedures for achieving this have generally been based on measurements or calculations using narrowband stimuli, and these procedures may not be accurate for broadband sounds such as speech. Here, a model for predicting loudness for people with cochlear hearing loss is used to calculate the frequency- and level-dependent gains that would be required to restore loudness perception to 'normal' for speech-like signals. The calculations are based entirely on the pure tone audiogram, and do not require measures of loudness growth. The model was applied to several different hypothetical hearing losses, varying in slope and severity. In each case, the model was used to calculate the insertion gains (IGs) that would be required as a function of frequency so that speech-shaped noise with a level of 65 dB SPL would evoke a specific loudness pattern matching that for a normal ear. A similar procedure was applied using speech-shaped noise with a level of 85 dB SPL (with the spectral characteristics of shouted speech). The results were used to derive functions relating the required IG to hearing loss for each audiometric frequency and each speech-shaped noise level. These functions were used in turn to derive compression ratios and gains for each channel of a multi-channel compression system. The derivations apply to systems with any number of channels. The outcome is a method than can be used for the initial fitting of multichannel compression hearing aids, so as to restore loudness perception to near 'normal' for broadband speech-like signals.     

An efficient, adaptive method of measuring loudness growth functions

This paper presents a new categorical loudness scaling procedure that differs from previously published loudness scaling procedures by (i) adaptively selecting a new set of levels for each new sequence, (ii) deriving levels that are equispaced on the loudness scale, and (iii) using a continuous scale with few labels. A major advantage of the adaptive procedure is that the individual dynamic range need not be measured prior to loudness testing. The adaptive procedure proved to be time efficient and to produce complete loudness functions from Not heard to Uncomfortably loud for normal hearing and hearing impaired subjects. The pattern of short-term and long-term reliability was similar to that reported for non-adaptive loudness scaling procedures. Three presentations produced a stable loudness function. Normative curves for one octave babble-noise at six test frequencies are presented and compared to normative data obtained with a selection of published categorical scaling procedures.     

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.     

Hearing aid saturation and aided loudness discomfort.

Clinical measurements of the loudness discomfort level (LDL) are generally performed while the subject listens to a particular stimulus presented from an audiometer through headphones (AUD-HP). The assumption in clinical practice has been that the sound pressure level (SPL) corresponding to the sensation of loudness discomfort under AUD-HP conditions will be the same as the corresponding to LDL with the hearing aid. This assumption ignores the fact that the distortion produced by a saturating hearing aid could have an influence on the sensation of loudness. To examine these issues, 5 hearing-impaired subjects were each fit with four linear hearing aids, each having a different saturation sound pressure level (SSPL90). Probe-tube microphone measurements of ear canal SPL at LDL were made while the subjects listened to continuous discourse in quiet under aided and AUD-HP conditions. Also using continuous discourse, real-ear coherence measures were made at various output sound pressure levels near LDL. All four hearing aid types produced mean LDLs that were lower than those obtained under AUD-HP conditions. Those hearing aids with higher SSPL90 produced significantly higher LDLs than hearing aids with lower SSPL90. A significant negative correlation was found between real-ear SPL and real-ear coherence. Quality judgments made at LDL indicated that sound quality of hearing aids with higher SSPL90 was preferred to that of hearing aids with lower SSPL90. Possible fitting implications regarding the setting of SSPL90 from AUD-HP LDL measures are discussed.     

Temporal loudness integration and spectral loudness summation in normal-hearing and hearing-impaired listeners.

The aim of this study was to test for differences between normal-hearing and hearing-impaired listeners regarding two fundamental aspects of intensity perception: loudness integration and loudness summation. Loudness functions for three different stimuli were measured using categorical loudness scaling in 8 normal-hearing and 12 hearing-impaired subjects. The results indicated that temporal loudness integration, defined as the difference in SPL between 16.25-ms and 300-ms noise bursts of equal loudness, was larger in the hearing-impaired than in the normal-hearing listeners. Loudness summation, defined as the difference in SPL between a 300-ms, 1,600-Hz tone pip and a white noise burst of the same duration and loudness, did not differ between the two groups. Implications of these results for hearing aid fitting strategies based on loudness normalization are discussed.