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.     

改良Contour试验测试正常听力与感音神经性听力损失儿童响度增长

目的 应用改良Contour试验测试听力正常与感音神经性听力损失儿童的响度增长,探讨改良Contour试验的临床应用价值.方法 对26例(26耳)听力正常儿童、25例(25耳)感音神经性听力损失儿童采用临床对照试验用改良Contour试验进行响度测试.在初测2～3周后进行复测.采用多因素方差分析进行统计学分析.结果 在听力正常组、不同程度听力损失组间(F=1386.32,P值＜0.001)及不同响度分级间(F=682.21,P＜0.001)响度的差异均有统计学意义.听力正常组与听力损失组动态范围间差异有统计学意义(F=214.26,P＜0.001).感音神经性听力损失儿童响度增长特征:听力损失越重,响度增长越快,动态范围越小.听力正常组与听力损失组初复测结果高度相关(r值分别为0.97和0.91),可信度较高.结论 儿童助听器验配应尽可能获取个体的响度测试结果以帮助助听器调试到最适合该患儿使用.改良Contour试验易为儿童接受、可靠性好,值得进一步研究用于临床,以帮助提高助听器验配质量.     

Detecting the recruitment phenomenon in adults using 80-Hz auditory steady-state response

ObjectivesThe ASSR is used widely as an objective measurement of hearing in clinical settings because of its high frequency specificity. The recruitment phenomenon is generally detected using subjective evaluations which require direct communication with the patient. If the recruitment phenomenon can be detected with ASSR, it would facilitate diagnosis in patients with developmental disorders and infants.Subjects and methodsWe examined 2 groups of subjects: 10 subjects with unilateral hearing impairment in whom the recruitment phenomenon was detected by the alternate binaural loudness balance test and 12 normal subjects. We compared the relationships between the ASSR response and the stimulus sound pressure level in the 2 groups using the 80-Hz ASSR.ResultsThe amplitude of ASSR was significantly higher in the impaired ear in hearing-impaired subjects compared to a normal ear in normal subjects. The latency of ASSR was significantly shorter in the impaired ear in hearing-impaired subjects than in the normal ear in the normal subjects.ConclusionThis study showed that the recruitment phenomenon caused the higher amplitude and the shorter latency observed in hearing-impaired subjects in the 80-Hz auditory steady-state response (ASSR) in comparison with normal subjects.     

The relationship between the acoustic reflex threshold and levels of loudness categories in hearing-impaired listeners

When applied as a tool for hearing aid fitting, categorical loudness scaling (CLS) is time consuming and not feasible in all subjects. It is therefore desirable to use objective measures for accurate prediction of loudness categories among hearing-impaired individuals. The present study aimed at exploring whether loudness perception at the ART is constant with varying hearing threshold. Seventy-five subjects with various degrees of hearing impairment, measurable acoustic reflex and normal middle ear function participated. The HTLs, ARTs and the levels of six loudness categories at frequencies 0.5, 1, 2 and 4 kHz were determined for all subjects. Loudness at the ART was found to be correlated with the amount of hearing loss. On the basis of these results, it is concluded that the ART cannot be used for accurate estimation of loudness in hearing-impaired subjects.     

伴有重振听力障碍者的助听器验配

目的探讨伴有重振的听力障碍者助听器验配方法。方法对于伴有重振的听力障碍者在选配助听器时尽可能选择压缩线路的数字助听器,或者是具备自动增益功能的助听器;在助听器的调节时应注重最大声输出的限制,并适当降低听觉动态范围较窄的个别频率的增益;此外助听器的适应性训练和随诊调节助听器也是验配成功的重要环节。结果92%的患者获得了满意的配戴效果。结论伴有重振的听力障碍者验配助听器要采用适当的方法。     

Effect of signal duration on categorical loudness scaling in normal and in hearing-impaired listeners.

The present study sought to determine whether the duration of white-noise bursts affects their loudness category rating in the same way for hearing-impaired as for normally-hearing subjects. Twelve normally-hearing and 12 hearing-impaired subjects took part. Categorical loudness growth functions were obtained for 16.25 ms, 32.5 ms, 75 ms, 150 ms and 300 ms white noise bursts. Temporal integration of loudness was defined as the intensity difference needed for stimuli of different durations to result in identical category ratings. In normally-hearing subjects, temporal integration of loudness occurred mainly with the short-duration (16.25 ms and 32.5 ms) stimuli, whereas it was found with almost every stimulus duration in hearing-impaired subjects. In other words, temporal integration of loudness between 16.25 ms and 300 ms stimulus duration was greater in hearing-impaired listeners and there was a difference between normal and hearing-impaired subjects regarding change in loudness perception with stimulus duration. Consequently, the use of fixed-duration stimuli hinders loudness normalization.     

Preferred overall loudness. II: Listening through hearing aids in field and laboratory tests

In a laboratory study, we found that normal-hearing and hearing-impaired listeners preferred less than normal overall calculated loudness (according to a loudness model of Moore & Glasberg, 1997). The current study verified those results using a research hearing aid. Fifteen hearing-impaired and eight normal-hearing participants used the hearing aid in the field and adjusted a volume control to give preferred loudness. The hearing aid logged the preferred volume control setting and the calculated loudness at that setting. The hearing-impaired participants preferred, in median, loudness levels of -14 phon re normal for input levels from 50 to 89 dB SPL. The normal-hearing participants preferred close to normal overall loudness. In subsequent laboratory tests, using the same hearing aid, both hearing-impaired and normal-hearing listeners preferred less than normal overall calculated loudness, and larger reductions for higher input levels In summary, the hearing-impaired listeners preferred less than normal overall calculated loudness, whereas the results for the normal-hearing listeners were inconclusive.     

Language development in hearing-impaired children. Establishment of a reference material for a 'Language test for hearing-impaired children', LATHIC

OBJECTIVE: In Sweden, there has previously been no normalised test material for the evaluation of language development in individual hearing-impaired children, and for the assessment of various methods of auditory habilitation. The purpose of the present study was to compose, apply and evaluate a test for language development in hearing-impaired children, and to establish the first set of reference values related to age, sex, type and degree of hearing impairment. METHODS: A test consisting of nine subtests was assembled and developed for, and subsequently applied to, hearing-impaired children in the age range 4-6 years. The inclusion criteria were a pure tone average of 80 dBHL or less and oral language (Swedish) as the first language. Two hundred and eleven hearing-impaired children and 87 normal hearing control children were tested. RESULTS: The results show that: (1) children with hearing impairment-also unilateral-have a delayed language development; (2) the delay is greater in children with larger losses and tends to decrease with increasing age; (3) 6-year-olds with hearing loss greater than 60 dB have not reached the level of the control group; (4) no difference between right- or left sided deafness with respect to language development was observed; (5) a reference material, applicable during clinical assessment, was established for the most common types of hearing impairment. CONCLUSIONS: The test designed gave graded measures of important aspects of language development in hearing-impaired children. The results merit further application of the test material.     

Assessment of auditory nonlinearity for listeners with different hearing losses using temporal masking and categorical loudness scaling

A dysfunction or loss of outer hair cells (OHC) and inner hair cells (IHC), assumed to be present in sensorineural hearing-impaired listeners, affects the processing of sound both at and above the listeners' hearing threshold. A loss of OHC may be responsible for a reduction of cochlear gain, apparent in the input/output function of the basilar membrane and steeper-than-normal growth of loudness with level (recruitment). IHC loss is typically assumed to cause a level-independent loss of sensitivity. In the current study, parameters reflecting individual auditory processing were estimated using two psychoacoustic measurement techniques. Hearing loss presumably attributable to IHC damage and low-level (cochlear) gain were estimated using temporal masking curves (TMC). Hearing loss attributable to OHC (HL(OHC)) was estimated using adaptive categorical loudness scaling (ACALOS) and by fitting a loudness model to measured loudness functions. In a group of listeners with thresholds ranging from normal to mild-to-moderately impaired, the loss in low-level gain derived from TMC was found to be equivalent with HL(OHC) estimates inferred from ACALOS. Furthermore, HL(OHC) estimates obtained using both measurement techniques were highly consistent. Overall, the two methods provide consistent measures of auditory nonlinearity in individual listeners, with ACALOS offering better time efficiency.     

A method for relating loudness-matching and intensity-discrimination data

A method that allows direct comparisons between pure-tone loudness-matching and intensity-discrimination data in normal and hearing-impaired listeners is described. This method makes a minimal number of assumptions about the relations between loudness perception and intensity-discrimination performance. Loudness is considered to be related to overall, perceived stimulus magnitude and intensity-discrimination performance is considered to reflect the accuracy with which a loudness judgment can be made. Because pure-tone intensity-discrimination performance varies as a function of stimulus level in normal ears, the standard level required to produce a particular difference limen in an impaired ear can be inferred from normal-ear intensity-discrimination data. Thus, plotting standard levels yielding normal difference limens as a function of standard levels yielding the equivalent sized difference limens from a threshold-shifted ear produces a function directly comparable to loudness recruitment functions. If loudness-growth and intensity-difference limens were tightly coupled in threshold-shifted ears, then stimuli that yield equal size difference limens would be equally loud. This relation was tested by obtaining loudness-matching and intensity-discrimination data from normal-hearing listeners with thresholds shifted by a wideband noise and hearing-impaired listeners with cochlear-type hearing losses. The results from these listeners show similarities between the traditional loudness-recruitment functions and "intensity-recruitment" functions derived from the assumed relation between the two measures. The primary difference between the functions is at low and moderate sensation levels where loudness grows at a more rapid rate than the difference limen.     

Detection of loudness recruitment in patients with retrocochlear lesions using the "Würzburger Hörfeld" loudness scaling

BACKGROUND: The pathogenesis of hearing loss caused by cerebellopontine angle tumors such as acoustic neuromas is unknown. The lack of loudness recruitment is thought to be one of the features of retrocochlear hearing impairment. In contrast to conventional suprathreshold tests, the categorial loudness scaling using the "Würzburger H?rfeld" is a valuable tool to describe the individual perception of sound. The aim of the present study was to analyze the loudness growth rate in patients with acoustic neuroma. PATIENTS AND METHOD: Pure tone and speech audiometry as well as auditory brainstem response and bilateral categorial loudness scaling were performed preoperatively in 54 patients with acoustic neuroma. Loudness scaling was done in free field switching off the contralateral ear by using an ear-plug. RESULTS: An abnormal rapid loudness growth function was found in 38 of the 54 patients (70.4%) at least at one frequency on the tumor side. The contralateral side was effected only in 57.4% of the patients. The incidence of a recruitment depended on the frequency with a maximum at 4 kHz. The slope of the loudness function showed a tendency to increase with increasing hearing loss. CONCLUSIONS: Loudness recruitment is not a rare phenomenon in patients with acoustic neuroma. The underlying cause (a preexisting hair cell damage, hair cell changes resulting from an obstruction of the cochlear blood supply or a disruption of the cochlear efferents) still remains unclear.     

响度梯度训练法矫治听障儿童响度低下障碍的个案研究

目的本研究探讨响度梯度训练法在临床上对响度过低患者的康复效果。方法以1名存在响度低下问题的听力障碍儿童为对象，运用响度梯度训练法对其进行提高响度的康复训练，比较分析训练前后该儿童的平均言语强度、强度标准差、最高强度和最低强度。结果响度训练前后患儿平均言语强度存在显著性差异，最低强度无显著差异，最高强度有显著变化。结论响度梯度训练法对听障儿童响度低下问题有康复效果。     

3～4岁听障儿童与健听儿童句子记忆测试结果比较

目的：探讨3～4岁经康复训练的听障儿童与健听儿童通过听觉记忆句子能力的差异。方法选取24例3～4岁经康复训练的听障儿童及14例同龄健听儿童,听障儿童再按助听时间1～2年（10例）和2～3年（14例）分为两组,以言语听觉反应评估（evaluation of auditory response to speech,EARS）中封闭式句子测试的两组图片分别对各组儿童进行测试,比较听障及健听儿童通过听觉完整记忆句子的正确率及平均次数。结果在记忆两组测试句的正确率方面,助听时间2～3年听障儿童第一组测试句的正确率是57．14％,与健听儿童的正确率（58．93％）接近,助听时间1～2年听障儿童的语句的正确率仅为32．5％,低于其他两组儿童;助听时间2～3年听障儿童第二组测试句的正确率是44．64％,高于助听时间1～2年听障儿童的正确率（22．5％）,健听儿童的语句的正确率为55．36％,高于听障儿童组。健听、助听2～3年和助听1～2年听障儿童正确记忆第一组测试句的平均次数分别为2．36±1．08、2．29±1．68、1．30±1．25次,三组间差异无统计学意义（P＞0．05）,但是在第二组测试句测试中,助听1～2年的听障儿童正确记忆句子的次数（0．90±0．57次）明显低于健听儿童（2．21±0．89次）（P＜0．01）和助听2～3年听障儿童组（1．79±1．89次）（P＜0．05）,而助听2～3年的听障儿童组与健听儿童组之间差异无统计学意义（P＞0．05）。结论本组3～4岁听障儿童通过听觉正确记忆句子的能力随着助听时间的延长而提高,并逐渐接近同龄健听儿童,这一能力也受到测试内容的影响。     

The loudness of tinnitus

Although tinnitus causes considerable suffering to many patients, its loudness is small in most cases. Traditionally the loudness is measured with a binaural loudness balance procedure. It is stated that when there is recruitment in the ear to which the test tone is presented, the intensity of the test tone is smaller than its loudness. Therefore in the case of recruitment in the ear to which the test tone is presented, the loudness of tinnitus will be underestimated. In this study the loudness in a group with recruitment in the ear to which the test tone was presented was compared with the loudness in a group with a normal ear to which the test tone was presented. The present results show that although recruitment does have a certain effect, it is very small.     

Loudness perception is influenced by long-term hearing aid use.

The aim of this study was to explore possible differences in the perception of loudness between long-term hearing aid full-time users and non-users. Categorical loudness scaling using pure-tone stimuli was carried out by hearing-impaired subjects. The mean levels of loudness categories at one frequency (hearing threshold: 50-75 dB HL) in a group of 18 hearing aid users (daily use < or = 15 hours per day) were compared with the corresponding levels found in 18 hearing-impaired non-users with the same distribution of hearing thresholds. The results show that, for hearing losses of 50-75 dB HL, the mean level rated as 'loud' by long-term full-time users of hearing aids is 4.5 dB above the mean level of the corresponding category rated by non-users. This difference is statistically significant (P<0.05). No significant differences were found for the lower categories. Among those subjects who had been wearing hearing aids for at least six months, no significant correlation was found between the levels of the 'loud' category and the length of time that hearing aids had been used.     

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.