A cross-over study of side of hearing aid provision

No previous study has investigated which ear should be fitted with a hearing aid. Fifty-eight patients with bilateral hearing loss of 25-75 dB HL were sequentially fitted with an ear level hearing aid for 10 weeks in each ear. Patients were then asked their preference for side of fitting, and their reasons for this preference. Thirty-five patients had symmetrical hearing: 17 (49%) preferred one ear because they could hear better with the aid in that ear, and 12 (34%) chose one side for practical reasons. Twenty-three patients had asymmetrical hearing: 8 (35%) preferred one side for practical reasons, and 13 (57%) could hear better with the aid in one ear, which was invariably the poorer hearing ear. As the preferred ear cannot be reliably predicted, bilateral ear moulds should be provided. If only one mould is provided, it should be for the poorer hearing ear.     

Benefits of amplification for unaided speech discrimination in age-related hearing loss with flat type audiogram

ObjectiveThe present study aimed to investigate whether hearing aid use can induce improvement as acclimatization effect in unaided speech perception in patients with age-related hearing loss.MethodsFifty ears in 41 patients (age range: 65-91 years) diagnosed as age-related hearing loss were enrolled in this study. They used hearing aids for more than 8 hours per day. Unaided speech audiometry using 67-S Japanese monosyllabic word list was performed one or two years after the commencement of hearing aid use. The changes in the unaided speech discrimination score before and after the commencement of hearing aid use were analyzed. To investigate factors for improvement, the patients’ backgrounds in terms of age, sex, pure tone average, unaided maximum speech discrimination score, fitting period (one year/two years), fitting ear (bilateral/unilateral), audiogram type (flat-type/other-type), and the level of amplification were also analyzed.ResultsSignificant improvement in the unaided speech discrimination score after hearing aid use was seen only in the flat-type audiogram group. More than half of older patients in the flat-type audiogram group improved their unaided maximum speech discrimination score 10 % or more. The analysis of aided hearing thresholds revealed that the flat-type audiogram group had significantly lower thresholds of 3kHz and 4kHz than the other-type audiogram group. The age, sex, pure tone average, fitting period, fitting ear, functional gain were not influential factors for improvement. On the other hand, unaided maximum speech discrimination score before using hearing aid and aided hearing threshold at 4kHz had a negative correlation with improvement.ConclusionThe findings suggested that older patients with age-related hearing loss whose audiogram is a flat type can benefit from amplification as means of improving their unaided speech perception since flat-type audiogram can be more easily adjusted to sufficiently amplify speech sound at high frequencies. It should be considered that the potential for experience-dependent plasticity is retained even in older adults.     

Optimum side for fitting a monaural hearing aid. 3. Preference and benefit

Benefit from a simulated monaural hearing aid was assessed in diotic and dichotic listening conditions in 92 subjects with bilateral, mild to moderate sensorineural hearing impairment. In diotic conditions, subjects scored better on a speech identification task with an 'aid' in their better hearing ear. However, in dichotic conditions, a 'hearing aid' the better hearing ear was of no benefit when the signal came from the side of the poorer ear, while a 'hearing aid' in the poorer ear was of benefit in all listening situations. These results support the hypothesis that patients' preference for using an aid in their poorer hearing ear (Swan et al., 1987) is based on the desire to minimise their disability in the most disadvantageous listening situations.     

Population study of the ability to benefit from amplification and the provision of a hearing aid in 55-74-year-old first-time hearing aid users

About 40% of 55-74-year-olds have an impairment in at least one ear of 25+ dB HL, and 27% have bilateral impairment at this level, with 11% being impaired bilaterally at 35+ dB HL. Only 6% currently use a hearing aid. The performance of a random sample of participants aged 55-74 years on speech-in-noise tasks shows that significant statistical benefit was obtained from bilateral amplification in over 20% of the population who do not currently use a hearing aid. The offer of a hearing aid to all those who exceeded a 25 dB HL criterion in the worse car was accepted and taken up by 40%, with 16% declining and the remainder being excluded for pathological and logistic reasons (e.g. hearing loss profile not suitable for aid). This is a very high rate of 71% acceptance. One in four fitted with the hearing aid showed a statistical advantage for hearing speech in noise in freefield (noise and speech from in front) with the hearing aid. Thus at least 10% of the population who do not currently use an aid would benefit substantially from a hearing aid in a quiet speech-in-noise environment. Those with poorer cognitive function show greater benefit overall and less disadvantage in very bad signal-to-noise environments. The overall pattern of results support screening and providing hearing aids to those who do not currently have an aid(s), and suggests that there would be considerable population benefit. At least two main questions for further research remain: (1) would bilateral aiding strategies give greater benefit; and (2) would different hearing aids and fitting strategies be more appropriate for people with differing 'cognitive task' loadings on phonological memory and lexical decision factors?     

Optimum side for fitting a monaural hearing aid. 2. Measured benefit

The benefit obtained from wearing a hearing aid in either ear was assessed in 52 subjects using an audiovisual test. The sound source was located directly in front of the subject. Overall the subjects obtained more benefit with their aid in their better hearing ear, despite having expressed a preference for using the aid in their poorer hearing ear. Seven of the subjects who had asymmetrical hearing were tested further using an auditory test with the sound source either in front of the subject or to either side. The results suggest that the subjects' preference for the poorer hearing ear are based on a desire to minimise their disability in the most disadvantageous listening situations.     

Bilateral hearing loss due to a meningioma located in the left posterior fossa: a case report

We report the case of a 39-year-old woman with a left side meningioma, suffering from bilateral sensorineural hearing loss, who recovered audiometric hearing in both ears after surgery. A preoperative pure tone audiogram (PTA) revealed a bilateral sensorineural hearing loss. Several examinations for sensorineural hearing loss indicated cochlear and retrocochlear hearing loss in the left ear and cochlear hearing loss in the right ear. After the operation, bilateral hearing loss due to a left posterior fossa meningioma gradually improved. One year after surgery, with the exception of hearing at frequencies of 4 and 8 kHz in the left ear, the postoperative audiogram had improved to an almost normal level. We speculate that hearing loss in the left ear may have been induced by the indirect compression of the cochlear nerve caused by the tumor's edema, whereas that in the right ear may have resulted from changes in CSF pressure caused by the mass effects of the tumor.     

Auditory localization under conditions of unilateral fitting of different hearing aid systems.

The spatial localization function of hearing-impaired listeners, usually fitted bilaterally with BTE, ITE or ITC devices, was tested under conditions of unilateral fitting of each of their own hearing aids, and unilateral fitting of stock versions of each of the other types. For the BTE wearers average localization accuracy and individual variability were not greatly changed when wearing only their left ear device, compared with bilateral aided performance. In ITE wearers, unilateral fitting in either ear led to somewhat poorer performance than bilateral. In the ITC wearers unilateral fitting produced inconsistent outcomes. Both BTE and ITE wearers fared poorly when fitted unilaterally with stock forms of devices 'foreign' to them, whereas ITC wearers did not show such a contrasting outcome. A group of non-impaired listeners showed severe disruption of localization under unilateral BTE and ITC hearing aid conditions, and to a lesser extent with ITEs. Results for the hearing-impaired listeners are interpreted in terms of adaptation to different usage patterns, with BTE wearers suggested as having adapted to their own systems unilaterally as well as bilaterally.     

Predicting directional hearing aid benefit for individual listeners

The fitting of directional microphone hearing aids is becoming increasingly more routine, and this fitting option has proven to be a successful method to improve speech intelligibility in many noisy listening environments. Data suggest, however, that some hearing-impaired listeners receive significantly more directional benefit than others. It is of interest, therefore, to determine if directional benefit is predictable from identifiable audiologic factors. In this report, we examined whether the slope of audiometric configuration, amount of high-frequency hearing loss, and/or the aided omnidirectional performance for a speech-in-noise intelligibility task could be used to predict the magnitude of directional hearing aid benefit. Overall results obtained from three separate investigations revealed no significant correlation between the slope of audiometric configuration or amount of high-frequency hearing loss and the benefit obtained from directional microphone hearing instruments. Although there was a significant, negative relationship between aided omnidirectional performance and the directional benefit obtained in one study, there was considerable variability among individual participants, and nearly all of the listeners with the best omnidirectional hearing aid performance still received significant additional benefit from directional amplification. These results suggest that audiologists should consider the use of directional amplification for patients regardless of audiogram slope, high-frequency hearing loss, or omnidirectional speech intelligibility score.     

Should a hearing aid in the contralateral ear be recommended for children with a unilateral cochlear implant?

OBJECTIVES: To predict bimodal benefit before cochlear implantation, we compared the performances of participants with bimodal fitting and with a cochlear implant alone on speech perception tests. METHODS: Twenty-two children with a cochlear implant in one ear and a hearing aid in the other (bimodal fitting) were included. Several aided and unaided average hearing thresholds and the aided word recognition score of the hearing aid ear were related to the bimodal benefit on a phoneme recognition test in quiet and in noise. Results with bimodal fitting were compared to results with the cochlear implant alone on a phoneme recognition test in quiet and in noise. RESULTS: No relationship was found between any of the hearing thresholds or the aided phoneme recognition score of the hearing aid ear and the bimodal benefit on the phoneme recognition tests. At the group level, the bimodal scores on the phoneme recognition tests in quiet and in noise were significantly better than the scores with the cochlear implant alone. CONCLUSIONS: Preoperatively available audiometric parameters are not reliable predictors of bimodal benefit in candidates for cochlear implantation. Children with unilateral implants benefit from bimodal fitting on speech tests. This improvement in performance warrants the recommendation of bimodal fitting even when bimodal benefit cannot be predicted.     

High-frequency amplification with ITC-HA and BTE-HA. A comparative investigation.

The purpose of the present investigation was to evaluate the magnitude of selective high-frequency amplification obtained by an in-the-canal hearing aid (ITC-HA), and to compare it with that obtained with a conventional behind-the-ear hearing aid (BTE-HA) with an open mould. 22 subjects (20 males, 2 females) at a median age of 66 years (range 46-84) were included in the investigation. All suffered from a bilateral high-frequency hearing loss with normal or near-normal hearing thresholds at 0.5 and 1 kHz. Insertion gain measurements demonstrated that the ITC-HA gives a significantly higher amplification in the high-frequency area, when compared with the BTE-HA, though neither of the hearing aids amplified as much as indicated by the POGO strategy. Although a better amplification in the high-frequency area was obtained with the ITC-HA, it did not result in significantly better speech recognition when compared with the BTE-HA. At the hearing aid fitting, all subjects preferred the ITC-HA, and after an observation period of one year, 68% of those fitted used the aid continuously. Based on the investigation it is concluded that hearing-impaired persons can be fitted with an ITC-HA, even if they have pronounced high-frequency hearing loss, and that this type of aid is preferred by the hearing-impaired to the conventional BTE-HA.     

Comparison of three procedures for initial fitting of compression hearing aids. II. Experienced users, fitted unilaterally

This paper is the second in a series comparing three procedures for the initial fitting of multichannel compression hearing aids. The first paper reported the results for a group of 10 experienced hearing aid users fitted bilaterally. This paper reports the results for a different group of 10 experienced hearing aid users fitted unilaterally. The three procedures were: (1) CAMEQ, which aims to amplify speech so as to give equal loudness per critical band over the frequency range 500-5000 Hz, and to give similar overall loudness to normal over a wide range of speech levels; (2) CAMREST, which aims to amplify speech so as to restore normal specific loudness patterns, over a wide range of speech levels; and (3) DSL [i/o], which aims to map the dynamic range of normal-hearing people into the reduced dynamic range of hearing-impaired people, with full restoration of audibility. Each subject was fitted with one Danalogic 163D digital hearing aid, using each of the three fitting procedures in turn; the order was counter-balanced across subjects. Prescribed insertion gains for 55 and 80 dB SPL input levels were verified using real-ear measurements. Immediately after fitting with a given procedure, and 1 week after fitting. the gains were adjusted, when required, by the minimum amount necessary to achieve acceptable fittings. On average, the adjustments were smallest for the CAMREST procedure, slightly larger for the CAMEQ procedure, and largest of all for DSL [i/o]. For the DSL [i/o] the gain changes were mostly negative, especially for high frequencies and the higher input level. After these gain adjustments, users wore the aids for at least 3 weeks before speech reception thresholds (SRTs) for sentences in quiet and in steady and fluctuating background noise were measured. The APHAB questionnaire was also administered. The hearing aids were then refitted with the next procedure. SRTs and APHAB scores did not differ significantly between the three procedures. We conclude that the CAMEQ and CAMREST procedures provide a more appropriate initial fitting than DSL [i/o] for unilaterally experienced hearing aid wearers. Comparison with our earlier study based on bilateral fittings suggests that the preferred gains are similar for unilateral and bilateral fittings.     

Long-term results of bone-anchored hearing aid recipients who had previously used air-conduction hearing aids

OBJECTIVE: To study the long-term results (use, care, satisfaction, ear infections, and audiometry) of the application of a bone-anchored hearing aid (BAHA) to patients with conventional indications who had previously used air-conduction hearing aids. DESIGN: Follow-up study (mean duration, 9 years). SETTING: Tertiary referral center. PATIENTS: The study population comprised 27 patients with conductive or mixed hearing loss and who had participated in a previous study (N = 34). Seven could not be included anymore as a result of death, Alzheimer disease, or problems related to the implant. Everyone filled out the questionnaire, and 23 patients underwent audiometric evaluation. MAIN OUTCOME MEASURES: The patients filled out the adapted Nijmegen questionnaire. Aided free-field thresholds were measured as well as scores for speech in noise and in quiet. Results were compared with those obtained in the initial study. RESULTS: All 27 patients were still using their BAHA and appreciated it with regard to speech recognition in quiet, sound comfort, and improvements in ear infections. The audiometric results showed that most patients tested had stable bone-conduction thresholds over the years (after correction for age). Despite the treatment with BAHA, a significant deterioration in the cochlear hearing was observed in the other patients in the ear under study (their best hearing ear). CONCLUSIONS: Positive patient outcome measures emphasized the importance of BAHA application to patients with conventional indications. The audiometric data showed fairly stable cochlear function but not for all patients. This underlines that conservative treatment should be chosen (fitting of bone-conduction devices).     

Discrimination vocale en présence de bruit dans les différents types de surdité

Speech Discrimination in Presence of Noise in Different Kinds of Hearing Loss

When the threshold of hearing was poorer than 70 dB HL, the speech audiometric curve was always made worse by the presence of noise. By contrast, if the threshold was better than 70 dB HL, the speech audiometric curve was improved by noise in 35% of cases. This effect was particularly noticeable in the case of cupul-shaped or ‘plateau’-shaped speech curves

In conductive hearing losses, the effect of noise was always to produce a deterioration in the speech audiogram, This is in contrast to what one would expect in view of a paracousis willisii     

Comparison of two adaptive procedures for fitting a multi-channel compression hearing aid

We compared two adaptive procedures for fitting a multi-channel compression hearing aid. "Camadapt" uses judgements of the loudness of speech stimuli and the tonal quality of music stimuli. "Eartuner" uses judgements of the loudness and clarity of speech stimuli with differing spectral characteristics. Sixteen new users of hearing aids were fitted unilaterally, using each procedure. The fittings were assigned to Programs 1 and 2 in the aid, in a counter-balanced order. Subjects kept a diary of their experiences with each program in everyday life. Following 2-4 weeks of experience, they filled in the APHAB and other questionnaires and were re-fitted using both procedures. Camadapt generally led to higher low-level gains and lower high-level gains than Eartuner. Gains recommended by the procedures did not change following experience. Eight subjects preferred the Camadapt fitting and eight preferred the Eartuner fitting. Most subjects gave high overall satisfaction ratings for both procedures. Test-retest reliability was better for Eartuner than for Camadapt. Preference for the Camadapt fitting was associated with slightly better speech communication with Camadapt, while preference for the Eartuner fitting was associated with fewer problems with aversion for that procedure.     

Comparison of two adaptive procedures for fitting a multi-channel compression hearing aid

We compared two adaptive procedures for fitting a multi-channel compression hearing aid. “Camadapt” uses judgements of the loudness of speech stimuli and the tonal quality of music stimuli. “Eartuner” uses judgements of the loudness and clarity of speech stimuli with differing spectral characteristics. Sixteen new users of hearing aids were fitted unilaterally, using each procedure. The fittings were assigned to Programs 1 and 2 in the aid, in a counter-balanced order. Subjects kept a diary of their experiences with each program in everyday life. Following 2-4 weeks of experience, they filled in the APHAB and other questionnaires and were re-fitted using both procedures. Camadapt generally led to higher low-level gains and lower high-level gains than Eartuner. Gains recommended by the procedures did not change following experience. Eight subjects preferred the Camadapt fitting and eight preferred the Eartuner fitting. Most subjects gave high overall satisfaction ratings for both procedures. Test-retest reliability was better for Eartuner than for Camadapt. Preference for the Camadapt fitting was associated with slightly better speech communication with Camadapt, while preference for the Eartuner fitting was associated with fewer problems with aversion for that procedure.     

Negative consequences of uncorrected hearing loss--a review

Hearing loss gives rise to a number of disabilities. Problems in recognizing speech, especially in difficult environments, give rise to the largest number of complaints. Other kinds of disabilities may concern the reduced ability to detect, identify and localize sounds quickly and reliably. Such sounds may be warning or alarm signals, as well as music and birds singing. The communicative disability affects both hearing-impaired people and other people in their environment--family members, fellow workers, etc. Hearing-impaired people are not always aware of all the consequences of the impairment; they do not always know what they are missing. Several studies have shown that uncorrected hearing loss gives rise to poorer quality of life, related to isolation, reduced social activity, and a feeling of being excluded, leading to an increased prevalence of symptoms of depression. These findings indicate the importance of early identification of hearing loss and offers of rehabilitative support, where the fitting of hearing aids is usually an important component. Several studies also point to a significant correlation between hearing loss and loss of cognitive functions. Most of these studies show such a correlation without being able to show whether the hearing loss caused the reduction in cognitive performance or if both the hearing loss and the cognitive decline are parts of a common, general age-related degeneration. A couple of these studies, however, indicate that the uncorrected hearing loss may be the cause of cognitive decline. Whichever alternative is true, the correlation should be seen as a clear indication for early hearing aid fitting for those needing it. Monaural hearing aid fitting in subjects with bilateral hearing loss may give rise to a reduced ability to recognize speech presented to the unaided ear, the so-called late-onset auditory deprivation effect. This functional decline is reversible in some but not all subjects after fitting of a hearing aid also on the previously unaided ear.     

Comparison of hearing aids over the 20th century

OBJECTIVE: To measure hearing aid performance using circuitry representative of the major eras of technological advancement during the 20th century. DESIGN: Twenty subjects with audiometric profiles consistent with hearing aid candidacy were fit with each of seven hearing aids. No directional microphones were used and binaural benefit was not assessed. Each hearing aid was fit to the strategy or fitting scheme of the era, or that which was intended by the presenting manufacturer. Electroacoustic and/or real ear measures of gain, output, bandwidth, and distortion were obtained. Objective outcome measures assessing speech perception in backgrounds of noise were obtained. Subjective outcome measures of sound quality and ease of listening were obtained in the laboratory and in real life settings. RESULTS: Electroacoustic and real ear measures indicate that gain and bandwidth have increased, and output and distortion have decreased with current electronic aids. Speech perception ability across the different outcome measures showed significantly poorer performance with the body and linear hearing aids when input levels were high; when input levels were low, outcome measures with hearing aids using a dynamic range compression were not negatively affected. At the most adverse signal to noise ratios, none of the hearing aids was shown to be superior. Measured bandwidth did not correlate highly with speech perception ability for any of the objective outcome measures used. For the subjective measures of sound quality done in a blinded manner, no significant differences were found across different listening situations for current hearing aids. CONCLUSIONS: The two most important factors for aided speech perception appear to be the audibility and distortion of the signal. No current compression scheme proved superior with the outcome measures used in this investigation.     

Requirements on speech processing hearing aids for the profoundly deaf, some preliminary remarks.

Many severely hard of hearing and profoundly deaf persons seem to get very little help from an ordinary hearing aid. This observation has prompted the development of tactile speech processing aids. These aids should however only be used if it can be shown that the subject has no useful residual hearing. In the case of a profound hearing loss the audiogram might in some cases show tactile sensations in the ear. To get a better estimation of the remaining auditory capacity experiments have been made with frequency discrimination measurements, and with speech tests consisting of rhyming word pairs. Results from these different tests are summarized in relation to an audiogram classification system. Two tactile speech processing aids are described. Evaluation studies with these aids show positive results but these results must be compared with the results that can be obtained with ordinary hearing aids and different types of auditory speech processing hearing aids. The possibility to use extreme auditory recording must also be studied. In this case the transmitted signal is not speech-like and it is possible that this limits their usefulness. Experiments with this type of aids might however give valuable information about how the human perceptual systems process signals derived from the original speech signal.