Behind-the-ear Hearing Aid Research Articles

Improving speech intelligibility in noise and spatial perception: the critical role of hearing aid microphone position.

Hearing aid (HA) manufacturers have introduced behind-the-ear (BTE) models where the microphone is positioned in the ear canal, which could impact auditory performance by distorting the pinna's acoustic cues. This study aimed to compare two different BTE HAs with varying microphone positions: the receiver in the ear (RITE) and the transducer in the ear (TIE). The study involved 10 participants who had never used HAs before. They used both RITE and TIE HAs bilaterally for 3 weeks. Auditory performance was assessed through free field hearing assessments (hearing thresholds, speech recognition threshold, and speech discrimination score), the Turkish Matrix Sentence Test (TURMatrix), a sound localization test, and the Satisfaction with Amplification in Daily Living (SADL) questionnaire. There was no significant difference between TIE and RITE in the free field hearing assessments. However, TIE outperformed RITE in non-adaptive TURMatrix scores in quiet, adaptive TURMatrix scores in noise, and sound localization accuracy at various angles. SADL sub-scores (Positive Effect, Service and Cost, and Personal Image) and overall satisfaction scores were significantly better for TIE. The microphone position in HAs can influence auditory performance. This study demonstrated that TIE provided better speech intelligibility, localization accuracy, and user satisfaction compared to RITE.

Compensation effect of hearing aid on speech recognition in noise in patients with unilateral hearing loss

Objective:The aim of this study was to investigate the speech recognition in noise in patients with unilateral hearing loss（UHL）, and explore the compensation effect of behind-the-ear（BTE） hearing aid on speech recognition in patients with varied degrees of UHL. Methods:Twenty-five participants with UHL were divided into two groups according to the degree of hearing loss: one group included subjects with unilateral moderate and moderately severe hearing loss and another one included subjects with unilateral severe and profound hearing loss. Fifteen healthy subjects with normal hearing were enrolled as the control group. The speech recognition thresholds and speech recognition scores at fixed signal noise ratio（SNR） in UHL participants with and without BTE hearing aid were tested in the sound field and compared with those in the control group. One-way ANOVA was used to examine the significance of the difference between UHL participants and control group, and paired t-test was used to analyze the compensation effect of hearing aid on speech recognition in noise in UHL participants. Results:The speech recognition thresholds were significantly higher in both UHL groups（P<0.01） compared with the control group, there was no significant difference between two UHL groups. And the speech recognition scores were significantly lower when the SNR was fixed（P<0.01）, and there were no significant differences between two UHL groups. When fitting BTE hearing aid, the speech recognition thresholds of the two groups significantly decreased（P<0.01）, and the speech recognition scores significantly improved（P<0.01）. Conclusion:Patients with above moderate UHL presented a significant decrease in performance of speech recognition in noise, and fitting BTE hearing aid on the affected ear had a positive compensation effect.

Children with Conductive Hearing Loss Fitted with Hearing Aids: Outcomes and Caregiver Experiences in South Africa.

Introduction Hearing aids are a frequent management option for children with conductive hearing loss (CHL) and it is necessary to determine the efficacy of outcomes. Limited information regarding caregivers' perceptions and experiences are available to examine outcomes in this population. Objectives To describe hearing aid outcomes and caregivers' experiences for children with CHL who wear behind-the-ear (BTE) hearing aids. Methods Retrospective review of clinical data from 19 children between 0 and 13 years of age with CHL, who were fitted with BTE hearing aids between January 2017 and March 2020. Hearing aid outcomes were documented at one month post-hearing aid fitting, via average daily use and caregiver and teacher reports obtained through the Parents' Evaluation of Aural/oral performance of Children (PEACH) and the Teachers' Evaluation of Aural/oral performance of Children (TEACH). Telephonic surveys were conducted with 13 caregivers to explore their experiences. Qualitative data from open-ended questions were analyzed thematically. Results The average hearing aid use was 6.5 hours/day (2.0 standard deviation, SD; range 4.1-10.3) for bilateral hearing aid users. Questionnaire results indicated that most children (PEACH - 83.3% and TEACH - 92.3%) used their hearing aids more than 75% of the time. Participants performed better in quiet environments with limited sensitivity to loud sounds at home and at school. Reported challenges included stigma and device compliance. Conclusions Children with CHL used their hearing aids for comparable hours (5-8 hours/day), as reported for children with sensorineural hearing loss, but less than the recommended 10 hours/day required for adequate language development. Caregivers reported benefits equivalent to expectations, with challenges similar to those reported in high-income countries.

The comparison of gains prescribed for digital behind-the-ear hearing aids using the manufacturer-specific and conventional prescriptive formulas

Background and Aim: There are several prescriptive formulas for covering a variety of hearing loss, each of which applies relatively different amplifications at different frequencies. This study aims to compare the gains prescribed for digital behind-the-ear (BTE) hearing aids by the Desired Sensation Level Multi-Stage [Input/Output] (DSLm[I/O]), National Acoustic Laboratories-non linear2 (NAL-NL2) and manufacturer-specific formulas at different levels of input intensity. Methods: The gain values in 12-channel BTE hearing aids prepared from four companies (Oticon, Phonak, ReSound and Siemens) were measured at three levels of input intensity (45, 65, and 85 dB SPL) and at a frequency range of 250−8000 Hz for two moderately severe flat and mild sloping to severe hearing losses by using the DSLm[I/O], NAL-NL2 and manufacturerspecific formulas in the Frye FP35 test box. Results: There was no significant difference between the four selected hearing aids in terms of prescribed gain values using the prescriptive formulas (p &gt; 0.05). Conclusion: The DSLm[I/O] formula prescribes higher gain in the 12-channel BTE hearing aids from Oticon, Phonak and Siemens companies at all input intensities and frequencies for moderately severe flat and mild sloping to severe hearing losses compared to the NAL-NL2 formula and manufacturer-specific formulas (Voice Aligned Compression (VAC), Adaptive Phonak, Connexx Fit and audiogram+). Keywords: National acoustic laboratories-non linear2; desired sensation level multi-stage [input/output]; gain; frequency; intensity levels

New Evidence-based Fitting Paradigm for Over-the-Counter Hearing Aids

New Evidence-based Fitting Paradigm for Over-the-Counter Hearing Aids

Open-Fit Domes and Children with Bilateral High-Frequency Sensorineural Hearing Loss: Benefits and Outcomes.

Open-fit domes (OFDs) coupled with behind-the-ear (BTE) hearing aids were designed for adult listeners with moderate-to-severe bilateral high-frequency hearing loss (BHFL) with little to no concurrent loss in the lower frequencies. Adult research shows that BHFL degrades sound localization accuracy (SLA) and that BTE hearing aids with conventional earmolds (CEs) make matters worse. In contrast, research has shown that OFDs enhance spatial hearing percepts in adults with BHFL. Although the benefits of OFDs have been studied in adults with BHFL, no published studies to date have investigated the use of OFDs in children with the same hearing loss configuration. This study seeks to use SLA measurements to assess efficacy of bilateral OFDs in children with BHFL. To measure SLA in children with BHFL to determine the extent to which hearing loss, age, duration of CE use, and OFDs affect localization accuracy. A within-participant experimental design using repeated measures was used to determine the effect of OFDs on localization accuracy in children with BHFL. A between-participant experimental design was used to compare localization accuracy between children with BHFL and age-matched controls with normal hearing (NH). Eighteen children with BHFL who used CE and 18 age-matched NH controls. Children in both groups were divided into two age groups: older children (10-16 yr) and younger children (6-9 yr). All testing was done in a sound-treated booth with a horizontal array of 15 loudspeakers (radius of 1 m). The stimulus was a spondee word, "baseball": the level averaged 60 dB SPL and randomly roved (±8 dB). Each child was asked to identify the location of a sound source. Localization error was calculated across the loudspeaker array for each listening condition. A significant interaction was found between immediate benefit from OFD and duration of CE usage. Longer CE usage was associated with degraded localization accuracy using OFDs. Regardless of chronological age, children who had used CEs for <6 yr showed immediate localization benefit using OFDs, whereas children who had used CEs for >6 yr showed immediate localization interference using OFDs. Development, however, may play a role in SLA in children with BHFL. When unaided, older children had significantly better localization acuity than younger children with BHFL. When compared to age-matched controls, children with BHFL of all ages showed greater localization error. Nearly all (94% [17/18]) children with BHFL spontaneously reported immediate own-voice improvement when using OFDs. OFDs can provide sound localization benefit to younger children with BHFL. However, immediate benefit from OFDs is reduced by prolonged use of CEs. Although developmental factors may play a role in improving localization abilities over time, children with BHFL will rarely equal that of peers without early use of minimally disruptive hearing aid technology. Also, the occlusion effect likely impacts children far more than currently thought.

Correlation of flow field and acoustic output from hearing aids under influence of wind

Wind noise in hearing aids occurs even at low wind speeds and is a confounding factor for hearing aid wearer, hence leading to a reduction of speech intelligibility. In this submission, a study on the correlation of the flow field around a hearing aid to its acoustic output is made. The BTE (behind the ear) hearing aid is mounted on an artificial head with three different ear geometries. The flow field is captured using a two component PIV (particle image velocimetry) system. For exposing critical flow phenomena, a POD (proper orthogonal decomposition) of the PIV measurement data is made. The hearing aid output is measured with a microphone inside the artificial head. On the one hand, wind noise in hearing aids is generated by the fluctuating velocity field of the boundary layer on the hearing aid. On the other hand, based on the PIV data and the POD results, flow patterns around the artificial head and the hearing aid are detected, which cause further noise, that is captured by the hearing aid microphones. With these findings, modifications on the hearing aid geometry are deduced, that lead to a decrease in wind noise and hence to a better speech intelligibility.

Effectiveness of Low Cut Modified Amplification using Receiver in the Canal Hearing Aid in Individuals with Auditory Neuropathy Spectrum Disorder.

Introduction The studies on hearing aid benefit in individuals with auditory neuropathy spectrum disorder (ANSD) shows limited benefit. Low cut modified amplification is found to be effective in few individuals with ANSD. With advancement in technology, receiver in the canal (RIC) hearing aids have proven to be more effective than traditional behind the ear (BTE) hearing aids. Objective Thus, the present study attempts to determine the effectiveness of low cut modified amplification using RIC and BTE. Method Twenty participants with ANSD were fitted with BTE and RIC using traditional and low cut modified amplification. We divided them into good and poor performers based on unaided speech identification scores (SIS). We then compared aided SIS and aided benefit across conditions in good and poor performers with ANSD across both conditions using BTE and RIC. Results The results of the study showed that the aided performance improved with low cut modified amplification in both BTE and RIC hearing aids. The improvement noticed with low-cut modified fitting with RIC was significant in more than BTE, especially in good performers with ANSD. Conclusion The improved clarity and naturalness of sound with RIC may have led to better aided scores and better acceptance of the hearing aid. Thus, low-cut modified amplification, preferably with RIC, needs to be attempted in fitting individuals with ANSD, especially in those with good unaided SIS in quiet.

The Hearing Aid ‘Effect’ as a Function of Race and Gender

The Hearing Aid ‘Effect’ as a Function of Race and Gender

Development of monaural and binaural behind-the-ear cartilage conduction hearing aids

Hosoi (2004) found a pathway for clear sound transmission via aural cartilage. Our research group is developing a new hearing aid using this mechanism. The cartilage conduction hearing aid can be used in patients who cannot insert the earplugs of conventional hearing aids. The cartilage conduction hearing aid (model HD-GX) is composed of a main unit, a transducer, and a fitting part. The ring-shaped fitting part is placed in the entrance of the ear canal, and the vibration at the cartilage then generates sound in the external auditory canal. The cartilage conduction sound remains in the canal and reduces the risk of acoustical feedback. Considering this advantage, we designed it to wear behind the ear (BTE) (model HD-GX2). As binaural cartilage conduction can present sound directivity equivalent to that of air conduction, we then developed a binaural cartilage conduction hearing aid (model HD-GX3) by combining two BTE hearing aids.

Evaluation of a Pinna Compensation Algorithm for Sound Localization and Speech Perception in Noise

This study was designed to evaluate the effect of a pinna compensation (PC) algorithm on localization performance in the horizontal plane and speech intelligibility in noise. Nine and 18 experienced hearing aid users with bilaterally symmetrical sensorineural hearing loss participated in the localization study and the speech-in-noise study, respectively. Performance was evaluated unaided, aided with a behind-the-ear (BTE) hearing aid with an omnidirectional microphone (Omni), and aided with the same hearing aid with the PC algorithm (Omni+PC). Localization performance was measured using 12 loudspeakers spaced 30° apart on a horizontal plane. Speech-in-noise performance was measured with speech presented from 0° or 180°. A single-blinded, repeated measures design was used. Significant improvement in localization accuracy was found when comparing the Omni+PC condition to the Omni condition. Also, the Omni+PC condition improved the signal-to-noise ratio by 2.4 dB when compared to the Omni condition when speech was presented from the front in a diffuse noise background. Use of the PC algorithm improved localization on the horizontal plane and speech-in-noise performance. These results support use of the PC algorithm in BTE hearing aid fittings.

Localization of virtual sound sources with bilateral hearing aids in realistic acoustical scenes

Sound localization with hearing aids has traditionally been investigated in artificial laboratory settings. These settings are not representative of environments in which hearing aids are used. With individual Head-Related Transfer Functions (HRTFs) and room simulations, realistic environments can be reproduced and the performance of hearing aid algorithms can be evaluated. In this study, four different environments with background noise have been implemented in which listeners had to localize different sound sources. The HRTFs were measured inside the ear canals of the test subjects and by the microphones of Behind-The-Ear (BTEs) hearing aids. In the first experiment the system for virtual acoustics was evaluated by comparing perceptual sound localization results for the four scenes in a real room with a simulated one. In the second experiment, sound localization with three BTE algorithms, an omnidirectional microphone, a monaural cardioid-shaped beamformer and a monaural noise canceler, was examined. The results showed that the system for generating virtual environments is a reliable tool to evaluate sound localization with hearing aids. With BTE hearing aids localization performance decreased and the number of front-back confusions was at chance level. The beamformer, due to its directivity characteristics, allowed the listener to resolve the front-back ambiguity.

Data mining of audiology patient records: factors influencing the choice of hearing aid type

BackgroundThis paper describes the analysis of a database of over 180,000 patient records, collected from over 23,000 patients, by the hearing aid clinic at James Cook University Hospital in Middlesbrough, UK. These records consist of audiograms (graphs of the faintest sounds audible to the patient at six different pitches), categorical data (such as age, gender, diagnosis and hearing aid type) and brief free text notes made by the technicians. This data is mined to determine which factors contribute to the decision to fit a BTE (worn behind the ear) hearing aid as opposed to an ITE (worn in the ear) hearing aid.MethodsFrom PCA (principal component analysis) four main audiogram types are determined, and are related to the type of hearing aid chosen. The effects of age, gender, diagnosis, masker, mould and individual audiogram frequencies are combined into a single model by means of logistic regression. Some significant keywords are also discovered in the free text fields by using the chi-squared (χ2) test, which can also be used in the model. The final model can act a decision support tool to help decide whether an individual patient should be offered a BTE or an ITE hearing aid.ResultsThe final model was tested using 5-fold cross validation, and was able to replicate the decisions of audiologists whether to fit an ITE or a BTE hearing aid with precision in the range 0.79 to 0.87.ConclusionsA decision support system was produced to predict the type of hearing aid which should be prescribed, with an explanation facility explaining how that decision was arrived at. This system should prove useful in providing a "second opinion" for audiologists.

Binaural Directivity Patterns for Normal and Aided Human Hearing

The aim of this brief report was to investigate binaural directivity patterns for normal and aided hearing, as opposed to conventional monaural measures. Head-related transfer functions for an artificial head measured at the entrance to the ear canal and above the pinnae and a binaural loudness model for directional sounds were used to estimate binaural directivity patterns for normal human hearing and behind-the-ear (BTE) hearing devices in the horizontal plane. The results show that binaural directivity patterns are smoother than the corresponding monaural patterns, and that there are clear frequency-dependent differences in binaural directivity between the two measurement positions. The data can be used in the signal processing of BTE hearing aid systems to mimic the binaural directivity of normal, unoccluded ears.

Hearing Aids in the Real World: Use of Multimemory and Volume Controls

Despite advances in technology, hearing aid users continue to express a desire for some control over their devices. Access to a suitable control can significantly affect overall satisfaction with amplification, yet little is known about the circumstances that drive hearing aid users to manipulate controls. Such information would be useful in guiding clinical decisions about the selection of controls and synchronization of their operation in a bilateral pair of hearing aids. The purpose of this study was to examine the real-world use of multimemory (MM) and volume (VC) controls and environmental characteristics that may influence their use. Real-time data about MM and VC usage were gathered in the real world. Subjective reports of the environmental characteristics were obtained. This design allowed examination of the nature of hearing aid adjustments as well as exploration of factors affecting them. Ten adults with bilaterally symmetric, mild-to-moderate sensorineural hearing loss participated in the study. All had previous experience with hearing aids. Participants were fitted bilaterally with BTE (behind-the-ear) hearing aids equipped with an MM button and/or VC wheel. The devices were connected to a PDA (personal digital assistant) that logged data from the hearing aids and stored surveys completed by participants in various listening situations. The following data were obtained from the PDA: (1) MM and VC settings in the left and right devices, (2) broadband input level at the microphone of the left and right devices, and (3) participant reports of the presence, distance, and location of signal and background noise. Prevalence of nondefault settings and bilateral symmetry of hearing aid adjustments were summarized descriptively, while the influence of environmental characteristics on hearing aid adjustments was analyzed using nonparametric methods. Over 4-5 wk, 912 hr of data were logged and 184 surveys completed. Results showed that (1) the default (i.e., the programmed or "use") setting was preferred most often, (2) the preferred hearing aid settings were mostly bilaterally symmetrical, and (3) nondefault settings were often used in difficult listening situations. The findings of this study generally support the use of synchronized MMs and/or VCs, although there may be exceptions to their utility.

Sound source localization using hearing aids with microphones placed behind-the-ear, in-the-canal, and in-the-pinna

Objective: The effect of different commercial hearing aids on the ability to resolve front-back confusions and on sound localization in the frontal horizontal and vertical plane was studied. Design: Commercial hearing aids with a microphone placed in-the-ear-canal (ITC), behind-the-ear (BTE), and in-the-pinna (ITP) were evaluated in the frontal and full horizontal plane, and in the frontal vertical plane. Study Sample: A group of 13 hearing-impaired subjects evaluated the hearing aids. Nine normal-hearing listeners were used as a reference group. Results and Conclusions: Differences in sound localization in the front-back dimension were found for different hearing aids. A large inter-subject variability was found during the front-back and elevation experiments. With ITP or ITC microphones, almost all natural spectral information was preserved. One of the BTE hearing aids, which is equipped with a directional microphone configuration, generated a sufficient amount of spectral cues to allow front-back discrimination. No significant effect of hearing aids on elevation performance in the frontal vertical plane was observed. Hearing-impaired subjects reached the same performance with and without the different hearing aids. In the unaided condition, a frequency-specific audibility correction was applied. Some of the hearing-impaired listeners reached normal hearing performance with this correction.SumarioObjetivo: Se estudio el efecto de diferentes auxiliares auditivos sobre la habilidad para resolver confusiones en dirección antero-posterior y en la localización del sonido en los planos fronto-horizontal y vertical. Diseño: Se analizaron auxiliares auditivos comerciales que tienen un micrófono localizado dentro del canal auditivo (ITC) y en la oreja (ITP) en el plano frontal, el horizontal y en el plano fronto-vertical. Muestra: Un grupo de 13 sujetos hipoacúsicos evaluaron los auxiliares auditivos. Nueve sujetos normoacúsicos sirvieron como grupo de referencia. Resultados y conclusiones: Se encontraron diferencias en la localización del sonido en la dimensión fronto-posterior con varios auxiliares auditivos. Se encontró una gran variabilidad inter-sujeto en los experimentos de dirección antero-posterior y de elevación. Uno de los auxiliares auditivos tipo curveta que está equipado con un micrófono direccional generó una cantidad suficiente de claves espectrales para poder discriminar en el plano antero-posterior. No se observó un efecto significativo de los auxiliares auditivos en el desempeño por elevación en el plano vertical. Los sujetos hipoacúsicos alcanzaron el mismo desempeño con y sin los diferentes auxiliares auditivos. Cuando los usaban se aplicó una corrección de audibilidad específica en frecuencia. Algunos de lo sujetos hipoacúsicos alcanzaron un desempeño de audición normal con esta corrección.

Hearing Aids in the Real World: Typical Automatic Behavior of Expansion, Directionality, and Noise Management

Automatic DSP (digital signal processing) features, widely available in hearing aids today, are useful because they alleviate the need for the hearing aid wearer to manually adjust the hearing aid as listening conditions change. Although the theoretical basis for the design of these features may be sound, little is known about their behavior in the real world. Data logging offers a glimpse into the life of the individual hearing aid wearer, but there are no published data to date that provide a frame of reference for the interpretation of this information. Further, data logging in hearing aids provides only aggregate summaries for individual features, ignoring complex interactions including the differences between the left and right sides of a bilateral pair. The purpose of this study was to determine the typical behavior of three automatic DSP hearing aid features-expansion, directionality, and noise management-in daily life. Ten individuals with hearing impairment were fitted bilaterally with BTE (behind the ear) hearing aids. The hearing aids were programmed for the individual's hearing loss with expansion, directionality, and noise management set to activate automatically. A PDA (personal digital assistant) logged the input level and status of expansion, directionality, and noise management from both devices at 5 sec intervals. Data were gathered in this manner over a period of 4-5 wk. A total of 741 hr of hearing aid use were logged, 50% of which were spent in environments no louder than 50 dB SPL. Expansion, directionality, and noise management were active 45, 10, and 21% of the time, respectively; the median amount of gain reduction for noise management was ∼1 dB. Although expansion and noise management were always active at the low and high input levels, respectively, activation of directionality never exceeded 50%. Expansion and noise management were sometimes active simultaneously, as were directionality and noise management. Bilateral agreement in feature activation typically exceeded 80%, except when the input level was at the cusp of a threshold for activation of a specific feature and at high input levels.

Evaluation of Nonlinear Frequency Compression for School-Age Children with Moderate to Moderately Severe Hearing Loss

Previous research has indicated that children with moderate hearing loss experience difficulty with recognition of high-frequency speech sounds, such as fricatives and affricates. Conventional behind-the-ear (BTE) amplification typically does not provide ample output in the high frequencies (4000 Hz and beyond) to ensure optimal audibility for these sounds. To evaluate nonlinear frequency compression (NLFC) as a means to improve speech recognition for children with moderate to moderately severe hearing loss. Within subject, crossover design with repeated measures across test conditions. Fifteen children, aged 5-13 yr, with moderate to moderately severe high-frequency sensorineural hearing loss were fitted with Phonak Nios, microsized, BTE hearing aids. These children were previous users of digital hearing aids and communicated via spoken language. Their speech and language abilities were age-appropriate. Aided thresholds and speech recognition in quiet and in noise were assessed after 6 wk of use with NLFC and 6 wk of use without NLFC. Participants were randomly assigned to counter-balanced groups so that eight participants began the first 6 wk trial with NLFC enabled and the other seven participants started with NLFC disabled. Then, the provision of NLFC was switched for the second 6 wk trial. Speech recognition in quiet was assessed via word recognition assessments with the University of Western Ontario (UWO) Plural Test and recognition of vowel-consonant-vowel nonsense syllables with the Phonak Logatome test. Speech recognition in noise was assessed by evaluating the signal-to-noise ratio in dB for 50% correct performance on the Bamford-Kowal-Bench Speech-in-Noise (BKB-SIN) test, an adaptive test of speech perception in a multitalker babble background. Aided thresholds for high-frequency stimuli were significantly better when NLFC was enabled, and use of NLFC resulted in significantly better speech recognition in quiet for the UWO Plural Test and for the phonemes /d/ and /s/ on the Phonak Logatome test. There was not a statistically significant difference in performance on the BKB-SIN test between the NLFC enabled and disabled conditions. These results indicate that NLFC improves audibility for and recognition of high-frequency speech sounds for children with moderate to moderately severe hearing loss in quiet listening situations.

Use of frequency transposition in a thin-tube open-ear fitting

The use of thin-tube open-ear fitting has become increasingly popular in the last few years. This type of fitting offers improvements in the wearers’ perception of their own voice, especially for people with a mild hearing loss or a highfrequency hearing loss. It also provides an instant fit, is easy to demonstrate, and improves the appearance of behind-the-ear (BTE) hearing aid to wearers. Both the acceptance rate and the return rate of these models are more favorable than the average for hearing aids overall. Although the openness of the fitting may reduce the potential improvement in signal-to-noise ratio (SNR) offered by a directional microphone, Kuk et al. have shown that an open-fit directional microphone provides an SNR improvement of 2-3 dB over the same hearing aid in its omnidirectional microphone mode. 1 On the other hand, thin-tube open-ear fittings may compromise the audibility of the high frequencies for some wearers. 2 In this paper, we will review some of these potential compromises and discuss why frequency transposition may be a solution for the limitations. We will also show that frequency transposition improves the perception of everyday sounds and may enhance consonant recognition for some people fitted with thin-tube openear devices. ISSUES WITH THIN-TUBE, OPEN-EAR FITTINGS

&lt;p&gt;Clinical trial of a low-cost, solar-powered hearing aid&lt;/p&gt;

Objective: In July 2001 the World Health Organization (WHO) launched their ‘Guidelines for hearing aids and services for developing countries’. The objective of this study was to evaluate the clinical outcome of an analogue, low-cost, behind-the-ear hearing aid (BTE-HA) that met the minimum technical requirements outlined by the WHO.&#x0D; Material and Methods: A total of 25 subjects (17 males, 8 females; median age 74 years; range 50-86 years) were recruited among patients referred for audiological evaluation who consented to participate in the trial. All subjects had a hearing loss of &lt; or = 60 dB HL at 2 kHz, were mobile and mentally unimpaired; 13 were experienced users of HAs, 3 suffered from mixed conductive/sensorineural hearing impairment (HI) and the remainder had pure sensorineural HI. Based on puretone, speech and impedance audiometry the BTE-HAs were fitted, using the National Acoustic Laboratories-R (NALR) prescription rule, 21 binaurally and 4 monaurally. All fittings were validated by insertion gain measurements, and the immediate benefit was measured by means of the speech recognition score in background noise (SRSN; signal:noise ratio = 10 dB) without and with the HA. After a 6-week trial period a structured interview based on the International Outcome Inventory for Hearing Aids (IOI-HAs) was performed.&#x0D; Results: The results showed that the amplification of the HA deviated significantly from the NAL-R target at all frequencies, giving significantly more amplification at 500 and 1000 Hz despite maximum bass-cut, whenever relevant, and significantly less amplification as required at 2, 3 and 4 kHz. The median SRSN without HA was 48% (range 0-96%), which improved significantly to 80% (range 24-100%) with HA. The median individual difference in SRSN without and with HA was 20% (range 0-72%). The total IOI-HA score with the test HA was 4.1 (range 2.6-4.6), showing that it offered subjectively high satisfaction and reduction in limitations of activity.&#x0D; Conclusions: The low-cost HA: (i) provides benefit to the hearing-impaired person; (ii) offers poor amplification in the high frequencies; and (iii) gives subjective satisfaction similar to that for modern available HAs.&#x0D; Published courtesy of:Acta Otolaryngol. 2004; 124(4): 416-420