Advantages of directional hearing aid microphones related to room acoustics.

In this study, two types of hearing aids were used. Both aids had the same frequency characteristics for frontal sound, but one employed an omnidirectional microphone and the other a directional microphone. The frequency characteristics of both hearing aids were measured for five azimuths on KEMAR and in situ in 12 normal-hearing subjects. For these subjects we also determined the speech reception threshold (SRT) with background noise in two rooms with different reverberation times. The direction of the speech stimuli was always frontal; the direction of the noise was varied. Additionally, directional hearing was measured with short noise bursts from eight loudspeakers surrounding the subject. In the less reverberant room, sounds coming from behind were less amplified by the hearing aid with the directional microphone than by the one with the omnidirectional microphone. In this room the monaural SRT values were largely determined by the level of the background noise. For the directional hearing aids there was an extra binaural advantage which depended on the direction of the background noise. Only for low-frequency noise bursts was directional hearing better with directional hearing aids. In the more reverberant room, no distinct differences between the frequency characteristics of the two hearing aid types were measured. However, a systematic difference between monaural SRT values measured through the two hearing aids was found. This difference was independent of noise azimuth. In conclusion, hearing aid(s) with a directional microphone showed no disadvantages and clear advantages under specific conditions.     

Directivity quantification in hearing aids: fitting and measurement effects

OBJECTIVE: To evaluate the impact of venting, microphone port orientation, and compression on the electroacoustically measured directivity of directional and omnidirectional behind-the-ear hearing aids. In addition, the average directivity provided across three brands of directional and omnidirectional behind-the-ear hearing aids was compared with that provided by the open ear. DESIGN: Three groups of hearing aids (four instruments in each group) representing three commercial models (a total of 12) were selected for electroacoustic evaluation of directivity. Polar directivity patterns were measured and directivity index was calculated across four different venting configurations, and for five different microphone port angles. All measurements were made for instruments in directional and omnidirectional modes. Single source traditional, and two-source modified front-to-back ratios were also measured with the hearing aids in linear and compression modes. RESULTS: The directivity provided by the open (Knowles Electronics Manikin for Acoustic Research) ear was superior to that of the omnidirectional hearing aids in this study. Although the directivity measured for directional hearing aids was significantly better than that of omnidirectional models, significant variability was measured both within and across the tested models both on average and at specific test frequencies. Both venting and microphone port orientation affected the measured directivity. Although compression reduced the magnitude of traditionally measured front-to-back ratios, no difference from linear amplification was noted using a modified methodology. CONCLUSIONS: The variation in the measured directivity both within and across the directional microphone hearing aid brands suggests that manufacturer's specification of directivity may not provide an accurate index of the actual performance of all individual instruments. The significant impact of venting and microphone port orientation on directivity indicate that these variables must be addressed when fitting directional hearing aids on hearing-impaired listeners. Modified front-to-back ratio results suggest that compression does not affect the directivity of hearing aids, if it is assumed that the signal of interest from one azimuth, and the competing signal from a different azimuth, occur at the same time.     

Effect of homolateral and contralateral routing of signals through Body-Worn hearing aids on the localization ability of Hearing-Impaired people

This investigation compared the localization abilities in the horizontal plane of 22 hearing-impaired adults (9 with symmetrical conductive and 13 with symmetrical sensorineural hearing impairment) whilst listening to speech through body-worn hearing aids in two different ways: (a) hearing-aid microphone placed on the same side as the stimulated ear (homolateral routing of signals); (b) hearing-aid microphone placed on the opposite side to the stimulated ear (contralateral routing of signals). It was found that the localization performances of all the subjects, especially when using binaural hearing aids, under homolateral routing of signals, were far superior to their respective localization performances achieved with contralateral routing of signals.

Résumé

Nous avons comparé la capacité de localiser des sons sur le plan horizontal chez 22 adultes atteints de surdité. Les sujets avaient des pertes bilatérales symétriques, soit surdités de transmission (9 sujets), soit surdités neuro-sensorielles (13 sujets). Les sujets devaient écouter des messages vocaux avec l'aide d'appareils de correction auditive portés sur le corps. Les appareils ont été utilisés de deux manières différentes: a) le microphone placé du méme côté que l'oreille stimulée (route homolatérale de stimulation); b) le microphone placé du côté opposé à l'oreille stimulée (route contralatérale de stimulation).

Nous avons constaté que la capacité de localiser des sons de tous les sujets, surtout quand ils portaient des appareils binauraux, était bien supérieure dans la condition de stimulation homolatérale aue dans la condition de stimulation controlatérale.     

Changes in sound-source localization for children with bilateral severe to profound hearing loss following simultaneous bilateral cochlear implantation

Background: Sound localization is a valuable skill that children can develop to some extent via bilateral cochlear implants (biCIs). However, little is known regarding the change that can be expected in sound-source localization accuracy (SLA) pre- and post-biCI for children with bilateral, severe-to-profound hearing impairment who spent their early years listening via bilateral hearing aids (biHAs). This study therefore aimed to prospectively assess SLA in a group of children before, and at one year after, receiving simultaneous biCIs.

Methods: Ten children aged 5–18 years were tested. SLA was assessed using loudspeakers positioned at ?60, ?30, 0, +30, and +60 degrees azimuth. Root mean square (RMS) errors and percentage correct scores were calculated. Changes in SLA were analysed via paired t-tests and potential relationships between hearing threshold levels (HTLs) and SLA via correlation analyses. Response distributions via biHAs and biCIs were examined via scatterplots.

Results: The mean within-subject changes in SLA were a significant improvement in RMS error of 11.9° (p?p?Conclusions: The findings of the present study demonstrate that simultaneous biCIs lead to improved sound localization in children with bilateral, severe to profound sensorineural hearing loss who previously used biHAs. SLA via biHAs or biCIs could not be predicted from children’s audiograms, and therefore should be measured directly.     

Use of a digital hearing aid with directional microphones in school-aged children

The efficacy of a digital hearing aid with a directional microphone was examined in a school-aged population. Twenty children (9 with a mild-to-moderately-severe hearing loss and 11 with a moderate-to-severe hearing loss) between 7 1/2 and 13 2/3 years of age wore the study hearing aids binaurally for 30 days prior to the evaluation. The testing protocol included speech recognition tests using the CID W-22 word lists presented at 72 dB SPL, 65 dB SPL, and 52 dB SPL (at 0 degrees azimuth) in the presence of a 65 dB SPL party noise (180 degrees azimuth). Subjective rating of hearing aid efficacy in the classroom was examined using the Listening Inventory For Education (LIFE) questionnaire. Parental impression on hearing aid efficacy was also collected at the end of the study. The results showed improved speech recognition in noise with the digital directional hearing aid at all presentation levels. Preference for the digital directional hearing aids over the subjects' own omnidirectional analog hearing aids was also seen on the LIFE questionnaire and parental impression. The degree of hearing loss did not seem to have affected the benefits offered by the digital directional hearing aids. These results were compared to results from other studies on the use of directional microphones in hearing aids.     

Speech polar plots for different directionality settings of SONNET cochlear implant processor

Objectives: The newest CI processor from MED-EL company, the SONNET, has two new directional microphone settings. Besides the Omnidirectional microphone mode, it has the possibility to switch to Natural or Adaptive directionality. Both new modes favour perception of sound coming from a front-facing direction compared to sounds from sources at alternate azimuths. Natural directionality mimics the pinna effect of the normal external ear.

Design: We undertook to verify the effect of these options in vivo by means of clinical audiological tests. Speech reception thresholds were successively measured for a variety of speech presentation azimuths while keeping the noise azimuths constant. Complete ‘Speech Reception Threshold (SRT)-Polar-Plots’ were obtained from these data for the Omnidirectional and Natural directionality modes of the SONNET. In addition, one ‘SRT-point’ was also measured in the ‘Adaptive’ mode for speech coming from 45° azimuth.

Study sample: A group of 13 adult CI recipients participated. Only one of these subjects had previous experience with the SONNET processor.

Results: Complete ‘SRT-Polar-Plots’ could be measured in Natural and Omnidirectional modes in CI recipients within an acceptable timeframe. The pinna-following directionality for Natural mode could be confirmed. Median SRT in noise for speech coming from the 45° azimuth speaker was ?5.6?dB SNR for Omnidirectional, ?9.1?dB SNR for Natural and ?12.8?dB SNR for Adaptive microphone. Natural and Adaptive significantly improved performance compared to Omnidirectional mode at this optimal azimuth of 45° with a median improvement in SRT of 3.5 and 7.2?dB respectively.

Conclusions: A novel audiological method, ‘SRT-Polar-Plot’, was developed and described. Significant directionality benefits for Natural and Adaptive mode were confirmed in vivo using this technique.     

听障儿童双耳双模式配戴的声源定位能力初探*

目的探讨双耳双模式配戴能否帮助听障儿童改善声源定位能力以及哪些因素可能影响双耳双模式声源定位优势的发挥。方法采用强迫二选一任务,比较16名听障儿童在不同助听模式及不同声源角度下的声源定位能力。结果声源位于90°/270°时,38%的被试体现出双耳双模式的声源定位优势;位于45°/315°时,优势比例下降到25%。进一步分析表明,人工耳蜗麦克风的位置以及术前双耳配戴助听器的经验与双耳双模式声源定位优势的发挥密切相关。结论声源定位能力是听障儿童日常生活中的难点,即使双耳双模式配戴,也仅在声源位于左右方时,比单侧耳蜗状态体现出一定优势,随着声源角度的减小,双耳强度差和时间差线索减弱,双耳双模式的声源定位优势也随之减小。人工耳蜗的麦克风须放置在正确位置,否则会影响声源定位能力。此外,术前助听器配戴经验可能会影响听障儿童利用双耳线索的能力。     

Advantages of Binaural Amplification to Acceptable Noise Level of Directional Hearing Aid Users

Objectives

The goal of the present study was to examine whether Acceptable Noise Levels (ANLs) would be lower (greater acceptance of noise) in binaural listening than in monaural listening condition and also whether meaningfulness of background speech noise would affect ANLs for directional microphone hearing aid users. In addition, any relationships between the individual binaural benefits on ANLs and the individuals'' demographic information were investigated.

Methods

Fourteen hearing aid users (mean age, 64 years) participated for experimental testing. For the ANL calculation, listeners'' most comfortable listening levels and background noise level were measured. Using Korean ANL material, ANLs of all participants were evaluated under monaural and binaural amplification with a counterbalanced order. The ANLs were also compared across five types of competing speech noises, consisting of 1- through 8-talker background speech maskers. Seven young normal-hearing listeners (mean age, 27 years) participated for the same measurements as a pilot testing.

Results

The results demonstrated that directional hearing aid users accepted more noise (lower ANLs) with binaural amplification than with monaural amplification, regardless of the type of competing speech. When the background speech noise became more meaningful, hearing-impaired listeners accepted less amount of noise (higher ANLs), revealing that ANL is dependent on the intelligibility of the competing speech. The individuals'' binaural advantages in ANLs were significantly greater for the listeners with longer experience of hearing aids, yet not related to their age or hearing thresholds.

Conclusion

Binaural directional microphone processing allowed hearing aid users to accept a greater amount of background noise, which may in turn improve listeners'' hearing aid success. Informational masking substantially influenced background noise acceptance. Given a significant association between ANLs and duration of hearing aid usage, ANL measurement can be useful for clinical counseling of binaural hearing aid candidates or unsuccessful users.     

Effect of homolateral and contralateral routing of signals through body-worn hearing aids on the localization ability of hearing-impaired people

This investigation compared the localization abilities in the horizontal plane of 22 hearing-impaired adults (9 with symmetrical conductive and 13 with symmetrical sensorineural hearing impairment) whilst listening to speech through body-worn hearing aids in two different ways: (a) hearing-aid microphone placed on the same side as the stimulated ear (homolateral routing of signals); (b) hearing aid microphone placed on the opposite side to the stimulated ear (contralateral routing of signals). It was found that the localization performances of all the subjects, especially when using binaural hearing aids, under homolateral routing of signals, were far superior to their respective localization performances achieved with contralateral routing of signals.     

A Comparative Study Of Physical Characteristics Of Hearing Aids On Microphone And Telecoil Inputs

The variations of sensitivity and frequency response of telecoil input on 32 commercially available body-type and behind-the-ear hearing aids were investigated. The differences in response between the microphone and the telecoil input were also examined. Findings indicate that (1) given aids have different sensitivity and frequency response for telecoil vs. microphone operation, (2) the telecoil, in general, provides a better low-frequency response than the microphone input, and (3) aids with similar responses on acoustic input may produce different responses on magnetic input. These findings further emphasize the importance of knowing the performance characteristics of the hearing aid operating on its telecoil input in order to avoid inappropriate hearing aid selection.     

Impact of compression and hearing aid style on directional hearing aid benefit and performance.

OBJECTIVE: To evaluate the impact of low-threshold compression and hearing aid style (in-the-ear [ITE] versus behind-the-ear [BTE]) on the directional benefit and performance of commercially available directional hearing aids. DESIGN: Forty-seven adult listeners with mild-to-moderate sensorineural hearing loss were fit bilaterally with one BTE and four different ITE hearing aids. Speech recognition performance was measured through the Connected Speech Test (CST) and Hearing in Noise Test (HINT) for a simulated noisy restaurant environment. RESULTS: For both the HINT and CST, speech recognition performance was significantly greater for subjects fit with directional in comparison with omnidirectional microphone hearing aids. Performance was significantly poorer for the BTE instrument in comparison with the ITE hearing aids when using omnidirectional microphones. No differences were found for directional benefit between compression and linear fitting schemes. CONCLUSIONS: No systematic relationship was found between the relative directional benefit and hearing aid style; however, the speech recognition performance of the subjects was somewhat predictable based on Directivity Index measures of the individual hearing aid models. The fact that compression did not interact significantly with microphone type agrees well with previously reported electroacoustic data.     

The effect of frequency-dependent microphone directionality on horizontal localization performance in hearing-aid users

Abstract

Frequency-dependent microphone directionality alters the spectral shape of sound as a function of arrival azimuth. The influence of this on horizontal-plane localization performance was investigated. Using a 360° loudspeaker array and five stimuli with different spectral characteristics, localization performance was measured on 21 hearing-impaired listeners when wearing no hearing aids and aided with no directionality, partial (from 1 and 2 kHz) directionality, and full directionality. The test schemes were also evaluated in everyday life. Without hearing aids, localization accuracy was significantly poorer than normative data. Due to inaudibility of high-frequency energy, front/back reversals were prominent. Front/back reversals remained prominent when aided with omnidirectional microphones. For stimuli with low-frequency emphasis, directionality had no further effect on localization. For stimuli with sufficient mid- and high-frequency information, full directionality had a small positive effect on front/back localization but a negative effect on left/right localization. Partial directionality further improved front/back localization and had no significant effect on left/right localization. The field test revealed no significant effects. The alternative spectral cues provided by frequency-dependent directionality improve front/back localization in hearing-aid users.

Sumario

La direccionalidad de un micrófono frecuencia-dependiente altera la configuración espectral del sonido como función del azimuth de llegada. Se investigó la influencia de esto en el desempeño para la localización en el plano horizontal. Usando un sistema de altoparlante 360° y cinco estímulos con diferentes características espectrales, se midió el desempeño para la localización en 21 hipoacúsicos, sin usar auxiliares auditivos y con el apoyo de no direccionalidad, de direccionalidad parcial (de 1 y 2 kHz) y con direccionalidad total. Los esquemas de la prueba también se evaluaron en la vida cotidiana. Sin auxiliares auditivos, la precisión para localizar fue significativamente más pobre que los datos normativos. Debido a la inaudibilidad de la energía de altas frecuencias, las inversiones frente/atrás fueron prominentes. Las inversiones frente/atrás permanecieron prominentes cuando hubo apoyo con micrófonos omnidireccionales. Para estímulos con énfasis en frecuencias graves, la direccionalidad no tuvo un efecto adicional en la localización. Con estímulos cuya información de frecuencias medias y altas fue suficiente, la direccionalidad total tuvo un pequeño efecto positivo para la localización frente/atrás, pero un efecto negativo en la localización izquierda/derecha. La direccionalidad parcial mejoró adicionalmente la localización frente/atrás pero no tuvo un efecto significativo en la localización izquierda/derecha. La prueba de campo no mostró efectos significativos. Las claves espectrales alternativas proporcionadas por la direccionalidad frecuencia-dependiente, mejoraron la localización frente/atrás en usuarios de auxiliares auditivos.     

Effects of CIC hearing aids on auditory localization by listeners with normal hearing.

An experiment was conducted to determine the effects of completely-in-the-canal (CIC) hearing aids on auditory localization performance. Six normal-hearing listeners localized a 750-ms broadband noise from loudspeakers ranging in azimuth from -180 degrees to +180 degrees and in elevation from -75 degrees to +90 degrees. Independent variables included the presence or absence of the hearing aid and the elevation of the source. Dependent measures included azimuth error, elevation error, and the percentage of trials resulting in a front-back confusion. The findings indicate a statistically significant decrement in localization acuity, both in azimuth and elevation, occasioned by the wearing of CIC hearing aids. However, the magnitude of this decrement was small compared to those typically caused by other ear-canal occlusions, such as earplugs, and would probably not engender mislocalization of real-world sounds.     

Randomized trial of amplification strategies

BACKGROUND: Little is known about quality of life after the use of specific types of hearing aids, so it is difficult to determine whether technologies such as programmable circuits and directional microphones are worth the added expense. OBJECTIVE: To compare the effectiveness of an assistive listening device, a nonprogrammable nondirectional microphone hearing aid, with that of a programmable directional microphone hearing aid against the absence of amplification. DESIGN: Randomized controlled trial. SETTING: Audiology clinic at the VA Puget Sound Health Care System, Seattle, Wash. PATIENTS: Sixty veterans with bilateral moderate to severe sensorineural hearing loss completed the trial. Half the veterans (n = 30) had hearing loss that the Veterans Affairs clinic determined was rated as "service connected," which meant that they were eligible for Veterans Affairs-issued hearing aids. INTERVENTION: Veterans with non-service-connected hearing loss, who were ineligible for Veterans Affairs-issued hearing aids, were randomly assigned to no amplification (control arm) or to receive an assistive listening device. Veterans with service-connected loss were randomly assigned to receive either the nonprogrammable hearing aid that is routinely issued ("conventional") or a programmable aid with a directional microphone ("programmable"). MAIN OUTCOME MEASURES: Hearing-related quality of life, self-rated communication ability, adherence to use, and willingness to pay for the amplification devices (measured 3 months after fitting). RESULTS: Clear distinctions were observed between all 4 arms. The mean improvement in hearing-related quality of life (Hearing Handicap Inventory for the Elderly) scores was small for control patients (2.2 points) and patients who received an assistive listening device (4.4 points), excellent for patients who received a conventional device (17.4 points), and substantial for patients who received a programmable device (31.1 points) (P<.001 by the analysis of variance test). Qualitative analyses of free-text diary entries, self-reported communication ability (Abbreviated Profile of Hearing Aid Benefit) scores, adherence to hearing aid use, and willingness to pay for replacement devices showed similar trends. CONCLUSIONS: A programmable hearing aid with a directional microphone had the highest level of effectiveness in the veteran population. A nonprogrammable hearing aid with an omnidirectional microphone was also effective compared with an assistive listening device or no amplification.     

Speech intelligibility in noisy environments with one- and two-microphone hearing aids

In this study speech intelligibility in background noise was evaluated with 10 binaural hearing-aid users for hearing aids with one omnidirectional microphone and a hearing aid with a two-microphone configuration (enabling an omnidirectional as well as a directional mode). Signal-to-noise ratio (SNR) measurements were carried out for three different types of background noise (speech-weighted noise, traffic noise and restaurant noise) and two kinds of speech material (bisyllabic word lists and sentences). The average SNR improvement of the directional microphone configuration relative to the omnidirectional one was 3.4 dB for noise presented from 90 degrees azimuth. This improvement was independent of the specific type of noise and speech material, indicating that one speech-in-noise condition may yield enough relevant information in the evaluation of directional microphones and speech understanding in noise.     

The psychophysical basis of monaural localization

Listeners were required to locate, monaurally, noise bursts emanating from the horizontal plane ipsilateral to the functioning ear. Loudspeakers were positioned from 0 through 180° azimuth, separated by 15°. Stimulus bandwidth was 1.0 kHz, and centered at 4.0–14.0 kHz in steps of 0.5 kHz. The location judgments were governed by the frequency composition of the stimuli, not by their place of origin. With a miniature microphone positioned at the entrance of the external ear canal, the relative amplification provided by the pinna was obtained for the stimuli employed in the localization tests. For each differently centered noise burst, that loudspeaker position re other positions which was associated with the greatest amplification of the stimulus was the one most likely to have been chosen as the source of that stimulus during the localization tests.     

How directional microphones affect speech recognition,listening effort and localisation for listeners with moderate-to-severe hearing loss

Objective: The purpose of this study was to evaluate the effects of directional microphone use on laboratory measures of sentence recognition, listening effort and localisation. An additional purpose of this study was to evaluate the effects of asymmetric directional microphone use on the same laboratory measures. Design: Three hearing aid conditions were evaluated: (1) bilateral omnidirectional microphones, (2) bilateral directional microphones and (3) asymmetric microphones (directional microphone for only one hearing aid). Sentence recognition performance was evaluated using a connected speech test. Listening effort was evaluated using a dual-task paradigm with a response time-based secondary task requiring word categorisation. Localisation was examined using a complex task requiring localisation and recall of speech originating from one of four loudspeakers in the horizontal plane (?60°, ?45°,?+45°,?+60°). Study sample: Eighteen adults (M?=?61.8 years) with symmetrical, moderate-to-severe hearing loss participated. Results: Performance on each task was analysed separately using a repeated measures analysis of variance. Results revealed directional benefits for sentence recognition and listening effort, but microphone setting did not affect localisation. Performance was equivalent with symmetric and asymmetric directional configurations. Conclusions: Bilateral and asymmetric directional microphone configurations equally improved sentence recognition and listening effort; neither affected localisation or recall.     

Frequency-modulation (FM) technology as a method for improving speech perception in noise for individuals with multiple sclerosis

Almost half of the population with multiple sclerosis (MS) complains of difficulty hearing, despite having essentially normal pure-tone thresholds. The purpose of the present investigation was to evaluate the effects of frequency-modulation (FM) technology utilization on speech perception in noise for adults with and without MS. Sentence material was presented at a constant level of 65 dBA Leq from a loudspeaker located at 0 degrees azimuth. The microphone of the FM transmitter was placed 7.5 cm from this loudspeaker. Multitalker babble was presented from four loudspeakers positioned at 45 degrees, 135 degrees, 225 degrees, and 315 degrees azimuths. The starting presentation level for the babble was 55 dBA Leq, The level of the noise was increased systematically in 1 dB steps until the subject obtained 0% key words correct on the IEEE (Institute for Electrical and Electronic Engineers) sentences. Test results revealed significant differences between the unaided and aided conditions at several signal-to-noise ratios.     

Estimated variability of real-ear insertion response (REIR) due to loudspeaker type and placement

The real-ear insertion response (REIR) of a hearing aid is estimated as the difference between the aided response and the unaided response in the ear canal. Changes in the position of the loudspeaker relative to the head, between the two measurements, may reduce the accuracy of the estimate. The spatial variability of the sound field at distances close to the loudspeaker is less for a ‘flat-panel’ loudspeaker than for a conventional cone loudspeaker; the panel might thus lead to a reduced influence of loudspeaker position. To assess this, we measured the real-ear unaided response (REUR) as each of three loudspeakers (two cone type and one panel) was moved in a threedimensional space centred at either 0° or 45° azimuth, at a distance of 50 cm from a KEMAR manikin. Contrary to our expectation, the variability of the REUR was larger for the panel than for the cone loudspeakers. The REUR varied less with position for the 0° than for the 45° azimuth. The variability of the REUR decreased with increasing distance of the loudspeaker from KEMAR. We tentatively suggest that loudspeaker-to-client distances of 40–50 cm should be used and that a 0° azimuth is preferable.     

The effect of multi-channel wide dynamic range compression, noise reduction, and the directional microphone on horizontal localization performance in hearing aid wearers

This study examined the effect that signal processing strategies used in modern hearing aids, such as multi-channel WDRC, noise reduction, and directional microphones have on interaural difference cues and horizontal localization performance relative to linear, time-invariant amplification. Twelve participants were bilaterally fitted with BTE devices. Horizontal localization testing using a 360 degrees loudspeaker array and broadband pulsed pink noise was performed two weeks, and two months, post-fitting. The effect of noise reduction was measured with a constant noise present at 80 degrees azimuth. Data were analysed independently in the left/right and front/back dimension and showed that of the three signal processing strategies, directional microphones had the most significant effect on horizontal localization performance and over time. Specifically, a cardioid microphone could decrease front/back errors over time, whereas left/right errors increased when different microphones were fitted to left and right ears. Front/back confusions were generally prominent. Objective measurements of interaural differences on KEMAR explained significant shifts in left/right errors. In conclusion, there is scope for improving the sense of localization in hearing aid users.