Reliability and intersubject variability of the real ear unaided response

Listener Factors Explain Little Variability in Self-Adjusted Hearing Aid Gain

Self-adjustment of hearing aid gain can provide valuable information about the gain preferences of individual listeners, but these preferences are not well understood. Listeners with mild-to-moderate hearing loss used self-adjustment to select amplification gain and compression parameters in real time on a portable touch screen device while listening in quiet and noisy backgrounds. Adjustments to gain prescribed by the National Acoustics Laboratories' non-linear fitting procedure (NAL-NL2) showed large between-subject variability. Known listener characteristics (age, gender, hearing thresholds, hearing aid experience, acceptable noise level, and external ear characteristics) and listener engagement with the self-adjustment software were examined as potential predictors of this variability. Neither listener characteristics nor time spent adjusting gain were robust predictors of gain change from NAL-NL2. Listeners with less than 2 years of hearing aid experience and who also had better hearing thresholds tended to select less gain, relative to NAL-NL2, than experienced hearing aid users who had poorer thresholds. Listener factors explained no more than 10% of the between-subject variance in deviation from NAL-NL2, suggesting that modifying prescriptive fitting formulae based on the factors examined here would be unlikely to result in amplification parameters that are similar to user-customized settings. Self-adjustment typically took less than 3 min, indicating that listeners could use comparable technology without a substantial time commitment.

Development of Sound Field Audiometry System for Small Audiometric Booths and Comparison of Its Equivalence With Traditional System

OBJECTIVES

Sound field (SF) audiometry tests are usually conducted in audiometric booths measuring greater than 2×2 m in size. However, most private ENT clinics carry about 1×1-m-sized audiometric booths, making SF audiometry testing difficult to perform. The aims of this study were to develop an SF audiometry system for use in smaller audiometric booths and compare its performance with traditional system.

METHODS

The newly developed SF audiometry system can yield an SF signal at a distance of about 30 cm from the subject's ears. Its height can be adjusted according to the subject's head height. We compared SF hearing results between the new SF system and the traditional SF audiometry system in 20 adults with normal hearing (40 ears) and 24 adults with impaired hearing levels (38 ears) who wore hearing aids. Comparative parameters included warble tone audiometry threshold, a speech reception threshold (SRT), and a speech discrimination score (SDS). For statistical analysis, paired t-test was used. The equivalence of both SF systems was tested using two one-sided test (TOST) with a margin of 5 dB (normal hearing participants) and 10 dB (hearing aids wearing participants).

RESULTS

Among participants with normal hearing, warble tone hearing thresholds of 0.5, 1, 2, and 4 kHz, average values of these four frequencies, and SRT were similar between the two systems (all P>0.05). Participants with hearing aids showed similar warble tone threshold and SRT (P>0.05) in both systems except for threshold of 4 kHz (P=0.033). SDS was significantly higher in the newly developed system (P<0.05). TOST results showed equivalent SF audiometry results using either system.

CONCLUSION

Audiometric results of the newly developed SF audiometry system were equivalent to those of a traditional system. Therefore, the small SF audiometry system can be used at small audiometric booths present in most private ENT clinics.

A preliminary investigation into hearing aid fitting based on automated real-ear measurements integrated in the fitting software: test-retest reliability, matching accuracy and perceptual outcomes

OBJECTIVE

The recent integration of automated real-ear measurements (REM) in the fitting software facilitates the hearing aid fitting process. Such a fitting strategy, TargetMatch (TM), was evaluated. Test-retest reliability and matching accuracy were quantified, and compared to a REM-based fitting with manual adjustment. Also, it was investigated whether TM leads to better perceptual outcomes compared to a FirstFit (FF) approach, using software predictions only. Design and study sample: Ten hearing impaired participants were enrolled in a counterbalanced single-blinded cross-over study comparing TM and FF. Aided audibility, speech intelligibility and real-life benefits were assessed. Repeated measurements of both TM and REMs with manual adjustment were performed.

RESULTS

Compared to a REM-based fitting with manual adjustment, TM had higher test-retest reliability. Also, TM outperformed the other fitting strategies in terms of matching accuracy. Compared to a FF, improved aided audibility and real-life benefits were found. Speech intelligibility did not improve.

CONCLUSIONS

Preliminary data suggest that automated REMs increase the likelihood of meeting amplification targets compared with a FF. REMs integrated in the fitting software provide additional reliability and accuracy compared to traditional REMs. Findings need to be verified in a larger and more varied sample.

Extended bandwidth real-ear measurement accuracy and repeatability to 10 kHz

OBJECTIVE

Direct real-ear measurement to the 4-6 kHz range can be measured with suitable accuracy and repeatability. This study evaluates extended bandwidth measurement accuracy and repeatability using narrowband and wideband signal analysis.

DESIGN

White noise was measured in female ear canals at four insertion depths using one-third and one-twenty-fourth octave band averaging.

STUDY SAMPLE

Fourteen female adults with reported normal hearing and middle-ear function participated in the study.

RESULTS

Test-retest differences were within ±2 dB for typical frequency bandwidths at insertion depths administered in clinical practice, and for up to 8 kHz at the experimental 30 mm insertion depth. The 28 mm insertion depth was the best predictor of ear canal levels measured at the 30 mm insertion depth. There was no effect of signal analysis bandwidth on accuracy or repeatability.

CONCLUSIONS

Clinically feasible 28 mm probe tube insertions reliably measured up to 8 kHz and predicted intensities up to 10 kHz measured at the 30 mm insertion depth more accurately than did shallower insertion depths. Signal analysis bandwidth may not be an important clinical issue at least for one-third and one-twenty-fourth octave band analyses.

Verificação da prótese auditiva realizada face a face e via teleconsulta: medidas repetidas

OBJETIVO: avaliar as medidas repetidas da resposta de ressonância da orelha externa sem (REUR) e com uso de amplificação (REAR) e o ganho de inserção (REIG), realizados face a face e via teleconsulta. MÉTODO: estudo prospectivo longitudinal. Foram realizadas quatro repetições da REUR, REAR e REIG (com estímulo speech noise apresentado em 65 dB NPS e 0º azimute) em 19 orelhas de adultos ouvintes normais, via face a face (F) e teleconsulta síncrona por controle remoto de aplicativo (T) e vídeo interativo. O software Polycom PVX foi utilizado para compartilhamento e transmissão de áudio e vídeo. A conexão foi realizada via LAN (Local Area Network) USP na velocidade de 384 kbps Foi calculado o erro causal (Dalhberg) entre as quatro medidas para frequências de 250 a 8000 Hz. RESULTADOS: os erros casuais entre as medidas F e T foram muito semelhantes, sendo maiores nas frequências acima de 4 kHz. As diferenças e variações entre as medidas F e T estavam dentro da magnitude de variabilidade do procedimento de medidas com microfone sonda. CONCLUSÃO: as medidas com microfone sonda via teleconsulta fornece resultados confiáveis e similares aos obtidos pelo procedimento padrão.

Remote probe microphone measurement to verify hearing aid performance

We assessed the feasibility of obtaining probe microphone measurements of hearing aids at a distance. Face-to-face and remote probe microphone measurements were carried out in 60 hearing aid users (mean age 67 yrs) with uni- or bilateral hearing losses (105 ears tested). The participant and a facilitator were located in a room equipped with a probe microphone system interfaced to a PC. Desktop videoconferencing and application sharing was used to allow an audiologist in another room to instruct the facilitator and control the equipment via the LAN. There were significant correlations between face-to-face and remote real ear unaided response (REUR), aided response (REAR) and insertion gain (REIG) at seven discrete frequencies from 250 to 6000 Hz. Differences between face-to-face and remote responses were within the reported variability for probe microphone measurements themselves. The results show that remote probe microphone measurements are feasible and might improve the quality of public hearing aid services and professional training in Brazil.

Reconsidering the concept of the aided threshold for nonlinear hearing AIDS

The aided threshold (and functional gain) has been discussed in the context of linear hearing aids since the early 1960s. The use of nonlinear hearing aids, however, could change the meaningfulness of this verification tool because of their unique characteristics. The interpretation of the aided threshold (and functional gain) as it pertains to linear and nonlinear hearing aids is reviewed. Also discussed are the ideas of an optimal aided threshold, factors that may affect its magnitude, and a comparison between functional gain and insertion gain measures. Finally, how to improve the accuracy of the aided thresholds (and functional gain) through the use of in-situ unaided threshold measurements is discussed.

Changes in Hearing Sensitivity Following Portable Stereo System Use

Changes in hearing sensitivity following portable stereo system (PSS; Sony Walkman Model WM-AF605 with Sony Semiaural Headphones Model MDR-A21L) use were investigated. Test-retest differences (TRDs) in audiometric thresholds at eight frequencies (250, 500, 1000, 2000, 3000, 4000, 6000, & 8000 Hz) were obtained from 15 young adults before and after one hour of PSS exposure at their preferred listening levels.Values for the 95% confidence levels representing critical differences in test-retest auditory thresholds for the eight test frequencies were generated from a control group of 15 young adults. Experimental subjects' TRDs, when compared to the critical TRDs, failed to display a decrease in hearing sensitivity after one hour of PSS use. It is suggested that PSS use at preferred listening levels, following an exposure time of one hour, may not contribute to a significant impairment in hearing sensitivity.

External ear resonance as a screening technique in children with otitis media with effusion

External ear resonance can be quickly and accurately measured using real ear insertion gain equipment. It has been previously shown that external ear resonance characteristics are often altered by the presence of middle ear fluid. The external ear resonance characteristics of 84 children with a history of chronic middle ear disorder were determined. Results were compared to other audiological data and otological findings recorded during surgery. External ear resonance peak amplitude was significantly correlated with the presence or absence of middle ear fluid. It was found that peak amplitude of > or = 24 dB was associated with only 15% of dry ears and peak amplitude of < or = 22 dB associated with 79% of ears without fluid. The use of external ear resonance measures as a potential screening procedure is discussed.