Real Ear Research Articles

Telessaúde: avaliação da eficácia da teleconsulta na programação e adaptação de aparelho de amplificação sonora individual

To evaluate teleconsultation's efficacy for hearing aid fitting. Fifty hearing impaired individuals with ages ranging from 39 to 88 years and mean audiometric thresholds between 30 and 68.75 dBHL participated in this study. Participants were divided into two groups (stratified randomization): control group (n=25), submitted to face-to-face procedures, and experimental group (n=25), submitted to synchronous teleconsultation with interactive video and remote applicative control. The hearing aids were programmed and verified (with microphone probe), and the subjects received instructions regarding use and care for the device. Time taken for the procedures was measured. Following the consultations, an evaluator (blind to the groups) applied the Hearing in Noise Test (HINT-Brazil). Approximately one month after consultations, the daily time of hearing aid use was verified, and the International Outcome Inventory for Hearing Aids (IOI-HA) was administered. A greater time for programming and verification and a smaller time for orientation were observed for the experimental group. No difference was found between groups for the total consultation time. The real ear measures' matching to their respective targets was similar for both groups. No difference was observed between groups for the HINT results (silence and noise), the daily amount of use of hearing aids in hours, and the IOI-HA scores. Teleconsultation is an efficient procedure for hearing aid programming, verification and fitting when face-to-face services are not available.

Effect of Active Noise Cancelling Earphones on Preferred Listening Level When Listening to Portable Music Players in Noisy Environments

Background and ObjectivesZZActive noise cancelling (ANC) is a technology that can reduce external noise by producing a signal that is similar to noise but different in that it has an opposite phase to noise. Nowadays ANC has become an important technology in the field of hearing aids, but many studies have not focused on the effect of ANC of earphones when listening to portable music players. In this study, we aimed to evaluate whether ANC earphones can effectively reduce external noise and lower the preferred listening level. Subjects and MethodZZThree different earphones (Ear-canal, On-the-ear, Covering-theear) were tested in three different noise environments. Nine participants were tested in 10 experiments. First, through the real ear measurement (REM) system, we evaluated the differences in sound pressure level when the ANC was either turned on or off. Second, we evaluated the effects of ANC on Preferred Listening Level (PLL) for participants listening to the same song with different earphones. Through the REM system, we evaluate the level of sound pressure level when participants controlled the volume and felt most comfortable with the volume level.

Audiologist-Driven Versus Patient-Driven Fine Tuning of Hearing Instruments

Two methods of fine tuning the initial settings of hearing aids were compared: An audiologist-driven approach--using real ear measurements and a patient-driven fine-tuning approach--using feedback from real-life situations. The patient-driven fine tuning was conducted by employing the Amplifit(®) II system using audiovideo clips. The audiologist-driven fine tuning was based on the NAL-NL1 prescription rule. Both settings were compared using the same hearing aids in two 6-week trial periods following a randomized blinded cross-over design. After each trial period, the settings were evaluated by insertion-gain measurements. Performance was evaluated by speech tests in quiet, in noise, and in time-reversed speech, presented at 0° and with spatially separated sound sources. Subjective results were evaluated using extensive questionnaires and audiovisual video clips. A total of 73 participants were included. On average, higher gain values were found for the audiologist-driven settings than for the patient-driven settings, especially at 1000 and 2000 Hz. Better objective performance was obtained for the audiologist-driven settings for speech perception in quiet and in time-reversed speech. This was supported by better scores on a number of subjective judgments and in the subjective ratings of video clips. The perception of loud sounds scored higher than when patient-driven, but the overall preference was in favor of the audiologist-driven settings for 67% of the participants.

Effect of Canal Depth on Sound Pressure Level Distribution in Human Bilateral Ears

This study was to measure the sound pressure level distribution by ear canal resonance in the human left and right external auditory canals (EAC). The gain for different stimulus frequencies was analyzed at four different measuring depths (0.5 cm, 1.0 cm, 1.5 cm and 2.0 cm) from the entrance of the ear canal bilaterally. Comparative evaluation showed that the gain for different stimulus frequencies at a depth of 2.0 cm was consistent with the results of Dillon’s study. In addition, the gain for the right EAC at 4000 Hz was larger than that of the left EAC by 1.2 dB at 0.5 cm, 1.8 dB at 1.0 cm, and 0.8 dB at 1.5 cm. This seems to suggest that gain at 4000 Hz is more affected by depth in the right EAC than in the left EAC. This study further found that the gain at the stimulus frequency of 4000 Hz was more affected by the depth than at 2000 Hz for the bilateral ear canals respectively. These gain differences between the right and left ears were statistically significant (p<0.05) at any of four measuring depths. The findings of this study may have an understanding of gain distribution to have implications for microphone placement of custom-made bilateral hearing aids (i.e. ITC or CIC) as these are placed at different depths within the ear canal. Keywords: Sound pressure level; Canal depth; Ear canal resonance; Real ear measurement; External auditory canal

Real ear measurement methods for open fit hearing aids: Modified pressure concurrent equalization (MPCE) versus modified pressure stored equalization (MPSE)

Objective: The aim of this study was to assess differences between real ear insertion gains (REIG) measured with the modified pressure concurrent equalization (MPCE) and modified pressure stored equalization (MPSE) methods for open fittings in a typical audiology patient population. Design: REIGs were compared for the two methods using a warble tone sweep at 65 dB SPL. The differences between the two methods at 0.25, 0.5, 1, 2, 3, 4 and 6 kHz were recorded. Study sample: Eighty-three ears of a consecutive sample of 48 candidates for open-fit hearing aids were included. Results: The mean difference between MPSE and MPCE REIGs was less than 1 dB at all frequencies. Analysis of variance showed that the main effect of method was not significant, and there was no significant interaction between method and frequency. Conclusions: The results for the MPSE and MPCE methods did not differ significantly for the patients with mild-to-moderate hearing losses tested here, for whom REIGs were generally less than 20 dB. Further research is needed to identify the REIG values at which the differences between MPCE and MPSE methods become clinically significant.

Measurement of Hearing Protection Devices Performance in the Workplace during Full-Shift Working Operations

The effectiveness of hearing protection devices (HPDs), when used in workplace conditions, has been shown over the years to be usually lower than the labeled values obtained under well-controlled laboratory conditions. Causes for such discrepancies have been listed and discussed by many authors. This study is an attempt to understand the issues in greater details and quantify some of these factors by looking at the performance of hearing protectors as a function of time during full work shift conditions. A non-invasive field microphone in the real ear (F-MIRE)-based method has been developed for measuring the effectiveness of different HPDs as a function of time in the workplace. Details of the test procedures, the equipment used, and the post-processing operations are presented and discussed. The methodology was developed in such a way that a complete time and frequency representation are possible. The system was used on a total of 24 workers in eight different companies. Work shifts of up to 9-h long were recorded. Various types of earmuffs and one type of molded earplugs were tested. Attenuation data reported as a function of time showed, for most workers tested, considerable fluctuations over entire work shift periods. Parts of these fluctuations are attributed to variations in the low-frequency content in the noise (in particular for earmuffs) as well as poor insertion and/or fitting of earplugs. Lower performances than laboratory-based ones were once again observed for most cases tested but also, important left and right ear differences were obtained for many individuals. When reported as a function of frequency, the attenuation results suggested that the few approximations used to relate the measurements to subjective real-ear-attenuation-at-threshold (REAT) data were realistic. The use of individualized attenuation data and performance ratings for HPDs as well as a good knowledge of the ambient noise in the workplace are key ingredients when evaluating the performance of hearing protectors in field conditions.

Accuracy and Reliability of a Real-Ear-to-Coupler Difference Measurement Procedure Implemented within a Behind-the-Ear Hearing Aid

Measurement of the real ear response of a fitted hearing aid allows matching of the frequency response to prescriptive targets, as well as comparison of the response to both threshold and loudness discomfort level (LDL). These processes are recommended procedures for hearing aid fittings. The real ear aided response (REAR) is often predicted based on the coupler response of the device, the real-ear-to-coupler difference (RECD), and the microphone location effect (MLE). Individualized measurement of the RECD tends to increase the accuracy of this prediction. A commercial hearing aid has been developed that measures the individual RECD and incorporates the data into the software-assisted fitting process. This study evaluated the test-retest reliability and predictive validity of this particular method for measuring the RECD. A repeated measures design was used to evaluate differences between subsequent measures of the RECD in the same ear, and prediction differences associated with using the RECD (and other information) to predict the REAR. Fifteen ears, on a convenience sample of ten adults (45-86 yr) and five children (6-15 yr) were tested. All participants were hearing aid users. Predicted and measured REARs were collected using normal clinical procedures, on an Audioscan Verifit VF-1 for two test signals/levels. Reliability, mean differences between predicted and measured REARs, and 95% confidence intervals of the prediction accuracy are reported. The RECD procedure had test-retest reliability within 2.5 dB for 14 out of 15 ears between 500 and 4000 Hz, and had predictive accuracy within 5 dB between 500 and 4000 Hz for 14 out of 15 ears. However, errors associated with earhook misalignment were discovered. Also, the RECD values measured using this hearing-aid-specific procedure differ somewhat from the normative data available from insert earphone RECDs. This procedure, when measured according to recommendations, provides a reasonably accurate prediction of the REAR. Functionally, this procedure does not replace the range of measures offered by modern real ear measurement systems. However, given the inaccuracy of software-assisted fittings without a measure of individual ear canal acoustics, use of this procedure may have the potential to improve the accuracy of fittings versus fittings completed without real ear measurement.

Comparison of a 3 dimension model versus a 2 dimension-axisymmetric finite element model of an occluded ear canal

Due to low cost and simplicity, earplugs are a widespread solution to prevent the problem of hearing loss in the workplace environment. In practice, earplugs often perceived are being uncomfortable and/or do not always perform as desired. The attenuation, based on a laboratory measurement, is often overestimated compared to in situ measurements. The use of a model of an occluded ear canal can help to build an individual measurement system of the attenuation and to develop an earplug with optimized attenuation. It is established that the unoccluded auditory canal can be approximated by a cylinder to predict the interior pressure field up to 6 kHz. A remaining question is whether this approximation holds true for an occluded ear. First, a simplified 2-D-axisymmetric finite element model of an ear canal coupled to a cylindrical earplug is developed. Special emphasis is on the coupling between the earplug and the lateral walls of the auditory canal. Second, a 3-D model of a real ear canal coupled to a cylindrical earplug is developed to examine the limits of the simplified model. Several assumptions about the deformation of the ear canal/earplug system are tested when comparing the sound attenuation provided by both models.

Measuring, rating, and comparing the real ear attenuation at threshold of four earplugs

The effect of training instruction, whether presented as the manufacturer's printed instructions, a short video training session, specific to the product, or as a one-on-one training session, was evaluated using four hearing protection devices with eight groups of subjects. The Howard Leight Fusion and Airsoft premolded earplugs and the Moldex PuraFit and EAR Classic foam earplugs were tested. Naive subjects were recruited and tested using three different forms of training: written, video, and individual training. The differences between group averages for A-weighted attenuation were not statistically significant when compared between the video or the written instruction conditions, regardless of presentation order. The experimenter- trained A-weighted attenuations were significantly greater than the written and video instruction for most of the protectors and groups. For each earplug, the noise reduction statistic for A-weighting (NRSA) and the associated confidence intervals were calculated for the 90th and 10th percentiles of protection. Across subject groups for each protector, the differences between NRSA ratings were found to be not statistically significant. Several comparisons evaluating the order of testing, the type of testing, and statistical tests of the performance across the groups are presented. [Portions of this work were supported by the U.S. EPA Interagency Agreement DW75921973-01-0.]

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.

Gain Affected by the Interior Shape of the Ear Canal

This study investigated the correlation of gain distribution and the interior shape of the human external ear canal. Cross-sectional study of gain measurement at the first bend and second bend. Chang Gung Memorial Hospital and Chang Gung University. There were 15 ears in patients aged between 20 and 30 years (8 men/7 women) with normal hearing and middle ears. Stimulus frequencies of 500, 1000, 2000, 3000, and 4000 Hz were based on the standard clinical hearing test. Measurements closer to the tympanic membrane and the positions at the first and second bends were confirmed by using otoscope. Real ear measurement to analyze the canal resonance in human external ears was adopted. This study found that gain at stimulus frequencies of 4000 Hz was affected by the interior shape of the ear canal (P < .005), particularly at the first and second bends, whereas gain was only affected by the length of the ear canal for stimulus frequencies of 2000 Hz (P < .005). This study found that gain was affected not only by the length of the external auditory canal (EAC) but also by the interior shape of the EAC significantly. The findings of this study may have potential clinical applications in canalplasty and congenital aural atresia surgery and may be used to guide surgeries that attempt to reshape the ear canal to achieve more desirable hearing outcomes.

Determinación de la atenuación en dispositivos auditivos tipo orejera aplicados en la protección, comunicación y entretenimiento con control activo de ruido

In this work a detailed analysis for determining the performance in noise reduction of three types of active noise cancellation hearing devices, which are applied to the protection, communication and entertainment is presented. This work was done using three standards available as references: a European (SS-EN 352-4), American (ANSI/ASA S12.42-2010) and the international one (ISO 4869-6). These standards provide all of the technical, theoretical, and practical specifications to evaluate the performance of hearing protectors. It will also be presented two of the methods commonly used to evaluate the performance of these devices: the objective method, microphone in real ear MIRE, and the subjective method, called real ear attenuation at threshold REAT. The operating principle of such devices is also discussed. Finally, a comparative analysis with previous works reported in the literature is presented.

Method and a Device for Real Ear Measurements

An adapter for coupling a probe tube for real ear measurements to a microphone of a hearing aid. The adapter comprises a sleeve adapted to be arranged around the housing of a hearing aid. The sleeve comprises a sound opening allowing sound to pass from the probe tube to the microphone. The adapter may form integral part of a device for real ear measurements, comprising a probe tube and an adapter for connecting the probe tube to a microphone, where the adapter comprises the sleeve adapted to be placed around the housing of a hearing aid said sleeve comprising a sound opening allowing sound to pass from the probe tube to the microphone. The device may be used in a method for performing real ear measurements comprising the steps of providing the device, fitting said device around the housing of the hearing aid so that the sound opening is placed over the built-in microphone of the hearing aid, placing the probe tube in the ear in such a way that a free end thereof presents an opening in the cavity between the earplug and the tympanic membrane, detecting the sound pressure from sounds produced by said hearing aid in said cavity using said microphone.

An analysis of hearing aid fittings in adults using cochlear implants and contralateral hearing aids

The objective of this study was to assess the appropriateness of hearing aid fittings within a sample of adult cochlear implant recipients who use a hearing aid in the contralateral ear (i.e., bimodal stimulation). The hearing aid gain was measured using real ear testing for 14 postlingually deaf English-speaking adults who use a cochlear implant in the contralateral ear. Unaided and aided audiometric testing assessed the degree of functional gain derived from hearing aid use. On average, the target to actual output level difference was within 10 dB only at frequencies of 750 Hz and 1,000 Hz. Only 1 of the 14 study participants had a hearing aid for which the majority of the tested frequencies were within 10 dB of the target gain. In addition, a greater amount of functional gain (i.e., the increase in unaided behavioral thresholds after amplification) was provided for lower frequencies than higher frequencies. Hearing aid settings in our sample were suboptimal and may be regarded as a contributing factor to the variability in bimodal benefit. Refining hearing aid fitting strategies tailored to the needs of the concurrent cochlear implant and hearing aid user is recommended.

Verification of In Situ Thresholds and Integrated Real-Ear Measurements

Accurate prescriptive gain results in a more accurate fit, lower return rate in hearing aids, and increased patient satisfaction. In situ threshold measurements can be used to determine required gain. The Widex Corporation uses an in situ threshold measurement strategy, called the Sensogram. Real-ear measurements determine if prescriptive gain targets have been achieved. Starkey Laboratories introduced an integrated real-ear measurement system in their hearing aids. To determine whether the responses obtained using the Widex Sensogram were equivalent to those obtained using current clinical threshold measurement methods. To determine the accuracy of the Starkey IREMS™ (Integrated Real Ear Measurement System) in measuring RECD (real-ear to coupler difference) values compared to a dedicated real-ear measurement system. A verification design was employed by comparing participant data measured from standard, benchmark equipment and procedures against new techniques offered by hearing-aid manufacturers. A total of 20 participants participated in this study. Ten participants with sensorineural hearing loss were recruited from the Ohio University Hearing, Speech, and Language Clinic participated in the first experiment. Ten participants with normal hearing were recruited from the student population at Ohio University participated in both experiments. The normal-hearing group had thresholds of 15 dB HL or better at the octave frequencies of 250-8000 Hz. The hearing-impaired group had thresholds of varying degrees and configurations with thresholds equal to or poorer than 25 dB HL three-frequency pure-tone average. The order of measurement method for both experiments was counterbalanced. In Experiment 1, thresholds obtained via the Widex Sensogram were compared to thresholds obtained for each participant using a clinical audiometer and ER-3A insert ear phones. In Experiment 2, RECD values obtained via the Starkey IREMS were compared to RECD values obtained via the Audioscan Verifit™. A repeated-measures analysis of variance (ANOVA) was used for statistical analysis, and a Fisher's LSD (least significant difference) was used as a post hoc analysis tool. A significant difference between Sensogram thresholds and conventional audiometric thresholds was found with the Sensogram method resulting in better threshold values at 0.5, 1.0, and 2.0 kHz for both groups. In Experiment 2, a significant difference between RECD values obtained by the Starkey IREMS and the Audioscan Verifit system was found with significant differences in RECD values found at 0.25, 0.5, 0.75, 1.5, 2.0, and 6.0 kHz. The Sensogram data differ significantly from traditional audiometry at several frequencies important for speech intelligibility. Real-ear measures are still required for verification of prescribed gain, however, calling into question any claims of shortened fitting time. The Starkey IREMS does perform real-ear measurements that vary significantly from benchmark equipment. These technologies represent a positive direction in prescribing accurate gain during hearing-aid fittings, but a stand-alone system is still the preferred method for real-ear measurements in hearing-aid fittings.

Listening Habits of iPod Users

To estimate real-environment iPod listening levels for listeners in 4 environments to gain insight into whether average listeners receive dosages exceeding occupational noise exposure guidelines as a result of their listening habits. The earbud outputs of iPods were connected directly into the inputs of a digital recorder to make recordings of listening levels. These recordings were used to estimate listening levels using reference recordings made in a real ear. Recordings were made in 4 environments with a wide range of background noises: (a) a library, (b) a student center, (c) busy streets, and (d) the subway. None of the 64 listeners were estimated to exceed allowable occupational dosages, with a maximum dose of 7.57% based on Occupational Safety and Health Administration (OSHA; 1998) methods and 10.83% based on National Institute for Occupational Safety and Health (NIOSH; 1998) methods. All of the listeners surveyed were exposed to dosages well below OSHA and NIOSH occupational regulations. Although this does not guarantee individual safety, the results do not support the widespread concern regarding the safety of common iPod usage. However, measurements made in this study agree with the finding that iPod output can exceed safe levels and further support recommendations to monitor and limit listening volume and listening duration.

Frequency-Lowering Hearing Aids: Verification Tools and Research Needs

Frequency-Lowering Hearing Aids: Verification Tools and Research Needs

Assess eardrum characteristics using standing wave technique.

It has been shown that eardrum reflection coefficients can be derived accurately up to 8 kHz based on standing wave patterns in the human ear canal, but not as reliably in higher frequencies [Lawton et al., J. Acoust. Soc. Am. 79, 1003 (1986)]. The primary purpose of this study is to investigate various factors affecting the accuracy of this type of measurements and extract important characteristics of ear canal and eardrum. In addition to reflection coefficients, eardrum impedance and the effect of loading on the eardrum are also examined. A model ear canal is constructed using a tube with variable loading conditions at one end. Measurements are taken along the center axis and contour of the tube when a stimulus is presented with frequency components up to 16 kHz, under both occluded and open situations. Results obtained from standing wave properties in the model ear canal are then compared to data acquired in real ear and in an ear simulator.

Earmuff noise attenuation by microphone in real ear technique.

When using a hearing protector at the workplace, it is necessary to quantify its noise attenuation by laboratory measurements. This paper aims at developing an objective methodology for measuring hearing protector noise attenuation of earmuff type using “microphone in real ear” (MIRE) method. The methodology uses the “insertion loss” (IL) as parameter, which is the difference between the sound pressure level with and without the hearing protector, using MIRE, and then calculating the hearing protector IL. The results for four different hearing protectors are compared with the subjective method “real-ear attenuation at threshold” (REAT). Factors such as physiological noise and bone conduction are quantified using the relation between MIRE and REAT method. Results are compared with values obtained from the literature.

A hearing protector model for predicting impulsive noise hazard.

Reduction in impulsive noise hearing hazard by earplugs and earmuffs is calculated with an electroacoustic lumped-parameter model of HPD attenuation using real ear attenuation at threshold (REAT) data. Energy flows into the occluded volume along three paths, each considered as a piston: (1) the rigid protector mass moving against the skin, (2) leakage at the support, and (3) transmission through the protector material (a second piston within the rigid piston). Circuit elements are adjusted so loss matches REAT data assuming path 1 is important at low, 2 at middle, and 3 at high REAT frequencies. Applying the model to 384 REAT data sets for ANSI S12.6 method B naive users gives statistical frequency distributions of occluded volume and leakage elements. For a given free-field impulsive noise, the model pressure predictions under the protector are compared to measurements on human and acoustical manikin ears to check validity of assumptions. The hearing hazards of the measured waveforms and the predicted waveforms are calculated with our previously developed auditory hazard analysis algorithm for humans ear model. The result is a cumulative frequency distribution of hazard based on user fit data useful in finding the best protector for a given impulsive noise.