A Continuously Worn Dual Temperature Sensor System for Accurate Monitoring of Core Body Temperature from the Ear Canal

The objective of this work was to develop a temperature sensor system that accurately measures core body temperature from an ear-worn device. Two digital temperature sensors were embedded in a hearing aid shell along the thermal gradient of the ear canal to form a linear heat balance relationship. This relationship was used to determine best fit parameters for estimating body temperature. The predicted body temperatures resulted in intersubject limits of agreement (LOA) of ±0.49 °C over a range of physiologic and ambient temperatures without calibration. The newly developed hearing aid-based temperature sensor system can estimate core body temperature at an accuracy level equal to or better than many devices currently on the market. An accurate, continuously worn, temperature monitoring and tracking device may help provide early detection of illnesses, which could prove especially beneficial during pandemics and in the elderly demographic of hearing aid wearers.

Improving Speech Understanding and Monitoring Health with Hearing Aids Using Artificial Intelligence and Embedded Sensors

This article details ways that machine learning and artificial intelligence technologies are being integrated in modern hearing aids to improve speech understanding in background noise and provide a gateway to overall health and wellness. Discussion focuses on how Starkey incorporates automatic and user-driven optimization of speech intelligibility with onboard hearing aid signal processing and machine learning algorithms, smartphone-based deep neural network processing, and wireless hearing aid accessories. The article will conclude with a review of health and wellness tracking capabilities that are enabled by embedded sensors and artificial intelligence.

Autoimmune Inner Ear Disease: Diagnostic and Therapeutic Approaches in a Multidisciplinary Setting

Autoimmune Inner Ear Disease (AIED) is a clinical syndrome of uncertain pathogenesis. It is associated with bilateral rapidly progressive hearing loss. The hearing loss may be associated with vestibular symptoms. Autoimmunity has been proposed as the pathogenesis of this sort of hearing loss, although the mechanism of the disease is poorly understood. It is well accepted that the endolymphatic sac is an immunocompetent organ and circulating autoantibodies against inner ear antigens have been reported, as have viral antigens in the endolymph, although the sensitivity, specificity, and roles of those antibodies in a disease process are poorly defined.

We will describe the clinical aspects of the disease, the histopathology, the immunologic indicators, the types of presentation, both from the audiologic and vestibular point of view, clinical trials for treatment and the follow-up. One of our conclusions is that many of these patients respond favorably to the treatment Methotrexate.

The Future of Private Practice in Audiology

Although private practice in audiology has evolved during the past 40 years, hearing aids have remained as a central component to success. This article will discuss present and future trends for the next 40 years, including parallels to other professions and the need to innovate beyond technology.

A clinical protocol for predicting outcomes with an implantable prosthetic device (Baha) in patients with single-sided deafness

BACKGROUND

The Baha implant is increasingly becoming a common form of treatment for individuals with single-sided deafness (SSD). However, evidence-based guidelines for determining candidacy in these patients are not yet established.

PURPOSE

The purpose of this study was to investigate the clinical utility of speech-in-noise testing as a part of the preoperative evaluation of the Baha device in patients with SSD.

RESEARCH DESIGN

The study design was a prospective cohort of 24 English-speaking adults comparing preoperative results on speech-in-noise measures using the Baha Cordelle II headband stimulator to postoperative results using the patient's external Baha processor.

INTERVENTION

Outcome measures included signal-to-noise ratio (SNR) loss as measured by the QuickSIN™ and scores of self-reported disability questionnaires.

RESULTS

Wilcoxon signed-rank test resulted in no significant difference between the preoperative and postoperative methods for measuring benefit on listening in noise tasks. Passing Bablok regression analysis showed the preoperative and postoperative results to be statistically equivalent, which suggests that postoperative results can be predicted during preoperative testing. Wilcoxon signed-rank test showed significant improvements in self-reported disability postoperatively.

CONCLUSIONS

The results support the use of speech-in-noise measures as an accurate predictor of overall benefit in patients with SSD prior to implantation.

Secondhand smoke exposure and the risk of hearing loss

Hearing loss has been associated with tobacco smoking, but its relationship with secondhand smoke is not known. We sought to investigate the association between secondhand smoke exposure and hearing loss in a nationally representative sample of adults. The National Health and Nutrition Examination Survey (NHANES), a nationally representative cross-sectional dataset, was utilised to investigate the association between secondhand smoke exposure and hearing loss. Data collected from non-smoking participants aged 20-69 years were included in the analysis if they had completed audiometric testing, had a valid serum continue value, and provided complete smoking, medical co-morbidity and noise exposure histories (N=3307). Hearing loss was assessed from averaged pure-tone thresholds over low- or mid-frequencies (500, 1000 and 2000 Hz) and high-frequencies (3000, 4000, 6000 and 8000 Hz), and was defined as mild or greater severity (pure-tone average in excess of 25 dB HL). Second-Hand Smoke (SHS) exposure was significantly associated with increased risk of hearing loss for low-/mid-frequencies (adjusted OR=1.14; 95% CI 1.02-1.28 for never smokers and 1.30; 1.10-1.54 for former smokers) and high-frequencies (1.40; 1.22-1.81 for former smokers), after controlling for potential confounders. Findings from the present analysis indicate that SHS exposure is associated with hearing loss in non-smoking adults.

Nonlinear hearing AIDS and verification of fitting targets

This paper addresses the issue of initial verification of hearing aid gain and output for nonlinear hearing aids. Specifically, "urban legend" has it that nonlinear hearing aids with digital noise reduction circuitry may not be accurately measured using functional gain and/or probe microphone measures. Discussed are the advantages and disadvantages of both measurement strategies, and how they may be used to "acoustically match" hearing aids to individual patients. An evaluation protocol that employs both optimal aided thresholds and probe microphone measurements to assess gain, output, and audibility in hearing-impaired patients.

Autoimmune inner ear disease: diagnostic and therapeutic approaches in a multidisciplinary setting

Autoimmune Inner Ear Disease (AIED) is a clinical syndrome of uncertain pathogenesis. It is associated with bilateral rapidly progressive hearing loss. The hearing loss may be associated with vestibular symptoms. Autoimmunity has been proposed as the pathogenesis of this sort of hearing loss, although the mechanism of the disease is poorly understood. It is well accepted that the endolymphatic sac is an immunocompetent organ and circulating autoantibodies against inner ear antigens have been reported, as have viral antigens in the endolymph, although the sensitivity, specificity, and roles of those antibodies in a disease process are poorly defined. We will describe the clinical aspects of the disease, the histopathology, the immunologic indicators, the types of presentation, both from the audiologic and vestibular point of view, clinical trials for treatment and the follow-up. One of our conclusions is that many of these patients respond favorably to the treatment Methotrexate.

The utility of positron emission tomography in the evaluation of autoimmune hearing loss

OBJECTIVE

To evaluate positron emission tomography as an imaging tool in the diagnosis, evaluation, and management of autoimmune inner ear disease.

BACKGROUND

Autoimmune inner ear disease is a form of cochleovestibular disease associated with variable hearing loss and vertigo for which no reliable diagnostic tests are available.

METHODS

Pilot study of 10 patients with autoimmune inner ear disease and 5 sex-matched and age-matched control subjects without any history of autoimmune inner ear disease, who underwent limited positron emission tomography of the inner ear. Five patients with new or active autoimmune inner ear disease underwent serial positron emission tomography before and after 4 to 6 weeks of a high-dose tapering course of prednisone. The subjects had cranial magnetic resonance imagining, audiometric and vestibular studies, and heat-shock protein (HSP-70) measurements. Reading of the positron emission tomography scans was blinded.

RESULTS

Positron emission tomography was normal in 4 of 5 normal control subjects and abnormal in 1 with normal audiometric and vestibular studies and positive HSP-70. Of patients with established and stable autoimmune inner ear disease, 4 of 5 had no positron emission tomography abnormalities and negative HSP-70, and the one with abnormal positron emission tomography shortly thereafter manifested clinically active disease. Of the 5 patients with active autoimmune inner ear disease monitored serially, 4 had an initial abnormal positron emission tomography in at least one ear, which became normal in all but 1 patient after therapy. HSP-70 correlated with disease activity. Only 1 patient with clinically active autoimmune inner ear disease had a normal positron emission tomography before and after therapy (the HSP-70 was positive before therapy and negative after the therapy).

CONCLUSIONS

Positron emission tomography, especially when combined with HSP-70 determination, may be a useful technique for assessing disease in patients with autoimmune inner ear disease.

Open trial of methotrexate as treatment for autoimmune hearing loss

OBJECTIVE

To assess the efficacy of low-dose methotrexate (MTX) administered for the treatment of autoimmune hearing loss.

METHODS

This was a prospective, 12-month, open-label study of 17 patients with refractory autoimmune hearing loss. All patients had ongoing episodic worsening of hearing in one or both ears prior to enrollment despite traditional medical therapy. The MTX dose was 7.5-25 mg/week. Hearing loss and vertigo were evaluated at baseline and at completion of the study. Hearing improvement was defined as an improvement in pure tone threshold (PT) average of >10 dB or an increase in speech discrimination (SD) of >15%; worsening was defined as a decrease of >10 dB in PT or a decrease of >15% in SD in at least one ear.

RESULTS

MTX was well tolerated. Among patients with Meniere's disease, 5 of 9 had improvement or resolution of vertigo. Equilibrium improved in all 3 patients with Cogan's syndrome and improved in 2 out of 3 patients with idiopathic hearing loss and this symptom. According to the parameters defined above, hearing improved in 11 patients (65%), was unchanged in 4 patients (23%), and worsened in 2 patients (12%).

CONCLUSION

Long-term low-dose MTX therapy may be a useful therapy for at least some patients who have hearing loss with a presumptively autoimmune-mediated component that is refractory to traditional therapies.

Open trial of methotrexate as treatment for autoimmune hearing loss

OBJECTIVE

To assess the efficacy of low-dose methotrexate (MTX) administered for the treatment of autoimmune hearing loss.

METHODS

This was a prospective, 12-month, open-label study of 17 patients with refractory autoimmune hearing loss. All patients had ongoing episodic worsening of hearing in one or both ears prior to enrollment despite traditional medical therapy. The MTX dose was 7.5-25 mg/week. Hearing loss and vertigo were evaluated at baseline and at completion of the study. Hearing improvement was defined as an improvement in pure tone threshold (PT) average of >10 dB or an increase in speech discrimination (SD) of >15%; worsening was defined as a decrease of >10 dB in PT or a decrease of >15% in SD in at least one ear.

RESULTS

MTX was well tolerated. Among patients with Meniere's disease, 5 of 9 had improvement or resolution of vertigo. Equilibrium improved in all 3 patients with Cogan's syndrome and improved in 2 out of 3 patients with idiopathic hearing loss and this symptom. According to the parameters defined above, hearing improved in 11 patients (65%), was unchanged in 4 patients (23%), and worsened in 2 patients (12%).

CONCLUSION

Long-term low-dose MTX therapy may be a useful therapy for at least some patients who have hearing loss with a presumptively autoimmune-mediated component that is refractory to traditional therapies.

Development of the Three-Clinic Hearing Aid Selection Profile (HASP)

The Three-Clinic Hearing Aid Selection Profile (HASP) was developed to assess a patient's beliefs about a number of basic considerations felt to be critical to the hearing aid selection (HAS) process. These characteristics are felt to be key to the acceptance of amplification and include motivation, expectations, cost of goods and services, appearance (cosmesis), attitudes about technology, physical function/limitations, communication needs, and lifestyle. The results of the first investigation suggest that we have been successful in developing a 40–item metric with adequate internal consistency reliability that assesses the aforementioned characteristics. Second, results of the administration of this tool to a large group of individuals indicated that (1) age impacted scores on the Technology, Physical Function, and Communicative Needs subscales; (2) gender impacted scores on the Motivation, Expectation, Technology, Communicative Needs, and Appearance subscales; (3) previous hearing aid use affected scores on the Motivation subscale; (4) level of education impacted scores on the Physical Function and Lifestyle subscales; and (5) self-perceived hearing handicap had an effect on Motivation and Communicative Needs subscale scores. Percentile data collected from this subject sample are presented as a benchmark against which to evaluate responses from individual patients. Case studies are presented to illustrate the potential clinical utility of this device.

Abbreviations: ANOVA = analysis of variance, CIC = completely in the canal, COSI = Client Oriented Scale of Improvement, DSP = digital signal processing, HAS = hearing aid selection, HASP = Hearing Aid Selection Profile, HHIA = Hearing Handicap Inventory for Adults, HHIE = Hearing Handicap Inventory for the Elderly

Development of the Three-Clinic Hearing Aid Selection Profile (HASP)

The Three-Clinic Hearing Aid Selection Profile (HASP) was developed to assess a patient's beliefs about a number of basic considerations felt to be critical to the hearing aid selection (HAS) process. These characteristics are felt to be key to the acceptance of amplification and include motivation, expectations, cost of goods and services, appearance (cosmesis), attitudes about technology, physical function/limitations, communication needs, and lifestyle. The results of the first investigation suggest that we have been successful in developing a 40-item metric with adequate internal consistency reliability that assesses the aforementioned characteristics. Second, results of the administration of this tool to a large group of individuals indicated that (1) age impacted scores on the Technology, Physical Function, and Communicative Needs subscales; (2) gender impacted scores on the Motivation, Expectation, Technology, Communicative Needs, and Appearance subscales; (3) previous hearing aid use affected scores on the Motivation subscale; (4) level of education impacted scores on the Physical Function and Lifestyle subscales; and (5) self-perceived hearing handicap had an effect on Motivation and Communicative Needs subscale scores. Percentile data collected from this subject sample are presented as a benchmark against which to evaluate responses from individual patients. Case studies are presented to illustrate the potential clinical utility of this device.

Use of methotrexate for autoimmune hearing loss

To assess the efficacy of low-dose methotrexate (MTX) given long-term for the treatment of autoimmune hearing loss, we performed a prospective open-label study of 11 patients with treatment-refractory autoimmune hearing loss. All patients had ongoing episodic worsening of hearing in 1 or both ears before enrollment despite traditional medical therapy. The MTX dose was 7.5 to 17.5 mg/wk. Hearing loss and vertigo were evaluated at baseline and at completion of the study. Hearing improvement was defined as an improvement in the pure tone threshold (PT) average of >10 dB or an increase in speech discrimination (SD) of >15%, whereas worsening was defined as a worsening of >10 dB in PT or a decrease of >15% in SD in at least 1 ear. The MTX was well tolerated. Among the 6 patients with Meniere's disease. 4 had improvement or resolution of vertigo, while 2 had no improvement. Disequilibrium improved in all 3 patients with Cogan's syndrome. According to the parameters defined above, hearing improved in 9 patients (82%), was unchanged in 1 patient (9%), and worsened in 1 patient (9%). Long-term low-dose MTX therapy may be a useful therapy for some patients who have hearing loss with a presumptively autoimmune-mediated component that is refractory to traditional therapies.

Audiometric findings in patients with acoustic neuroma

OBJECTIVE

Hearing loss remains the most common symptom associated with acoustic neuroma. This study documents the audiometric findings from 721 acoustic neuroma procedures.

STUDY DESIGN

This was a retrospective study. The preoperative audiometric data were compiled and were analyzed by patient age, gender, tumor size, time of surgery, and neurofibromatosis Type 2 (NF 2). Postoperative audiometric data were arranged and compiled in the same way. The hearing classification proposed by the AAO-HNS was applied to all preoperative and postoperative cases.

SETTING

Tertiary referral center.

PATIENTS

Surgically confirmed acoustic neuroma patients who had not previously received surgical or radiosurgical therapy. Patients underwent surgery by the retrosigmoid approach.

INTERVENTION

Surgical removal of an acoustic neuroma. MAIN OUTCOME RESULT: Provision of pure tone and speech data from a group of acoustic neuroma patients, including application of the recently introduced and accepted AAO-HNS hearing classification system.

RESULTS

Preoperative audiometric data were obtained from 694 of 721 patients (96%), of whom 619 had measurable hearing. Postoperative audiometry was performed on 606 patients; 152 had usable data. The combined preoperative audiometric data revealed a high frequency sensorineural hearing loss. Word recognition was servicable. The postoperative pure tones and word recognition scores were worse than preoperative scores. Age, gender, tumor size, and time of surgery had some impact on the preoperative hearing and the postoperative result; NF 2 did not.

CONCLUSIONS

The study confirms that hearing alteration is almost universal in acoustic neuroma patients. Hearing preservation is possible in a significant number of cases; however, the postoperative auditory function tends to be worse.

Hearing loss and phacoemulsification

PURPOSE

To determine the acoustic spectra of currently used phacoemulsification units and to contrast phacoemulsification-generated acoustic spectra with representative audiograms of common types of sensorineural hearing loss.

SETTING

Mayo Clinic, Rochester, Minnesota, USA.

METHODS

The acoustic spectra of 3 phacoemulsification systems (Alcon Series 20,000 Legacy, Storz Millennium, and AMO Diplomax) were recorded in an acoustically soundproofed room using a Roland VS-880 Digital Studio Workstation and analyzed with a Hewlett-Packard 35660A Dynamic Signal Analyzer.

RESULTS

Phacoemulsification handpiece-generated harmonic overtones produced during ultrasound mode (6.0, 12.0, and 18.8 kHz for the 20,000 Legacy and Diplomax; 7.0 and 14.2 kHz for the Millennium) were outside the range of minimal decibel loss in individuals with hearing loss. Supplemental, low-frequency, console-generated tones produced during ultrasound mode (0.4 to 2.0 kHz for the Diplomax; 0. 1 to 1.5 kHz for the Millennium) were within the range of minimal decibel loss in individuals with hearing loss.

CONCLUSION

Phacoemulsification systems with console-generated, low-frequency tones were audible to ophthalmologists with common types of sensorineural hearing loss.

Comparing the performance of the Widex SENSO digital hearing aid with analog hearing aids

Differences in performance were evaluated between the Widex SENSO and several analog hearing aids currently worn by 50 hearing-impaired subjects. Subjects were initially fit with the SENSO using the manufacturer's recommended procedure. After wearing the hearing aids for 1 week, the adjustable parameters were fine-tuned based on subjective comments. Differences in performance between the SENSO and the subjects' current hearing aids were assessed using the Speech Perception in Noise administered at overall levels of 50, 65, and 80 dB SPL; the Hearing in Noise Test in which the background noise was presented at 50, 65, and 80 dBA; the Abbreviated Profile of Hearing Aid Benefit; and two questionnaires relating to overall preference between the SENSO and the subjects' current hearing aids.

Effect of Temperature Elevation on Rabbit Cochlear Function as Measured by Distortion-Product Otoacoustic Emissions

Low-intensity laser stapedotomy has been shown to produce temperature elevations of 3° to 4° C within the cochlea. This study investigates the effect of temperature elevations in this range on cochlear outer hair cell function by use of distortion-product otoacoustic emissions in rabbits. Using esophageal temperature monitoring, we compared 2f1-f2 distortion-product otoacoustic emissions over a range of frequencies (1806 to 8691 Hz) at rabbit normothermia, normothermia plus 3° C, and normothermia after passive cooling. Cochlear temperature was found to exceed changes in esophageal temperature by as much as 1.2° C. We found that a maximum of 3° C elevation in esophageal temperature did not permanently impair outer hair cell function in the rabbit cochlea. Results of this study suggest that moderate changes in cochlear temperature, such as those produced by low-intensity CO2 and holmium-yttrium aluminum garnet lasers, may not produce irreversible thermal damage to the cochlear outer hair cells.

Effect of temperature elevation on rabbit cochlear function as measured by distortion-product otoacoustic emissions

Low-intensity laser stapedotomy has been shown to produce temperature elevations of 3 degrees to 4 degrees C within the cochlea. This study investigates the effect of temperature elevations in this range on cochlear outer hair cell function by use of distortion-product otoacoustic emissions in rabbits. Using esophageal temperature monitoring, we compared 2f1-f2 distortion-product otoacoustic emissions over a range of frequencies (1806 to 8691 Hz) at rabbit normothermia, normothermia plus 3 degrees C, and normothermia after passive cooling. Cochlear temperature was found to exceed changes in esophageal temperature by as much as 1.2 degrees C. We found that a maximum of 3 degrees C elevation in esophageal temperature did not permanently impair outer hair cell function in the rabbit cochlea. Results of this study suggest that moderate changes in cochlear temperature, such as those produced by low-intensity CO2 and holmium-yttrium aluminum garnet lasers, may not produce irreversible thermal damage to the cochlear outer hair cells.

Recognition of speech in noise with hearing aids using dual microphones

Fifty subjects with mild to moderately severe sensorineural hearing loss and prior experience with amplification were evaluated at two sites (25 subjects at each site). Speech recognition in noise scores were measured using the Hearing in Noise Test (HINT) for each subject while wearing binaural behind-the-ear hearing aids allowing switching between two fitting algorithms ("basic" and "party") and two microphone conditions (single microphone omnidirectional and dual-microphone directional). Results revealed an average improvement in signal-to-noise ration (SNR) of 7.4 to 8.5 dB at the two sites for the directional conditions in comparison to the omnidirectional conditions. No significant improvement in SNR was measured between the two fitting algorithms. In addition, the Profile of Hearing Aid Benefit (PHAB) (Site I) and the Abbreviated Profile of Hearing Aid Benefit (APHAB) (Site II) were administered. Results revealed that the benefit scores for background noise and reduced cues (Site I) and background noise and aversiveness of sounds (Site II) were significantly higher than those reported in the established norms. Finally, 76 percent of the subjects of Site I reported that the experimental hearing aids provided "significantly better" or "better" performance than their current hearing aids.

Hearing loss as occupational hazard

Is the technology any better today than it has been? Without question, there have been improvements in the past five years that enable hearing aids to better fit noise-induced hearing losses. The bottom line, however, is that hearing aids are still a prosthesis, not a solution to the problem of hearing loss. The final decision of whether to purchase a hearing aid or not is dependent upon many factors that should be discussed with your health care professional. Hearing aids have improved a lot in recent years, but their function still boils down to two important tasks: selectively amplifying sounds not heard by the individual, and preventing loud sounds from reaching uncomfortable levels.

Noise reduction with FM systems in FM/EM mode

Commercially available noise reduction hearing aids have failed to deliver improved speech recognition in noise over properly fit conventional devices under typical listening conditions (Fabry & Van Tasell, 1990; Gabrielsson, Schenkman, & Hagerman, 1988; Tyler & Kuk, 1989; Van Tasell, Larsen, & Fabry, 1988). The primary factor related to this finding is that speech and noise are mixed at the input of a single microphone; spectral changes are applied equally to both speech and noise, and the signal-to-noise ratio remains unchanged from unprocessed conditions. The purpose of this study was to evaluate a prototype frequency-modulated (FM) auditory trainer that allowed use of a remote FM microphone and/or an ear level environmental microphone (EM). For each of five subjects with moderate to severe sensorineural hearing loss, the frequency response of the EM was configured either to match that of the FM response, or to provide a high-pass filter characteristic similar to a noise reduction hearing aid. Speech recognition threshold (SRT) testing noise was measured for five test conditions: 1) FM only; 2) EM only with high-pass filter response (EM-HP); 3) EM only with "standard" response (EM-S) matched to FM; 4) FM/EM-HP combined mode; and 5) FM/EM-S mode. Results averaged across subjects indicated that SRTs for the FM only condition were 9 to 10 dB better than those for either EM only condition; data from the combined FM/EM-HP mode averaged 4 dB better than for FM/EM-S conditions.

Clinical and communication access through amplification for a medical student with severe hearing loss: case report

This case report focuses on the communication difficulties of a 21-year-old medical student with severe-to-profound sensorineural hearing loss. The greatest difficulties reported by the patient were for stethoscope use and slide presentations in darkened rooms. Successful audiologic management was accomplished for this patient via use of a behind-the-ear (BTE) FM system for classroom use and a "homemade" amplified stethoscope that enabled him to hear diagnostic heart sounds for clinical use. The amplified stethoscope provided greater low-frequency gain for this patient than was available through other commercial units.

Improving the frequency specificity of the auditory brain stem response

Several investigators have suggested that the use of tonal stimuli shaped with nonlinear windowing functions can improve the frequency specificity of the auditory brain stem response (ABR). This study investigated the effects of different windowing functions on the ABR for 30 normal-hearing adults and 30 adults with high-frequency hearing loss. These hearing-impaired patients often produce an abnormal click-evoked ABR because of the influence of the high-frequency loss. Each subject was evaluated using a click stimulus and a 500 Hz tone burst gated with one linear and four nonlinear windowing functions. There were no significant differences in wave V latency between the groups for any of the five windowed tone burst conditions. These results suggest that any of the windowing functions used would be effective for 500 Hz tonal ABRs with this population of hearing-impaired adults.

Comparison of three hearing aid fittings using the Speech Intelligibility Rating (SIR) Test

This study compared the effects of three different hearing aids on subjective ratings of speech intelligibility. Insertion gain measurements on KEMAR indicated that the hearing aid fittings differed primarily in midfrequency gain. The test passages of the Speech Intelligibility Rating Test (SIR) were recorded onto tape through each hearing aid. The processed passages were presented monaurally to 13 subjects with hearing loss limited to frequencies above 2000 Hz. They rated five passages through each frequency responses (FR) in a randomized order. Each subject was retested within 2 or 3 days to assess test-retest reliability. Results indicated that the FR with the most midfrequency amplification did not differ significantly from the aid with the least amount of midfrequency gain. However, the FR with intermediate midfrequency gain received significantly lower ratings than did FR with most gain. Examination of the data from individual subjects indicated that the SIR results did not show differences among the FRs for the majority of subjects.

Effects of an adaptive filter hearing aid on speech recognition in noise by hearing-impaired subjects

In a digitally controlled adaptive filter, ongoing detection and spectral analysis of quasi steady state noise are performed, and analog filter parameters are adjusted to provide greatest attenuation in frequency regions where noise energy is greatest. Attenuation introduced by the filter affects both speech and noise signals in the attenuation region. Effects of a master hearing aid incorporating an adaptive filter chip were assessed by measuring aided speech recognition threshold in noise with and without the filter. Performance of four hearing-impaired subjects showed that filter effects were related both to the frequency spectrum of the noise and to the distribution of speech information by frequency. No improvement in speech recognition threshold was seen for broadband speech materials in broadband noise. Better performance was observed for low-frequency noise in combination with speech materials for which the important information was confined to high frequencies.

Individual data from the 3M/Vienna extracochlear implant

Five patients who received the 3M/Vienna extracochlear implant were given a standard battery of tests before and after implantation. Pure-tone audiograms, hearing aid evaluation, and promontory threshold and dynamic range stimulation were conducted to evaluate implant candidacy and to determine whether a particular patient met the criteria for inclusion in the study. Speech reading tests were also given before implantation. Postimplantation testing consisted of thresholds and tolerance levels for pure tones and speech reading with and without acoustic stimulation. Tests on environmental sounds, speech discrimination, and word discrimination were scored. Minimal Auditory Capabilities (MAC) Battery scores were determined on MAC, I, II, IV, V, VII, VIII, and XII subtests over several time intervals (sessions). The hearing results varied greatly among patients. All five patients expressed satisfaction and are presently wearing their units.