SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
State-of-the-art hearing aids incorporate advances in signal processing, miniaturization, and programmability. This technological progress has been accompanied by parallel enhancements in evaluating and fitting strategies. In addition, in the past several years, knowledge has increased about the influences of amplification on hearing ability and about the influences of hearing ability on benefit from amplification.
The present study provides new data on perceptual and physiological modifications associated with hearing aid (HA) fitting. Eight sensorineural hearing-impaired (SNHI) listeners participated. They had symmetrical hearing loss and were being fitted with binaural HAs for the first time. Perceptual performances were measured four times during auditory rehabilitation, using an intensity discrimination task and a loudness-scaling task. Pure tones of two different frequencies were used, one well amplified by HAs and the other weakly amplified. Two intensity levels were also tested, one rated 'soft' by SNHI listeners and the other 'loud'. Auditory brainstem responses (ABRs) to click stimulation were recorded. All measures were performed without HA. Results were consistent with the auditory acclimatization effect: most modifications induced by HA fitting were found at loud intensity levels and at high frequency, i.e., for acoustic information that was newly available to the listener. While both ears had similar hearing loss and aided gains, some differences between ears appeared in both perceptual tasks and in ABRs. In the right ear, a shortening of wave V latency paralleled perceptual modifications. The present results suggest that HA-fitting induces functional plasticity at the peripheral level of the auditory system.
This pilot study was designed to examine the effects of either providing or withholding subject-driven, postfitting electroacoustic changes (fine tuning) on hearing aid performance as measured by tests of speech recognition in noise, sound quality, and benefit. A group of adult first-time hearing aid users with moderate, high-frequency sensorineural hearing loss was studied over a 5-month postfitting period. Half of the group served as a control group; half constituted the treatment group. Treatment consisted of making as many postfitting electroacoustic manipulations as the participants' complaints/observations required. These adjustments were withheld from the control group individuals. Group performance differences were assessed using the COSI, two versions of the APHAB, a Satisfaction scale, a Sound Quality tool, and the SIN test. Analysis revealed no statistically significant differences in the control and treatment groups' performances or perceived benefit at any of the five postfitting test sessions. These data suggested that there was no measurable advantage to be derived from making postfitting frequency-gain adjustments of 10 dB or less to hearing aids with wide dynamic range compression fitted in the manner described in this article. Definitive studies of the effects of postfitting electroacoustic fine tuning must be undertaken.
Gains in stump volume have been documented in trans-tibial amputees while walking in custom made under-sized, total surface-bearing, vacuum-assisted sockets (Board et al., 2001). These gains raised doubts as to whether the sockets were truly under-sized and concerns that using an over-sized socket with vacuum-assist could lead to swelling, resulting, in discomfort or pain. The purposes of the present study were to determine if: (a) walking in a vacuum-assisted socket causes the stump to retain or gain volume in excess of the available socket volume and (b) the resulting increase in stump volume with an over-sized socket causes discomfort, pain, and/or the skin to redden. The results of this study showed the stump retained or gained volume in excess of the available socket volume while walking in vacuum-assisted sockets of various sizes. The stump lost less volume than predicted, or gained volume, in under-sized sockets. It also gained more volume than predicted in over-sized sockets. No discomfort, pain, or skin reddening, resulting from the volume gain was reported by any of the subjects after walking in an over-sized socket. This change in fluid balance towards a net gain supports the findings by Board et al. (2001) that vacuum-assist ensures a good fit during the day in ambulatory trans-tibial traumatic amputees with mature stumps.
OBJECTIVE: The purpose of this study was to characterize the sensorineural hearing losses of a group of children and adults along three parameters important to the hearing instrument fitting process: 1) audiometric configuration, 2) asymmetry of loss between ears, and 3) progression of loss over several years. DESIGN: Audiograms for 248 60- and 61-yr-old adults and 227 6-yr-old children were obtained from the audiological database at Boys Town National Research Hospital. Based on right-ear air-conduction thresholds, the configurations were assigned to one of six categories: sloping, rising, flat, u-shaped, tent-shaped, and other. Left- and right-ear thresholds were compared to determine asymmetry of loss. Progression of loss was evaluated for 132 children for whom additional audiograms over an 8-yr period were available. RESULTS: In general, the children's hearing losses were more evenly distributed across configuration categories while most of the adult's audiograms were sloping or u-shaped in configuration. The variability of loss at each frequency was greater for the children than the adults for all configuration categories. Asymmetrical losses were more common and the degree of asymmetry at each frequency was more extensive among the children than the adults. A small number of children showed either improved or deteriorated hearing levels over time. In those children for whom progressive hearing loss occurred, no frequency was more vulnerable than another. CONCLUSIONS: The results of the present study suggest that substantial differences in audiological characteristics exist between children and adults. Implications for amplification include the development of appropriate fitting protocols for unusual audiometric configurations as well as protocols for binaural amplification in cases of asymmetric hearing losses.
OBJECTIVE: The objective of the present study is to improve the efficiency of the fitting procedure of cochlear implant processors by making use of measurements of the electrically evoked compound actio potential (ECAP) and live-voice speech. DESIGN: In a randomised prospective cross-over design we compare speech performance of eighteen adult subjects when following the conventional fitting procedure to a procedure in which we use the profile of the ECAP threshold levels across the full electrode array measured intra-operatively. The overall level of the profile is shifted (by an equal amount of current units per electrode) until we find the threshold for live speech (new T levels) and the loudness comfort level (new C levels). Each fitting procedure is tested for 6 wk. Speech performance is measured in quiet and in noise every other week. RESULTS: The results show little difference between the scores (Dutch CVC words) for the conventional fitting procedure and the ECAP based fitting, although the T and C levels may differ markedly. CONCLUSION: The new fitting procedure is much faster and easier in the initial phase. Further improvement of performance may be obtained in a later stage of the fitting procedure by changing some individual electrodes on the basis of subjective responses.
To compensate for undercorrection, regression, or irregular astigmatism, contact lenses are sometimes fit after excimer laser photorefractive keratectomy (PRK). We fit 13 eyes (eight patients) with aspheric rigid gas permeable (RGP) contact lenses following PRK. Patients were fit for various reasons, and they were all previous RGP contact lens wearers. Eight of 13 eyes could not be corrected with spectacles to the same acuity as before PRK. With RGP contact lenses, all patients were corrected to the same acuities as before PRK. The mean base curve of the preoperative RGP lenses was 7.98 +/- 0.36 mm (SD); the mean power was -5.92 D +/- 2.88 D (SD). Postoperative lenses had a mean base curve of 8.03 mm +/- 0.41 mm (SD) and mean power of -5.5 D +/- 3.08 D (SD). Fitting RGP lenses after PRK was uncomplicated, and all lenses were as well tolerated after PRK as they had been before the procedure.
A qualified hearing aid fitting is only possible if the ENT doctor not only prescribes the device, but also conscientiously checks the comparative adjustments made by the hearing aid acoustician. In deciding, which of the tested hearing aids achieves the best and most appropriate improvement of hearing, the physician should first thoroughly study the acoustician's fitting protocol, which contains comparative results of all devices tested. The subjective satisfaction of the patient with his hearing aid can be determined in a detailed conversation or with a special questionnaire. The examination of the otoplastic is as necessary as the improvement of speech discrimination under free field conditions, especially with additional noise. With in situ measurement, the individual transmission characteristics of the hearing aid and the otoplastic are tested in a few minutes. Conscientious control of the fitted hearing aid is only possible with loudness scaling. The scaling function shows clearly whether the fitted aid has adequate amplification, is not too loudly adjusted, and whether the field of pleasant hearing has been considered.
Generally in keratoconus the corneal apex displacement is inferior in position and bilateral in expression. Two young male keratoconic subjects enrolled in the Dundee University Scottish Keratoconus Study (DUSKS) demonstrated with corneal topography the presence of unilateral superior keratoconus. Successful visual rehabilitation of a superior cone with contact lens fitting represents a particular challenge to the contact lens practitioner. This report discusses the management of two such cases.
Casting distortion and inadequate handling in the dental laboratory are 2 factors that can cause misfit between a cast framework and the implant analogs in the master cast. This article describes the CrescoTi Precision procedure, which has been developed for correction of misfit between cast titanium frameworks and supporting dental implants. The simplicity and accuracy of the procedure appear to demonstrate technical progress toward obtaining optimal precision of fit of the superstructure components, thereby eliminating stress forces that may be transformed to the peri-implant bone.
In order to find an adequate fitting strategy for digital compression hearing aids a combination of two interactive fitting strategies was developed, one of these based on frequency specifice loudness (ScalAdapt) and the other based on overall loudness and on sound quality (Cambridge Procedure). This new fitting strategy was tested against the sound and overall loudness based strategy and against a prescriptive fitting strategy in a 2-weeks field test with questionnaires and in laboratory measurements, subjectively as well as objectively. With six sensorineural hearing impaired participants no straightforward results were achieved. Additionally, the different testing procedures indicate (in tendency) different fitting strategies to be superior. More subjects will have to be tested and innovative evaluation methods have to be considered.
OBJECTIVE: At least two rationales are available for fitting wide dynamic range compression hearing aids. The goal of one rationale is to normalize loudness, and the goal of the second rationale is to maximize speech intelligibility. Neither rationale has been validated against other fitting rationales for the range of input levels common to the hearing aid user in the real world. The goal of the study was to compare the two rationales when implemented in a 2-channel compression hearing aid. DESIGN: Loudness normalization and speech intelligibility maximization were implemented using the Independent Hearing Aid Fitting Forum (IHAFF) and the National Acoustic Laboratories' Nonlinear (NAL-NL1) prescriptive formulas. Twenty-four subjects (eight for each of three groups of mild flat, moderate/severe flat, and steeply sloping hearing loss) participated in the study. Each subject completed an initial laboratory test, field test, and final laboratory test. The laboratory test consisted of a paired-comparison judgment for each prescriptive formula using four stimuli under both quiet and noisy listening conditions and a sentence recognition test using Bamford-Kowal-Bench sentences. In the field test, subjects evaluated the two rationales in individually selected everyday listening conditions for 4 wk. A digital simulation of the fitting rationales implemented in two channels was used for laboratory testing and a digital 2-memory, 2-channel device was used for field testing. Subjects adjusted the overall gain of each response to their preferred listening level in both the laboratory and in the field. RESULTS: Data collected in the laboratory before and after the field test showed no indication of significant learning or acclimatization effects. For each stimulus presented in the paired-comparison test more subjects preferred NAL-NL1 than preferred IHAFF. For the sentence recognition test, subjects performed significantly better with NAL-NL1 than IHAFF in a low-frequency weighted background noise. Sixteen out of 22 subjects who completed the field test reported a preference for the NAL-NL1 response. The remaining six subjects preferred IHAFF. The paired-comparison test and field test revealed that while the achieved root-mean-square (rms) difference between fittings for an input level of 65 dB SPL was small, the preference for either rationale was small. As the rms difference between fittings increased, the score in favor of NAL-NL1 increased. The correlation between the differences in satisfaction score obtained in the field test and the rms differences between the responses fitted was statistically significant. CONCLUSIONS: When the two fitting rationales prescribed substantially different responses for a 65 dB SPL input and these differences were achieved in the fitting, then the subjects preferred NAL-NL1. Even when the difference between fittings was small, the subjects preferred and performed better with NAL-NL1 when listening in a low-frequency weighted background noise.
OBJECTIVE: The objective of this study was to evaluate streamlined programming procedures for the Nucleus cochlear implant system with the Contour electrode array. DESIGN: Phase 1 involved an examination of the clinical MAPs for the first 103 recipients implanted with the Contour electrode array in the Melbourne Cochlear Implant Clinic, to examine the ability to predict the entire MAP based on a smaller number of clinically determined T- and/or C-levels. In phase 2, a subset of the streamlined procedures was selected and clinically evaluated, using speech perception and subjective preference measures. In the first study, the clinical MAP was compared with a MAP based on interpolating across three behavioral T-levels and three behavioral C-levels in a group of newly implanted subjects. The second study investigated the use of a single interpolated profile as the basis to creating the entire MAP. Initial evaluation compared the clinical MAP with two streamlined MAPs, one in which the C-level profile was derived from interpolation across a subset of T-levels and one in which the T-level profile was derived from interpolation across a subset of C-levels. In this case, the interpolated profile was based on five behavioral measures. Subsequently, the use of either three or a single T-level measure as the basis for the interpolated T-level profile was evaluated. Eighteen subjects, who were experienced with the clinical MAP before enrollment in the study, participated in the initial evaluation. The subjects were selected to include a group whose RMS deviation from clinical MAP levels, as determined in Phase 1, was greater than that of the wider population. RESULTS: The Phase 1 analysis showed that as expected, larger differences were observed between the clinical and derived MAP levels as interpolation was applied across fewer measured electrodes and that the use of a single interpolated profile to create the entire MAP resulted in the greatest deviation. No significant group mean difference was found in speech perception scores for newly implanted subjects when mapped with the clinical versus the streamlined MAP based on three behavioral T- and three behavioral C-level measures. For some individual subjects, scores were higher with the streamlined MAP. Subjective reports from the comparative performance questionnaire were consistent with these findings. No significant group mean difference in speech perception scores was found in comparing the clinical MAP with the streamlined MAPs based on a single interpolated T- or C-level profile created from five behavioral measures. Individual effects were observed; however, there was no consistent finding across subjects. The use of three rather than five behavioral T-level measures in the procedure did not result in significantly lower group mean scores; however, significantly poorer scores were obtained for three of the 10 individual subjects. The use of a MAP based on a single behavioral measure did result in poorer speech perception scores when compared with the MAP based on five behavioral T-level measures. These findings were consistent with subjective results from the performance questionnaires administered to determine preference for program across a range of listening situations. CONCLUSIONS: Two streamlined programming procedures are recommended for use in the clinical setting: (1) interpolating across three measured T-levels and three measured C-levels and (2) interpolating across five measured T- or C-levels and using the interpolated profile for fitting of the alternative profile.
PURPOSE: The purpose of this study was to examine the effects of the occlusal convergence angle of the abutment and the computer's luting space setting on the marginal and internal fit of Cerec 3 computer-aided design/manufacturing (CAD/CAM) all-ceramic crowns. MATERIALS AND METHODS: Mandibular second premolar all-ceramic crowns were fabricated for nine different conditions using Cerec 3: all combinations of abutments with three different total occlusal convergence angles (4, 8, and 12 degrees) with three different luting space settings (10, 30, and 50 microm). The completed crowns were seated on the abutments, and the marginal gaps were measured. The internal gaps between the crowns and abutments were also measured, using test-fit silicone paste. RESULTS: When the luting space was set to 10 microm, the marginal gaps of the crowns were greater than when it was set to 30 or 50 microm. When the luting space was set to 30 or 50 microm, the marginal gaps ranged from 53 to 67 microm and were not affected by the occlusal convergence angle of the abutment. The internal gaps were within a range of 116 to 162 microm and tended to decrease as the occlusal convergence angle of the abutment decreased. CONCLUSION: When the luting space was set to 30 microm, crowns with a good fit could be fabricated on the Cerec 3 system, regardless of the occlusal convergence angle of the abutment.
In an in-vitro study twenty artificial crowns were fabricated. A hardened stainless steel five piece die assembly was used to construct uniformed wax patterns and to record all measurements. The fit of ten PFM crowns before and after the application of porcelain using the porcelain but margin technique was compared to that of ten Dicor crowns. The results of this study indicated best fit with the metal crowns before the application of porcelain, while the PFM crowns were oversized and the Dicor crowns were undersized.
This study assessed changes in the characteristics of first-time hearing aid applicants in the past decade. Age, gender, date, type and ear of first hearing aid and audiometry were determined for a sample of 705 first-time hearing aid applicants. Thirteen cohorts resulted, according to the year of first visit to the dispenser. Differences in age, hearing loss, gender and type and ear of first hearing aid between cohorts were analysed. The mean age of first-time hearing aid users increased from 59.52 years in 1987 to 71.84 years in 1999. The mean pure-tone average hearing loss in the better ear (1, 2 and 4kHz) decreased from 69.06 dB in 1987 to 51.86dB in 1999. Relatively more males than females were fitted with hearing aids. Our conclusions are that people are being fitted with hearing aids at older ages and with smaller degrees of hearing loss.
Based on four series of patients (N=141) participating in clinical field testing of prosthetic feet and all provided with trans-tibial prostheses in accordance with the polypropylene component and assembly system developed by the International Committee of the Red Cross (ICRC) a series of quality benchmarks was developed and tested against historical data. The patient compliance demands were set for walking >1 km at 90 +/- 10%, non-users at 5 +/- 5%, discomfort at 10 +/- 10%, pain at 10 +/- 10%, and patient satisfaction at 90 +/- 10%. The technical performance demands were set for good socket fit at 60 +/- 10%, misalignment at 15 +/- 10%, insufficient craftsmanship at 10 +/- 10%, and requirements for socket change at 10 +/- 10%.
OBJECTIVE: In a series of experiments with a wearable binaural digital hearing aid, two hearing aid processing algorithms were compared. Both algorithms provided individual frequency shaping via a seven-band filterbank with compression limiting in the high-frequency channel. They differed in the processing of the low-frequency channel, using dynamic range compression for one (DynEar) and linear processing with compression limiting for the other (LinEar). In a pilot field test we found that LinEar/ DynEar preference based on use time could be predicted from auditory dynamic range data. For the subjects who preferred DynEar, the mean dynamic range was broader for low and mid frequencies and narrower for high frequencies, as compared with the LinEar preference subjects. These groupings were tested as predictors of user preference and performance in a main field test. DESIGN: The main study included 26 hearing aid users with symmetrical sensorineural losses. The algorithms were compared in a one-mo-long blind field test. A data logger function was included for objective recording of the total time each algorithm was used and how the volume controls were used. The preference was based on the time used for each algorithm and on subjective statements. Threshold signal-to-noise ratio (S/N-threshold) for speech was tested, and sound quality ratings were obtained through a questionnaire. We also tested the S/N-thresholds for the subjects' conventional (own) aids. RESULTS: The preference was correctly predicted by the dynamic range data on 12 out of 15 new cases. S/N-thresholds were lower for the preferred fittings compared with the nonpreferred fittings and with the subjects' own aids. In the questionnaire the preferred fittings were rated significantly higher in terms of overall impression and clearness. Because of the systematic way the DynEar-preference subjects adjusted the high-frequency DynEar gain, we speculate that upward spread of masking may have been a factor in preference and performance. Additionally, LinEar-preference subjects' preference and performance might have been influenced by excessive compression ratios with the DynEar processing in these cases. CONCLUSIONS: 1. Preference for DynEar versus LinEar depends on the auditory dynamic range. 2. S/N-thresholds for speech were better for the preferred fittings, which also were rated higher in terms of overall impression of sound quality and clearness.