Hearing Aid Applications Research Articles

Benefits of digital hearing aids

The author examines the physiological and psychological characteristics of the impaired ear and attempts to develop an understanding that can be used as the basis for designing a hearing aid. In addition, the limitations of today's hearing aids are examined. Secondly, new technology, such as digital signal processing, are examined as to its potential in hearing aid applications. Is digital processing practical and what are the potential benefits? Lastly, future directions of hearing aid research and development are discussed. >

Superdirective arrays for hearing aids.

Microphone arrays are the most effective of the techniques that have been proposed for improving speech intelligibility in noise for the hearing impaired. However, classical delay-and-sum beamforming provides very small amounts of array gain at low frequencies, while adaptive array processing has been shown to cancel the desired signal in the presence of strong room reflections. Superdirective arrays offer a heretofore overlooked solution in which optimal performance can be obtained for a stationary random noise field, but where the desired signal will not be canceled. A short constrained superdirective array suitable for hearing-aid applications is proposed in this paper, and its theoretical performance is evaluated.

A novel microphone preamplifier for use in hearing aids

A novel design for a microphone preamplifier for application in hearing aids is presented. The amplifier operates at a supply voltage of 1-1.3 V, the current drain is 70 pA. The maximum sound level allowed is more than 105 dB SPL, with a typical noise level of 28 dB SPL. Instead of the usual voltage sensing, current sensing of the microphone is used. The amplifier consists of a fully balanced charge-to-current amplifier with no external components required. A semicustom version of the design has been integrated in a standard BIMOS process.

Hearing Aid Evaluation and Fitting

Although many patients with hearing loss benefit from medical or surgical intervention, the vast majority have noncorrectable hearing disorders for which rehabilitation through amplification is indicated. There are three goals for the application of hearing aids: (1) to amplify normal conversational speech to levels that are maximally understandable to the patient; (2) to help the patient hear other environmental sounds; and (3) to assist in the educational or habilitative process for those children who sustain hearing loss prior to language and speech development. In addition, there are certain issues that require medical consideration when a wearable device is placed in the ear. This article describes current hearing aid technology; reviews its benefits, limitations, and application for typical patients; discusses the medical aspects of hearing aid fitting; and describes new hearing aid technology on the horizon.

Microphone with frequency pre-emphasis

A stepped frequency microphone particularly adapted to a hearing aid application provides a stepped frequency and has a low-pass sonic attenuator for providing to the undriven side of the microphone diaphragm a sonic counterpressure which at low frequencies substantially cancels ambient sound pressure delivered to the drive side of the diaphragm, the attenuator reducing this counterpressure at elevated frequencies to provide accentuated high frequency response.

ラウドネス写像型ディジタル補聴器の臨床応用 第一報

ラウドネス写像型ディジタル補聴器の臨床応用 第一報

Transfer functions and correction factors used in hearing aid evaluation and research.

In hearing aid research and application it is often necessary to transform the sound pressure level or acoustic gain measured at one physical point (e.g., 2 cc coupler) to an equivalent value at another physical point (e.g., tympanic membrane). Results of currently available studies on various transformations are summarized in this report. When no data were available, the desired transfer function was calculated as a linear combination of known contributing transfer functions. Values are given for the center frequencies of 1/3 octaves and critical bands.

Small acoustic tubes: New approximations including isothermal and viscous effects

Algebraic expressions are given (in fortran format for convenient use) that accurately approximate the value of the per unit-length acoustic impedance of small tubes (radii less than (1)/(16) acoustic wavelength) including isothermal and viscous effects. Their accuracy of typically 3% or better was obtained as a result of adding a shunt conductance term to the traditional approximations and including frequency-dependent multiplicative factors. The multiplicative factors are simple expressions for the real or imaginary terms, providing a factor of 40 increase in calculational speed over the full Bessel-function solution. Experimental verification is presented for various combinations of small tubes and cavities relevant to hearing aid applications, and the differences between the present approximations and previous approximations are illustrated using a 1-mm-diam tube as an example. Normalized complex series impedance and shunt admittance, characteristic impedance, time delay, and attenuation constant plots are provided as a reference utilizing the more nearly exact Bessel solution.

Microphone with stepped response

A microphone, particularly for hearing aid application, said microphone providing a stepped response characteristic relative to frequency wherein low frequency sounds will couple to the associated hearing aid with a restricted amount of amplification, while providing an emphasis or higher amplification for the higher frequencies in the bandwidth of interest.

Progressive hearing loss in children: hearing aids and other factors.

A sample of 20 children monitored for progressive hearing loss combined with 25 progressive loss cases were obtained. The effects of hearing aid use on progressive loss were examined in the context of etiology and other factors, particularly the time relations between hearing aid application and the period of progression. Results indicate a limited role played by hearing aids in progressive hearing loss. Hearing aid use was not implicate in 30 (69%) of the progressive loss subjects, questionably implicated in nine (20%), and probably implicated in five (11%). In the identification and monitoring of progressive hearing loss, it is unwise to conclude that hearing aid use is the cause of the deterioration without considering all other plausible factors.

H�rger�teversorgung bei Atresiekindern

The application of hearing-aids in cases of atresia of the external ear is problematical. In the past usually the children were fitted by body-aids or by ear level bone-conduction hearing-aids. Now we prefer a fitting more aesthetical and effective.

Untersuchungen zur Verdeckung von Ohrger�uschen mit Tinnitus-Maskern

Several studies in the USA have shown that troublesome effects of tinnitus aurium can be reduced by use of tinnitus maskers. These instruments, which look like behind the ear hearing aids, produce broad-band noise for tinnitus masking. Contrary to tinnitus aurium the artificial noise is localized outside the head, which generally seems to be less troublesome. Basing on an inquiry of 108 patients with tinnitus we selected a group of 56 suitable subjects to provide with tinnitus maskers or hearing aids for a few weeks. So it is reported on our experience with the application of tinnitus maskers and hearing aids in cases of tinnitus as well as the properties of these instruments are discussed.

An unusual application of a cros hearing aid

This paper describes the use of the CROS hearing aid principle on cases of congenital atresia. This young girl has had several operations which attempted to create a canal and tympanum, but the canal persisted in closing. A bone vibrator eyeglass hearing aid was fitted but was largely unsuccessful. Having a 50 db air-conduction loss was handicapping to this youngster, but the usual head worn hearing aid could not be fitted because of the lack of any canal, causing feedback. She refused a body type aid. The solution is this case was a CROS behind-the-ear hearing aid. She enjoys about a 25 db useful gain from this fitting.

A Study on the Application of Hearing Aids

The study was carried out in patients with gradual slope sensorineural hearing losses and those with conduction losses.The application of hearing aids was evaluated by performing speech discrimination test using both distorted speech and non-distorted speech, assessment of confusion matrix and a test for the easiness of hearing speech under different noise levels.The results obtained from the present study demonstrated that in the test for application of hearing aids, there were a few patients who showed a slight improvement in discrimination when tested with distorted speech, while a remarkable improvement was seen in discrimination when tested with non-distorted speech, and that in the test for easiness of hearing speech, difference was observed between the scores in quiet and those in noise when using hearing aids either with open canal earmold or with occluding earmold.From the above, it may be concluded that in order to perform adequate application test for hearing aids a test with distorted speech must be carried out in addition to that with standard speech.Moreover, it seems necessary to develop hearing aids in which frequency response can be altered according to the environmental noise levels

A Study on the Application of Hearing Aids

A Study on the Application of Hearing Aids

Application of Hearing Aids to Children

The purpose of this paper is to determine the standard use of hearing aids in children with sensorineural hearing loss. Follow up studies on the audiograms were carried out in 62 children with perceptive hearing loss making use of hearing aids.The results were summarized as follows:1. About 10per cent of the subjects showed more than 10dB aggravation in hearing after entrance to the special class for hearing impaired children.2. There was tendency in those cases that he aggravation in hearing was improved in some cases.3. No definite evidence of acoustic trauma due to the use of hearing aid was found in the residual hearing.4. Adequate guidance and superintendance are essential for hearing impaired children to use hearing aid effectively.

Application of Hearing Aids to Young Children

Application of Hearing Aids to Young Children

Studies on Application of Hearing Aids in Young Children

For the purpose of determining standard use of hearing aids by young children, a series of investigations regarding the models, the range of frequency response characteristics and the volume control of hearing aids were conducted on 22 sensorineural hearing impaired children who were skilful user of hearing aids and whose age ranged from eight to fourteen years.The results obtained are briefly summarized in the following.1. If the average hearing levels in speech range are not worse than 80dB, hearing aids in Japanese make (R Co.) may be helpful, but U. S. make (Z Co.) are more helpful for those children.2. Type of broad frequency response characteristics (300-4000cps) is more suitable than narrow (500-4000cps) for those hearing impaired children.3. In respect of volume control, comfortable level setting for normal ear is suitable even to those with impaired hearing.4. To obtain good speech discrimination by hearing aid, input sound level must be set as high as 70-80dB (P0=0.000204 dyne/cm2).

HEARING AIDS

Recent improvements in electrical hearing aids, released with confusing frequency by competing manufacturers, have imposed on the otolaryngologist new responsibilities and problems. His aurally handicapped patients confidently look to him to prescribe hearing devices or to give specific help in the selection of those best adapted to their individual requirements. To render this service satisfactorily requires a certain amount of elementary knowledge of the construction, performance and limitations of these instruments. To make more clear some of the physical features involved in the application of hearing aids we present some of the acoustic phenomena concerned in the problem. In the normal process of communicating ideas by speech there are several indispensable elements, namely, the speaker, the listener and a path of sound transmission. To insure a high degree of understandability each element of the combination must function properly; that is, Enunciation must be clear and loud. The listener's hearing