Active electronic cochlear implants for middle and inner ear hearing loss--a new era in ear surgery. I: Basic principles and recommendations on nomenclature

Hearing aids have fundamental disadvantages: (1) stigmatization of the patient; (2) the sound is often found to be unsatisfactory due to the limited frequency range and undesired distortion; (3) in many patients, the ear canal fitting device generally necessary leads to an occlusion effect; (4) acoustic feedback when amplification is high. Conventional hearing aids transmit sound into the ear canal via a small microphone. Sound has the disadvantage of requiring high output sound pressure levels for its transmission. This along with the necessary miniaturization of the loudspeaker as well as the resonances and reflections in the closed ear canal contribute to the disadvantages mentioned. In contrast, implantable hearing aids do not make sound signals but micromechanical vibrations. An implantable hearing aid has an electromechanical transducer instead of the loudspeaker of a conventional hearing aid. The hearing signal does not leave the transducer as sound but as a mechanical vibration which is directly coupled to the auditory system bypassing the air. This implantable hearing aid is either coupled to the tympanic membrane, the ossicular chain, the perilymph of the inner ear, or the skull. An implantable hearing aid is expected to have: 1 Better sound fidelity than a hearing aid 2 No ear canal fitting device, free ear canal 3 No feedback 4 Invisibility Requirements on electronic hearing implants designed for patients with conductive hearing loss differ from those on implants for sensorineural hearing loss. Conductive hearing loss requires the implant to replace the impedance transformation, thus being an impedance transformation implant (ITI). In various respects, the demands on an ITI are lower than the demands on an electronic hearing aid for patients with sensorineural hearing loss. The latter are mostly patients with a failure of the cochlea amplifier (CA). A damage to the CA is clinically discernible by a positive recruitment and loss of otoacoustic emissions (OAE). Since these patients form the majority of cases with sensorineural hearing loss, an active hearing implant for such patients should partially replace the function of the CA. Therefore, the suggestion is to refer to a CAI (cochlea amplifier implant). The implant expressions ITI (for patients with conductive hearing loss) and CAI (for patients with sensorineural hearing loss) used in this context allow nomenclatural association with the CI (cochlear implant) for complete inner ear failure as well as with the BSI (brainstem implant) in the case of hearing nerve failure.     

Impact of an audiology clinic in one general practice

There is a large demand for the provision of hearing aids. However, there are lengthy delays involved between referral and fitment of National Health Service (NHS) hearing aids. This report shows that a general practice based audiology clinic can lead to an increase in the number of patients referred and fitted with a hearing aid. The introduction of the clinic also led to reduced waiting times for patients to be fitted with hearing aids.     

Brainstem auditory evoked response (BER) in paedaudiological diagnosis (author's transl)

Intention of paedaudiology is to detect and to evaluate hearing loss in children. In new born and small infants, in children with behavioral disorders and multiple disabilities, the clinical techniques of audiometry are often not useful. The brainstem audiometry is a reliable alternative and not so cost intensive and time consuming as it is often assumed. Encouraging is this technique in regard of hearing aids: prevention of attaching unnecessary hearing aids, ruling out not appropriate fitted hearing aids and proper habilitation of unilateral hearing loss.     

Stapedectomy in profound cochlear loss

Stapedectomy can be used in certain patients with profound sensorineural hearing loss and stapes fixation to improve hearing to a level at which a hearing aid may be effective. This study reviews the outcomes of 11 patients with profound cochlear loss secondary to otosclerosis who underwent stapes surgery performed by the senior author (M.E.G.) over a 25-year period. Postoperative hearing aid usage was effective in 9 of 11 patients. Preoperatively, these patients derived no benefits from hearing aids. Stapedectomy may be of immense value in patients with the proper history and profound cochlear loss.     

The rehabilitation of conductive hearing impairment

Conductive hearing loss (CHL) usually is amenable to surgical correction. At times, patients with CHL may not be candidates for surgical correction, or they may refuse to undergo the procedure. In such a situation, the patient should be encouraged to try hearing aids, either conventional or bone conduction, depending on the pathologic condition. After a discussion of bone-conduction implantable hearing aids, the article discusses congenital aural atresia, otosclerosis, and the management of CHL after infratemporal fossa approach and transtemporal approaches.     

Hearing aid rehabilitation of hearing disorders in adults

Hearing-aid provision is still partly a medical task, in spite of technological progress and a confusing variety of types and models of devices. The diagnosis of the underlying disease, the appreciation of the consequences of hearing loss and the counseling of the hearing impaired person are prerequisites of the treatment. The physician should try to determine the etiology of the hearing loss. Also, a state-of-the-art otologic examination should be performed and the physician should be sensitive to the psychological and social consequences of the patient's hearing loss. For the assessment of fitted hearing aids, basic knowledge of the technical background is required. To measure hearing-aid benefit in the ENT office, suprathreshold and speech audiometry are indispensable tools.     

Reliability of monosyllabic discrimination tests in white noise for differentiating among hearing aids

In spite of criticism, monosyllabic discrimination tests are widely employed for hearing aid selection. The current study was designed to investigate the following questions: (1) How reliable is aided speech discrimination of monosyllables in a background of white noise? (2) Can differences among hearing aids be reliably demonstrated by measuring intelligibility of monosyllables in a background of white noise? and (3) Do hearing aids interact with hearing loss? Twenty subjects with mild-moderate sensorineural hearing losses participated in two experimental sessions. Four hearing aids were evaluated using the NU-6 monosyllables in a background of white noise (s/n = +20 dB). Since the standard deviation of the test-retest differences was 6%, differences between aids were not considered significant unless they exceeded 12%. An interaction between subjects and hearing aids was found; that is, the best aid for one person was not the best for all. Measuring monosyllabic word intelligibility in a background of white noise does not reliably identify a single best aid. However, one or more inferior aids were consistently eliminated in 80% of the subjects.     

Perceived sound quality of three bone-anchored hearing aid models

Eighteen patients judged the sound quality of the new Classic 300 and the existing HC 100 or HC 200 on 4 five-stage sound quality scales. Two of the scales relate to the perceptual dimensions softness and clarity, one relates to interference or noise and one relates to the overall impression. The evaluations were made, based on a questionnaire, in the patients' own homes and comprised the listening situations: TV news, music, conversation with two to three people in a noisy environment and one optional choice. The patients also stated which hearing aid was best in each situation and made a confidence rating for their selection. The patients were accustomed to wearing the HC 100 or HC 200. In these comparisons of the different bone-anchored hearing aid models, the Classic 300 received the best ratings overall. Seventeen patients changed their previously fitted hearing aid to a Classic 300 and satisfactory sound quality was undoubtedly one of the principal reasons. When it came to the confidence rating for their selections, some two-thirds of the patients stated that it was without hesitation or with little hesitation. Our overall conclusion is that the sound quality of bone-anchored hearing aids is satisfactory when it comes to clarity and overall impression. However, it may be expected that these patients with conductive losses get a better sound quality than other patients with sensorineural losses if the same type of aid is used.     

Comparison of two digital hearing aids

OBJECTIVE: The objective of this investigation was to compare real and perceived benefit for two currently marketed digital hearing aids, the Oticon DigiFocus and the Widex Senso. The hearing aids have different philosophies of design and fitting strategies; as a result, it was hypothesized that there would be performance differences. DESIGN: Twenty subjects with documented sensorineural hearing losses were fit with each of the two digital hearing aids. After 4 wk of use with each hearing aid, a battery of objective and subjective tests was completed to assess hearing aid benefit. RESULTS: No significant differences were found between the hearing aids as revealed by the objective testing of speech recognition and self-report inventories of hearing aid benefit. The DigiFocus was shown by real ear measurements to provide more high-frequency gain than the Senso. The Widex Senso was preferred by 13 of the 20 subjects (seven of 10 of the new hearing aid users). This may be explained, in part, by the increased high-frequency gain provided by the Oticon DigiFocus, which was perceived as having greater "harshness." CONCLUSIONS: Based on the results of this investigation, neither hearing aid processor was shown to be superior to the other. In addition, the least amount of objective benefit was shown in the presence of background noise.     

Comparison of measurements of the characteristics of directional microphone hearing aids in an IAC test room and an anechoic chamber

The purpose of this study was to assess the possibility of measuring directional microphone hearing aids (DMHAs) using standard hearing aid test instruments in a sound field environment. The use of DMHAs is increasing and research has shown that under certain difficult listening situations, superior results are obtained by hearing impaired individuals with directional versus omnidirectional microphone arrangements. However, valid electroacoustic evaluation of the DMHAs cannot be accomplished using the conventional hearing aid test box. The ideal environment for such evaluations is an anechoic chamber, a facility not found in most audiological clinics. Results show that if the proper precautions are observed, the electroacoustic characteristics of DMHAs can be measured in a sound field environment using conventional hearing aid test instrumentation. Validation of this procedure was carried out by comparing sound field results with those obtained in an anechoic chamber.     

Small abnormality of the middle ear--a genetically-induced defect?

Conductive and sensorineural hearing losses are of genetic origin in 20% to 60% of cases. In general, genetic abnormalities are more often expressed as a sensorineural hearing loss than as a conductive hearing loss. At present several genes for sensorineural hearing loss have been isolated. The most common genetically transmitted forms for isolated conductive hearing losses are otosclerosis and small malformations of the ossicles. To date no genes responsible for these deformations have been isolated. We present a family with four siblings having conductive hearing losses caused by ossification of the stapedial tendon. This finding is suggestive of an autosomal recessive inheritance. The early diagnosis of an hereditary conductive hearing loss contains the possibility for permitting normal development of speech.     

Effect of a hearing aid on progressive hearing loss

A group of 72 children with hearing aids followed in 4 different clinical settings presented progressive increase in sensorineural hearing loss. The mean hearing loss over time, the duration of hearing aid use and the gain were studied to test the hypothesis that continued progression in hearing loss was due to overly powerful amplification. No correlation was found between the progressive increased gain levels were associated with less progression in hearing loss than at lower gain levels. Therefore, the use of hearing aids was not directly and significantly related to the increase in hearing loss in the population studied. However according to the above criteria a few cases (4%) of progressive hearing loss did seem to be associated with hearing aid use.     

Presbyacusis, hearing aids and aging

This paper considers the factors of presbyacusis and age-related psychological changes in older adults in terms of their effects on the use or potential use of hearing aids as a means of improving aural communication. Data are presented on the prevalence of hearing impairment and the extent of hearing aid use in aging listeners. Four major classes of presbyacusis are described (sensory, neural, metabolic, and cochlear conduvtive) and a hearing aid prognosis is made for each type of disorder. It is shown that aging produces deficits in pure-tone thresholds, the speech reception threshold, and speech discrimination, but not all losses can be 'corrected' with a hearing aid. Binaural (stereophonic) devices are psychoacoustically superior to monaural devices; however, behavioral and personality changes in older patients often create problems of adaptation to the binaural aid. These changes may also affect the fitting of an aid and the patient's ability to learn to use it. Some practical suggestions are offered on the evaluation of hearing aids and it is emphasized that adequate orientation and counseling are typically required if hearing aid treatment is to be successful in presbyacusis.     

Critical notes on the fitting of hearing-aids in children (author's transl)

The fitting of hearing-aids in hearing-impaired children in the Federal Republic of Germany is insufficient. Misfittings are harmful to the children and cause unnecessarily high costs. Unfortunately there are no clinical experiences with competent controls to be found. Consequently, medical responsibility should be encouraged and a panel of experts created for the evaluation of all patients who require hearing aids. This system can then be used annually to maintain an effective quality cost control.     

Immobilization effects on contractile properties of aging rat skeletal muscle

Recent advances in miniaturization have provided clinicians with hearing aids that can be comfortably inserted as far as the bony portion of the ear canal. It is possible to take advantage of these deeply inserted hearing aids in new ways. For example, the physical vibrations of microphone and receiver components may be used to improve hearing aid gain through bone conduction. Three cases are presented that will introduce this phenomenon for two transcranial CROS fittings and for one unilateral otosclerosis fitting. In each case, functional gain measurements under headphones were obtained with the hearing aid receivers acoustically plugged. Considerable gain was still present. Potential benefits, ramifications, and side effects are discussed.     

流态化焙烧技术与国内发展情况

对广泛应用于氧化铝工业生产的三种流态化焙烧炉进行了分析和比较，指出了三种炉型各自的特点和不足。流态闪速焙烧炉和循环流态焙烧炉技术经验成熟，生产稳定性较强，气体悬浮焙烧炉能耗指标先进。并提出了引进应以流态化闪速焙烧炉优先，消化创新应以气体悬浮焙烧炉为基础。最后指出我国铝工业应以气体悬浮焙烧炉为基础，在消化吸收流态化焙烧技术的前提下发展创新，形成适合我国氧化铝工业特点的流态化焙烧炉。     

Improvements in speech perception by children with profound prelingual hearing loss: effects of device, communication mode, and chronological age

The present investigation expanded on an earlier study by Miyamoto, Osberger, Todd, Robbins, Karasek, et al. (1994) who compared the speech perception skills of two groups of children with profound prelingual hearing loss. The first group had received the Nucleus multichannel cochlear implant and was tested longitudinally. The second group, who were not implanted and used conventional hearing aids, was tested at a single point in time. In the present study, speech perception scores were examined over time for both groups of children as a function of communication mode of the child. Separate linear regressions of speech perception scores as a function of age were computed to estimate the rate of improvement in speech perception abilities that might be expected due to maturation for the hearing aid users (n=58) within each communication mode. The resulting regression lines were used to compare the estimated rate of speech perception growth for each hearing aid group to the observed gains in speech perception made by the children with multichannel cochlear implants. A large number of children using cochlear implants (n=74) were tested over a long period of implant use (m=3.5 years) that ranged from zero to 8.5 years. In general, speech perception scores for the children using cochlear implants were higher than those predicted for a group of children with 101-110 dB HL of hearing loss using hearing aids, and they approached the scores predicted for a group of children with 90-100 dB HL of hearing loss using hearing aids.     

A comparison of various methods of soft tissue management following the immediate placement of implants into extraction sockets

This study included 10 subjects with sensorineural hearing loss. They had not previously used hearing aids. The hearing aid fitting with "behind-the-ear' aids was based on the NAL method. Judging the sounds in their ordinary home environment, three sound situations (programmes) were selected, permitting the subjects to listen to one programme with speech, another with music and a third with "background noise'. For the group as a whole, significant differences were found between the sound quality judgements with and without the hearing aid. When the judgements of the programmes with background noise were excluded in the analysis, there were significant differences over time in the group as a whole on the scales for clarity and total impression.