Trends in Amplification最新文献

Studies have shown that unilateral cochlear implant users who have residual hearing in the contralateral ear can benefit from combining a hearing aid in the nonimplanted ear with their cochlear implant. The purpose of this study was to better understand the factors influencing decision making by adults. Adults who had discontinued hearing aid use shortly after cochlear implantation were selected from one Canadian cochlear implant program. An examination of hearing aid use revealed that of 96 patients, who used hearing aids preimplant, 49 had discontinued hearing aid use. Patient perspectives on the decision and experience of combining a hearing aid and a cochlear implant were collected through 12 individual semistructured interviews. The interviews were analyzed qualitatively to identify key themes. Questionnaires, based on the interview findings, were developed and sent to the 49 adults to further explore the factors affecting hearing aid decisions. Interview and questionnaire findings from 28 adults indicated that three factors primarily influenced patients' decision to discontinue hearing aid use: their perceptions of the experience with hearing aids prior to implantation, their views of superiority of a unilateral cochlear implant in comparison with hearing aids, and their perceptions of interference with sound quality when a cochlear implant and hearing aid were combined. This study provides information about patient perceptions, experiences, and understanding of the potential difficulties of a bimodal fitting that may assist clinicians in pre- and postimplant counseling.

Modern hearing instruments include many features addressing situation-specific and user-related amplification. The main tasks of the acoustician are the appropriate choice of hearing instruments and fitting them to hearing impaired individuals. This study aims at investigating the utility and importance of several hearing-aid features as assessed by hearing-aid acousticians. For this purpose, eight different hearing-aid features with three levels each are addressed in a discrete-choice experiment. Preferences for systematically varied combinations of the features are assessed with 143 acousticians, using an adaptive conjoint analysis conducted via the Internet. Based on the preference data, utility and importance of the features are calculated. Highest utility and importance are found for noise cancellation and directional microphones. Outcome of these two features do not differ significantly. In contrast, data management functions, that is, self-learning options, show lowest importance. Though the acousticians' professional experience reveal statistically significant influence on the assessment of some of the features' utility and importance, a clear impact of sociodemographic or subject-specific factors on the outcome cannot be found. The study can be seen as a first approach to determine the estimation of basic hearing-aid features assessed by acousticians. Results show the outstanding utility and importance of features addressing speech perception in adverse listening situations. Furthermore, the outcome reveals reservations of the acousticians regarding self-learning options of the instruments.

The capacity for internal rhythmic clocking involves a relationship between perceived auditory input and subsequent cognitive processing by which isochronous auditory stimuli induce a temporal beat expectancy in a listener. Although rhythm perception has previously been examined in cochlear implant (CI) users through various tasks based primarily on rhythm pattern identification, such tasks may not have been sufficiently nuanced to detect defects in internal rhythmic clocking, which requires temporal integration on a scale of milliseconds. The present study investigated the preservation of such rhythmic clocking in CI participants through a task requiring detection of isochronicity in the final beat of a four-beat series presented at different tempos. Our results show that CI users performed comparably to normal hearing (NH) participants in all isochronous rhythm detection tasks but that professionally trained musicians (MUS) significantly outperformed both NH and CI participants. These results suggest that CI users have intact rhythm perception even on a temporally demanding task that requires tight preservation of timing differences between a series of auditory events. Also, these results suggest that musical training might improve rhythmic clocking in CI users beyond normal hearing levels, which may be useful in light of the deficits in spectral processing commonly observed in CI users.

The middle ear muscle (MEM) reflex is one of two major descending systems to the auditory periphery. There are two middle ear muscles (MEMs): the stapedius and the tensor tympani. In man, the stapedius contracts in response to intense low frequency acoustic stimuli, exerting forces perpendicular to the stapes superstructure, increasing middle ear impedance and attenuating the intensity of sound energy reaching the inner ear (cochlea). The tensor tympani is believed to contract in response to self-generated noise (chewing, swallowing) and non-auditory stimuli. The MEM reflex pathways begin with sound presented to the ear. Transduction of sound occurs in the cochlea, resulting in an action potential that is transmitted along the auditory nerve to the cochlear nucleus in the brainstem (the first relay station for all ascending sound information originating in the ear). Unknown interneurons in the ventral cochlear nucleus project either directly or indirectly to MEM motoneurons located elsewhere in the brainstem. Motoneurons provide efferent innervation to the MEMs. Although the ascending and descending limbs of these reflex pathways have been well characterized, the identity of the reflex interneurons is not known, as are the source of modulatory inputs to these pathways. The aim of this article is to (a) provide an overview of MEM reflex anatomy and physiology, (b) present new data on MEM reflex anatomy and physiology from our laboratory and others, and (c) describe the clinical implications of our research.

Objectives: This descriptive summary of the literature provides an overview of the available studies (published between January 1980 and January 2009) on correlates of help-seeking behavior for hearing loss, hearing-aid uptake, hearing-aid use, and satisfaction with the device.

Methods: Publications were identified by structured searches in Pubmed and Cinahl and by inspecting the reference lists of relevant articles. The articles covered different stages that a person with hearing impairment may go through: prior to hearing aid fitting, the period covering the fitting and the period post hearing aid fitting. Inclusion of articles occurred according to strict inclusion and exclusion criteria. Data were extracted by two independent researchers. Thirty-nine papers were included that identified 31 factors examined in relation to the four outcome measures. These covered personal factors (e.g., source of motivation, expectation, attitude), demographic factors (e.g., age, gender) and external factors (e.g., cost, counseling). Only two studies covered the actual fitting process. There was only one factor positively affecting all four outcome variables. This was self-reported hearing disability. The vast majority of studies showed no relationship of age and gender with any of the outcome domains.

Discussion and conclusion: Whereas research of the last 28 years yielded valuable information regarding relevant and irrelevant factors in hearing aid health care, there are still many relevant issues that have never been investigated in controlled studies. These are discussed.

For the characterization of hearing aids, a new test method has been defined in the new International Electrotechnical Commission (IEC) standard 60118-15. For this characterization, the hearing aid will be set to actual user settings as programmed by standard fitting software from the hearing aid manufacturer. To limit the variation of programming outcomes, 10 standard audiograms, which cover the entire range of audiograms met in clinical practice, have been defined. This article describes how the set of standard audiograms has been developed. This set of standard audiogram has been derived by a vector quantization analysis method on a database of 28,244 audiograms. Using this analysis method, sets of typical audiograms have been obtained of sizes 12 and 60. It turned out that the smaller set could not be used for selecting audiograms as sloping audiograms were absent. Therefore, the larger set has been analyzed to provide seven standard audiograms for flat and moderately sloping hearing loss and three standard audiograms for steep hearing loss.

Hearing loss is a common health issue that affects nearly 10% of the world population as indicated by many international studies. The hearing impaired typically experience more frustration, anxiety, irritability, depression, and disorientation than those with normal hearing levels. The standard rehabilitation tool for hearing impairment is an electronic hearing aid whose main components are transducers (microphone and receiver) and a digital signal processor. These electronic components are manufactured by supply chain rather than by hearing aid manufacturers. Manufacturers can use custom-designed components or generic off-the-shelf components. These electronic components are available as application-specific or off-the-shelf products, with the former designed for a specific manufacturer and the latter for a generic approach. The choice of custom or generic components will affect the product specifications, pricing, manufacturing, life cycle, and marketing strategies of the product. The World Health Organization is interested in making available to developing countries hearing aids that are inexpensive to purchase and maintain. The hearing aid presented in this article was developed with these specifications in mind together with additional contemporary features such as four channels with wide dynamic range compression, an adjustable compression rate for each channel, four comfort programs, an adaptive feedback manager, and full volume control. This digital hearing aid is fitted using a personal computer with minimal hardware requirements in intuitive three-step fitting software. A trimmer-adjusted version can be developed where human and material resources are scarce.

Cochlear implants are highly successful neural prostheses for persons with severe or profound hearing loss who gain little benefit from hearing aid amplification. Although implants are capable of providing important spectral and temporal cues for speech perception, performance on speech tests is variable across listeners. Psychophysical measures obtained from individual implant subjects can also be highly variable across implant channels. This review discusses evidence that such variability reflects deviations in the electrode-neuron interface, which refers to an implant channel's ability to effectively stimulate the auditory nerve. It is proposed that focused electrical stimulation is ideally suited to assess channel-to-channel irregularities in the electrode-neuron interface. In implant listeners, it is demonstrated that channels with relatively high thresholds, as measured with the tripolar configuration, exhibit broader psychophysical tuning curves and smaller dynamic ranges than channels with relatively low thresholds. Broader tuning implies that frequency-specific information intended for one population of neurons in the cochlea may activate more distant neurons, and a compressed dynamic range could make it more difficult to resolve intensity-based information, particularly in the presence of competing noise. Degradation of both types of cues would negatively affect speech perception.

Numerous factors contribute to understanding speech in noisy listening environments. There is a clinical need for objective biological assessment of auditory factors that contribute to the ability to hear speech in noise, factors that are free from the demands of attention and memory. Subcortical processing of complex sounds such as speech (auditory brainstem responses to speech and other complex stimuli [cABRs]) reflects the integrity of auditory function. Because cABRs physically resemble the evoking acoustic stimulus, they can provide objective indices of the neural transcription of specific acoustic elements (e.g., temporal, spectral) important for hearing speech. As with brainstem responses to clicks and tones, cABRs are clinically viable in individual subjects. Subcortical transcription of complex sounds is also clinically viable because of its known experience-dependence and role in auditory learning. Together with other clinical measures, cABRs can inform the underlying biological nature of listening and language disorders, inform treatment strategies, and provide an objective index of therapeutic outcomes. In this article, the authors review recent studies demonstrating the role of subcortical speech encoding in successful speech-in-noise perception.

Nearly 300 million people worldwide have moderate to profound hearing loss. Hearing impairment, if not adequately managed, has strong socioeconomic and affective impact on individuals. Cochlear implants have become the most effective vehicle for helping profoundly deaf children and adults to understand spoken language, to be sensitive to environmental sounds, and, to some extent, to listen to music. The auditory information delivered by the cochlear implant remains non-optimal for speech perception because it delivers a spectrally degraded signal and lacks some of the fine temporal acoustic structure. In this article, we discuss research revealing the multimodal nature of speech perception in normally-hearing individuals, with important inter-subject variability in the weighting of auditory or visual information. We also discuss how audio-visual training, via Cued Speech, can improve speech perception in cochlear implantees, particularly in noisy contexts. Cued Speech is a system that makes use of visual information from speechreading combined with hand shapes positioned in different places around the face in order to deliver completely unambiguous information about the syllables and the phonemes of spoken language. We support our view that exposure to Cued Speech before or after the implantation could be important in the aural rehabilitation process of cochlear implantees. We describe five lines of research that are converging to support the view that Cued Speech can enhance speech perception in individuals with cochlear implants.