A hearing aid or audio communication system includes an earpiece (10) that can be hidden in the ear canal, and which communicates wirelessly with a remote processor unit, or RPU (16), that enhances audio signals and can be concealed under clothing. Sounds from the environnment are picked up by a microphone (12) in the earpiece and sent with other information over a two-way wireless link (17) to the RPU (16). The wireless link (17) uses microwaves for component miniaturization. Furthermore, use of radar technology to implement the wireless link (17), with an RPU (16) interrogator and earpiece (10) transponder, reduces earpiece size and power, as no microwave oscillator is needed in the earpiece (10). Optional secondary wireless link circuitry (19) can be used between the RPU (16) and a cellular telephone system or other sources of information. Electronic voice recognition and response can control system operation.

Hearing aid with wireless remote processor

Purpose This work is aimed at addressing a seeming contradiction related to the use of noise-reduction (NR) algorithms in hearing aids. The problem is that although some listeners claim a subjectiv...

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Objective Measures of Listening Effort: Effects of Background Noise and Noise Reduction

This review traces the structural maturation of the human auditory system, and compares the timeline of anatomical development with cotemporaneous physiological and behavioral events. During the embryonic period, there is formation of basic structure at all levels of the system, i.e. the inner ear, the brainstem pathway, and the cortex. The second trimester is a time of rapid growth and development, and by the end of this period, the cochlea has acquired a very adult-like configuration. During the perinatal period, the brainstem reaches a mature state, and brainstem activity is reflected in behavioral responses to sound, including phonetic discrimination, and in evoked brainstem and early middle latency responses. The perinatal period is also the time of peak development of brainstem input to the cortex through the marginal layer, and of the long latency cortical potentials, the N(2) and mismatch negativity. In early childhood, from the sixth post-natal month to age five, there is progressive maturation of the thalamic projections to the cortex and of the longer latency Pa and P(1) evoked potentials. Later childhood, from six to twelve years, is the time of maturation of the superficial cortical layers and their intracortical connections, accompanied by appearance of the N(1) potential and improved linguistic discriminative abilities. Some consideration is given to the potential negative effects of deafness-induced sound deprivation during the perinatal period and childhood.

The human auditory system: A timeline of development

The cochlear implant is the most successful of all neural prostheses developed to date. It is the most effective prosthesis in terms of restoration of function, and the people who have received a cochlear implant outnumber the recipients of other types of neural prostheses by orders of magnitude. The primary purpose of this article is to provide an overview of contemporary cochlear implants from the perspective of two designers of implant systems. That perspective includes the anatomical situation presented by the deaf cochlea and how the different parts of an implant system (including the user's brain) must work together to produce the best results. In particular, we present the design considerations just mentioned and then describe in detail how the current levels of performance have been achieved. We also describe two recent advances in implant design and performance. In concluding sections, we first present strengths and limitations of present systems and then offer some possibilities for further improvements in this technology. In all, remarkable progress has been made in the development of cochlear implants but much room still remains for improvements, especially for patients presently at the low end of the performance spectrum.

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Cochlear implants: current designs and future possibilities.

This study compared the speech-in-noise perception abilities of children with and without diagnosed learning disabilities (LDs) and investigated whether naturally produced clear speech yields perce...

Speaking clearly for children with learning disabilities: sentence perception in noise.

Objectives:The purpose of this study is to determine how combinations of noise levels and reverberation typical of ranges found in current classrooms will affect speech recognition performance of typically developing children with normal speech, language, and hearing and to compare their performance

Combined effects of noise and reverberation on speech recognition performance of normal-hearing children and adults.

Recordings of nonsense syllables (VCV construction) were presented to groups of children aged 5, 7, 9, 11, and 13 years and young adults under monaural (reverberation time=0.6 s) and binaural (reverberation times=0, 0.4, and 0.6 s) conditions of reverberation. Phoneme identification performance was affected by age, reverberation, and mode of presentation (monaural versus binaural). The major findings were (1) phoneme identification scores in reverberant conditions improved with increasing age and decreased with increased reverberation time; (2) children’s performance in reverberant conditions did not reach asymptote until age 13; (3) binaural performance was consistently better than monaural performance for all age groups, with 5‐year‐olds showing the largest binaural advantage.

Children's perception of speech in reverberation.

The purpose of this study was to assess the accuracy of clinical and laboratory measures of directional microphone benefit. Three methods of simulating a noisy restaurant listening situation ([1] a multimicrophone/multiloudspeaker simulation, the R-SPACE, [2] a single noise source behind the listener, and [3] a single noise source above the listener) were evaluated and compared to the "live" condition. Performance with three directional microphone systems differing in polar pattern (omnidirectional, supercardioid, and hypercardioid array) and directivity indices (0.34, 4.20, and 7.71) was assessed using a modified version of the Hearing in Noise Test (HINT). The evaluation revealed that the three microphones could be ordered with regard to the benefit obtained using any of the simulation techniques. However, the absolute performance obtained with each microphone type differed among simulations. Only the R-SPACE simulation yielded accurate estimates of the absolute performance of all three microphones in the live condition. Performance in the R-SPACE condition was not significantly different from performance in the "live restaurant" condition. Neither of the single noise source simulations provided accurate predictions of real-world (live) performance for all three microphones.

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Performance of directional microphones for hearing aids: real-world versus simulation.

Two experiments were carried out to determine how manipulating the compression ratio and release time of a single-band wide dynamic range hearing aid affects sound quality. In experiment I, compression ratio was varied over the range from linear to 10:1 (low compression threshold, attack time=5 ms, release time=200 ms). In experiment II, compression ratios of 1.5, 2, and 3:1 were combined with release times of 60, 200, and 1000 ms (attack time=5 ms). Twenty listeners with sensorineural hearing loss rated the clarity, pleasantness, background noise, loudness, and the overall impression of speech-in-noise (Ventilation, Apartment, Cafeteria) processed through a compression hearing aid. Results revealed that increasing compression ratio caused decreases in ratings on all scales. Increasing release time caused ratings of pleasantness to increase, and ratings of background noise and loudness to decrease. At the 3:1 compression ratio, increasing the release time caused increases in ratings of clarity, pleasantne...

The effect of compression ratio and release time on the categorical rating of sound quality.

Objective The purpose of this study was to compare the accuracy of sound-direction identification in the horizontal plane by bilateral cochlear implant users when localization was measured with pink noise and with speech stimuli. Design Eight adults who were bilateral users of Nucleus 24 Contour devices participated in the study. All had received implants in both ears in a single surgery. Sound-direction identification was measured in a large classroom by using a nine-loudspeaker array. Localization was tested in three listening conditions (bilateral cochlear implants, left cochlear implant, and right cochlear implant), using two different stimuli (a speech stimulus and pink noise bursts) in a repeated-measures design. Results Sound-direction identification accuracy was significantly better when using two implants than when using a single implant. The mean root-mean-square error was 29 degrees for the bilateral condition, 54 degrees for the left cochlear implant, and 46.5 degrees for the right cochlear implant condition. Unilateral accuracy was similar for right cochlear implant and left cochlear implant performance. Sound-direction identification performance was similar for speech and pink noise stimuli. Conclusions The data obtained in this study add to the growing body of evidence that sound-direction identification with bilateral cochlear implants is better than with a single implant. The similarity in localization performance obtained with the speech and pink noise supports the use of either stimulus for measuring sound-direction identification.

Arlene C. Neuman

Papers

Combined effects of noise and reverberation on speech recognition performance of normal-hearing children and adults.

Children's perception of speech in reverberation.

Performance of directional microphones for hearing aids: real-world versus simulation.

The effect of compression ratio and release time on the categorical rating of sound quality.

Sound-direction identification with bilateral cochlear implants.