Frequency Shaping in Hearing Aids

Physiological Measurement, 2004

Spectral enhancement is now being used in many hearing aids in an attempt to compensate for broadened cochlear filtering. However, spectral enhancement may be counteracted by multiband-compression algorithms designed to compensate for the reduced dynamic range of the impaired cochlea. An alternative scheme for spectral enhancement, contrast-enhancing frequency shaping (CEFS), has been proposed, which results in an improved neural representation of the first and second formants of voiced speech segments in the impaired ear. In this paper, models of the normal and impaired ear are used to assess the compatibility of CEFS with multiband compression. Model auditory nerve responses were assessed under four conditions: (1) unmodified speech presented to a normal ear; (2) amplified, unshaped speech presented to an impaired ear; (3) CEFS speech presented to an impaired ear; and (4) CEFS+multiband-compression speech presented to an impaired ear. The results show that multiband compression does not reduce the benefits of CEFS, and in some cases multiband compression assists in preventing distortion of the neural representation of formants. These results indicate that the combination of contrast-enhancing frequency shaping and multiband compression should lead to improved perception of voiced speech segments in hearing aid users.

Journal of the Acoustical Society of America, 1975

1997

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.Includes bibliographical references (leaf 47).by Kinuko Masaki.M.Eng

Ear and Hearing, 2019

Objectives: Hearing aids provide various signal processing techniques with a range of parameters to improve the listening experience for a hearing-impaired individual. In previous work, we reported significant differences in signal modification for mild versus strong signal processing in commercially available hearing aids. In this study, we extend this work to clinically prescribed hearing aid fittings based on best-practice guidelines. The goals of this project are to determine the range of cumulative signal modification in clinically-fit hearing aids across manufacturers and technology-levels, and the effects of listening conditions including signal-tonoise ratio (SNR) and presentation level on these signal modifications. Design: We identified a subset of hearing aids that were representative of a typical clinical setting. De-identified hearing aid fitting data were obtained from three audiology clinics for adult hearing-aid users with sensorineural hearing loss for a range of hearing sensitivities. Matching laboratory hearing aids were programmed with the de-identified fitting data.

1997

One of the major problems faced by hearing aid users when they desire more gain than the hearing aid can deliver is high-intensity oscillation called "whistling." This problem is due to acoustic feedback of the input signal to the microphone. In this thesis, the ability of frequency modulation to reduce this acoustic feedback was investigated. A real-time implementation of the algorithm was done on a DSP chip and both electroacoustic and psychoacoustic tests were made. It was found that this algorithm delivered a maximum additional stable gain of 7 dB.

Journal of the American Academy of Audiology, 2013

Background: Frequency-lowering signal processing in hearing aids has re-emerged as an option to improve audibility of the high frequencies by expanding the input bandwidth. Few studies have investigated the usefulness of the scheme as an option for bimodal users (i.e., combined use of a cochlear implant and a contralateral hearing aid). In this study, that question was posed.

2011

Frequency-lowering signal processing in hearing aids has re-emerged as an option to improve audibility of the high frequencies by expanding the input bandwidth. However, few studies have investigated the usefulness of the scheme as a bimodal option for cochlear implant users. In this study, that question was posed. It was hypothesized that, following fitting and a period of adjustment to a frequency-compression hearing aid, sound localization and speech perception would be improved compared to conventional amplification. More specifically, more high-frequency cues would be perceived in the hearing aid ear using frequency compression, thereby providing better sensitivity to interaural level differences when a cochlear implant is used contralaterally. There were two experiments in this study. In the first experiment, the goal was to determine if frequency compression was a better bimodal option than conventional amplification. Performance was assessed on tests of sound localization, s...

2006 IEEE International Conference on Acoustics Speed and Signal Processing Proceedings, 2006

This paper investigates the use of voicing information as an additional cue in contrast enhanced frequency shaping (CEFS) of speech to improve perception in the hearing impaired. The presented work builds on an existing system combining multiband compression with contrast enhanced frequency shaping (MICEFS) to restore the auditory nerve response of a hearing impaired listener. CEFS can improve the perception of voiced segments. Hence voicing cues are used to differentiate segments for processing. Alternative processing for unvoiced segments is investigated and shown to improve neural representation of unvoiced segments compared to using MICEFS processing alone.

Proceedings of the European Signal Processing …, 2008

Common types of hearing impairment are caused mainly by a loss of nearly instantaneous compressive amplification in the inner ear. Therefore, it seems plausible that the loss might be compensated by fast frequency-dependent compression in the hearing aid.

China-Japan Joint …, 2002

The auditory filter of hearing impaired is wider than that of normal hearing people. Thus, the frequency selectivity decreases because of increased of masking effects. We have focused on this wider auditory filter shape and developed a method in which the critical band is compressed along the frequency axis. We also implemented a system based on the proposed algorithms using "SIMULINK." To test our method, we conducted two experiments. The first evaluated the Mean Opinion Score (MOS) and the second was an articulation test. The quality and intelligibility of speech sounds were improved in Exp.1. In Exp.2, the articulation score was also improved when frequencies were compressed. These results show the feasibility of frequency compression algorithm for the hearing impaired people.