The first category of methods uses a (real-valued) spectro-temporal gain where the same gain is applied to two microphone signals (one on each hearing aid). Presently, methods that perform array processing while aiming to preserve interaural cues can be divided into two general categories. This increases the array gain, but results in the signals presented to the ears being generated from the same set of input signals making it necessary to take measures to control the interaural cues. Both hearing aids may work independently, but it is advantageous to link them together, treating all microphone channels as a unified array. In the case of bilateral hearing loss, a hearing aid is required at both ears. Methods such as fixed and adaptive beamforming and multichannel Wiener filtering are generally capable of better noise suppression and lower speech distortion than single-channel methods. Miniaturization has allowed modern hearing aids to utilize multiple microphones in compact devices, allowing the use of multimicrophone signal enhancement algorithms. This information should be preserved not only to maintain the benefit of SRM but also to allow the person to be aware of the spatial composition of his surroundings. However, any modification of the signals presented to the ears has the potential to distort the cues the ear uses to perceive the direction of sounds (e.g., interaural level difference (ILD) and interaural time difference (ITD)). Hence, in hearing aid algorithms, it is important to increase the signal-to-noise ratio (SNR) of the desired sound source in order to improve speech intelligibility. This can be explained by the fact that hearing-impaired persons have a higher speech reception threshold (SRT) for speech in noise and do not benefit as much from SRM as normal-hearing persons. SRM is the increased ability to hear signals in noise if the signal and noise have different perceived directions.Ĭompared to normal-hearing persons, hearing-impaired persons find it more difficult to handle cocktail party situations. ![]() One of these factors is the spatial separation of sound sources which leads to a spatial release from masking (SRM). The cocktail party effect is a major area of hearing research, and many important factors that are part of human ASA have been identified. One example of ASA is the so-called cocktail party effect, which describes the human ability to follow a conversation with a single target speaker while other interfering speakers are active. This process is referred to as auditory scene analysis (ASA). In these situations, the human auditory system is able to focus intentionally on a single sound source while suppressing other interfering sound sources. The purpose of this present discussion is to call attention to what appears to be many neglected aspects and pitfalls in applying binaural amplification to the hearing-impaired and to scrutinize, in light of previous experimentation, the current clinical methods frequently used in the evaluation and selection of hearing aids in general and binaural hearing aids in particular.Situations where we are exposed to a number of sound sources reaching our ears simultaneously are part of our everyday life. Each of these approaches reflects an attempt to provide both the normal and the hearing-impaired listener with a more complete auditory experience than previously was possible with a single reproduction or amplification system. ![]() A second interest, implemented by electronic miniaturization, is the binaural hearing aid. ![]() On one hand, there has been the influx of stereophonic sound in the attempt to reproduce the "sound space" attendant to original listening conditions. I Within the past few years, there has been a renewed and vigorous attempt to reproduce by unique electromechanical methods our multidimensional acoustic environment.
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