![]() ![]() ![]() The SeboTek HD2 hearing aid, in all of its fitting options, does not produce an occlusion effect. The importance of eliminating the occlusion effect has been reported in this paper. The SeboTek HD2 hearing aid has been designed to allow the dispenser to customize the output level consistent with the listener’s dynamic range requirements. However, hearing aids are designed to limit the output to the listener’s uncomfortable level, which at times is sufficiently low, limiting the dynamic range. A high OSPL90 (output sound pressure level with 90 dB input) is required for a hearing aid to have a wide dynamic range. The SeboTek HD2 hearing aid transducers provide very low internal noise and exceptional sound quality. ![]() ![]() The conclusion regarding internal noise is that, for preferred sound quality, internal noise should be low. The SeboTek HD2 features adjustable Voice Priority and Ambient Noise Reduction to facilitate improved hearing in noise. SeboTek has addressed this issue by applying advanced smoothing algorithms and acoustic coupling that eliminates long sound tube effects by placing the receiver in the ear canal close to the eardrum rather at the ear level. Peaks and valleys in the frequency response result in poor sound quality and lead to acoustic feedback and/or a limiting of the upper amplification limits of the hearing aid. The following features are designed into the SeboTek HD2 hearing aid to provide acoustic transparency: However, it is based on and measures only narrow bands of frequencies in such systems, and as such, does not have application to wideband hearing aids, such as the SeboTek HD2 series. A test for telephony systems, the PESQ (Perceptual Evaluation of Speech Quality) is a family of standards comprising a test methodology for automated assessment of the speech quality as experienced by a user. The test attempted to scale and relate eight dimensions of sound quality (softness, brightness, clarity, fullness, nearness, loudness, spaciousness, and overall impression) to the listening experience. Noise and Hearing AidsĪ Judgement of Sound Quality (JSQ) test has been developed and used to assess the performance of hearing aids (Gabrielsson, Schenkman, & Hagerman, 1988 Gabrielsson, Hagerman, Bech-Kristensen, & Lundberg, 1990 Lundberg, Ovegård, Hagerman, Gabrielsson, & Brändström, 1992 Narendran & Humes, 2003), but the analysis seems to indicate that its application to sound quality is not as applicable as originally thought. Based on studies previously reported in this paper, it may be that attention is being focused partly in the wrong direction – not just to improving the signal-to-noise ratio (SNR) through noise reduction and speech enhancement algorithms, but adding to this, a wider frequency bandwidth as provided by the SeboTek HD2 series. Missing in these studies has been the potential impact of a wider bandwidth because of the limited range of the hearing aids used. Similarly, noise reduction algorithms implemented in wearable hearing aids revealed no significant intelligibility benefit, but improved ease of listening and listening comfort for hearing-impaired listeners (Bentler, Wu, Kettelet, & Hurtig, 2008). When evaluated, some speech algorithms may show a speech quality improvement, but not an improvement in speech intelligibility (Loizou, 2007 Hu & Loizou, 2007). Contemporary hearing aids have been designed with proprietary speech and noise algorithms, including the SeboTek HD2. ![]()
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