Digital signal processing in hearing instruments has brought new perspectives to the compensation of hearing impairment and may result in alleviation of the adverse effects of hearing problems. This ...study compares a commercially available digital signal processing hearing aid (HA) (Senso) with a modern analogue HA with programmable fitting (Logo). The HAs tested are identical in appearance and, in spite of a different mode of operation, the study design ensured blinding of the test subjects. Outcome parameters were: improvements in speech recognition score in noise (ΔSRSN) with the HAs; overall preference for HA; overall satisfaction; and various measures of HA performance evaluated by a self-assessment questionnaire. A total of 28 experienced HA users with sensorineural hearing impairment were included and 25 completed the trial. No significant differences were found in ΔSRSN between the two HAs. Eleven subjects indicated an overall preference for the digital HA, 10 preferred the analogue HA and 4 had no preference. Concerning overall satisfaction, 8 subjects rated the digital HA superior to the analogue one, whereas 7 indicated a superior rating for the analogue HA and 10 rated the HAs equal. Acceptability of noise from traffic was the only outcome parameter which gave a significant difference between the HAs in favour of the digital HA. It is concluded that there are no significant differences in outcome between the digital and analogue signal processing HAs tested by these experienced HA-users.
The annoyance of noise in hearing instruments caused by electromagnetic interference from Global Systems for Mobile Communication (GSM) and Digital European Cordless Telecommunication (DECT) mobile ...telephones has been subjectively evaluated by test subjects. The influence on speech recognition from the GSM and DECT noises was also determined. The measurements involved 17 hearing-impaired subjects. The annoyance was tested with GSM and DECT noise, each one mixed with continuous speech, a mall environment noise, or an office environment noise. Speech recognition was tested with the DANTALE word material mixed with GSM and DECT noise. The listening test showed that if noise level is acceptable so also is speech recognition. The results agree well with an investigation carried out on normal-hearing subjects. If a hearing instrument user is to be able to use a telephone without annoyance, the input-related noise level must not exceed 47 dB SPL for GSM and 46 dB SPL for DECT.
This paper reports on the clinical evaluation of a commercially available head-worn programmable 3-channel automatic gain control (AGC) hearing instrument (Siemens, Triton 3000). A preliminary ...fitting procedure is developed for the 3-channel AGC amplification system, which is compared by 26 experienced hearing instrument wearers with their own single-channel AGC instruments. The benefits of both amplification systems are assessed by speech audiometry at different signal-to-noise ratios utilizing German rhyme test speech material. In addition, subjective judgements concerning sound quality, speech intelligibility and comparison with the subject's own instrument are evaluated. The results indicate that the multichannel compression instrument is superior to single-channel aids in competitive speech situations. If the 3-channel AGC instrument is used as an automatic noise reduction system in patients requiring a certain amount of low-frequency gain, a markedly better speech recognition can be achieved compared to the subject's personal aids.
The concept of a MEMS-based acoustical sensor microarray cluster that can be used in a hearing instrument to improve speech intelligibility in a noisy reverberant environment has been presented. The ...proposed sensor microarray cluster has a cubic geometry where five identical MEMS-based microarrays of acoustical sensors constitute each side of a cubic and the bottom of the cube has been used for mounting and interconnection purposes. The steerable beams of each individual sensor microarray are used to be synchronized and polled using a microelectronic beam synthesis engine. In this way it will be possible to provide a three dimensional dynamic directionality for the sensor microarray cluster.The system can realize an improved dynamic directional speech acquisition system comparing to planar arrays for hearing instruments. The complete cubic sensor microarray cluster can be fabricated as a single die using Standard MEMS fabrication technology.
