Blog Archives

Effect of Maximum Power Output and Noise Reduction on Speech Recognition in Noise

Conclusions:

An MPO that was 10 dB lower than the default could negatively affect the signal-to-noise ratio (SNR) of the listening environment. However, NR could compensate for the degradation in SNR.

from the Journal of the American Academy of Audiology

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Evaluation of Different Signal Processing Options in Unilateral and Bilateral Cochlear Freedom Implant Recipients Using R-SpaceTM Background Noise

The results of this study suggest that the use of processing options that utilize noise reduction, like those available in ASC and BEAM, improve a CI recipient’s ability to understand speech in noise in listening situations similar to those experienced in the real world. The choice of the best processing option is dependent on the noise level, with BEAM best at moderate noise levels and ASC best at loud noise levels for unilateral CI recipients. Therefore, multiple noise programs or a combination of processing options may be necessary to provide CI users with the best performance in a variety of listening situations.

from the Journal of the American Academy of Audiology

Using power level difference for near field dual-microphone speech enhancement

In this contribution, a novel dual-channel speech enhancement technique is introduced. The proposed approach uses the dissimilarity between the power of received signals in the two channels as a criterion for speech enhancement and noise reduction. We claim that in near field conditions, where the distances between microphones and sound source are short, the difference in the received power levels at the two microphones is an estimate of the clean speech signal power. Then, apply this theory to present an optimum method for speech enhancement. Fortunately, the method has the ability to cope with problems such as transient noise and nearby microphones which are two of the main problems of the proposed dual-microphone speech enhancement techniques. Using objective speech quality measures and spectrogram analysis, we show that the proposed method results in improved speech quality.

from Applied Acoustics

Noise levels in neonatal intensive care unit and use of sound absorbing panel in the isolette

The noise level in our NICU is significantly above the universally recommended levels. Being inside the isolette protects infants from noise sources produced outside the isolette. However, very high noises are produced inside the isolette as well. Sound absorbing panel can be a simple solution and it attenuated the noise levels inside the isolette.

from the International Journal of Pediatric Otorhinolaryngology

Noise levels in neonatal intensive care unit and use of sound absorbing panel in the isolette

Conclusions
The noise level in our NICU is significantly above the universally recommended levels. Being inside the isolette protects infants from noise sources produced outside the isolette. However, very high noises are produced inside the isolette as well. Sound absorbing panel can be a simple solution and it attenuated the noise levels inside the isolette.

from the International Journal of Pediatric Otorhinolaryngology

Speech perception with hearing aids: Effects of noise reduction and directional microphone systems on amplified signals

Our objective was to measure the variations of speech reception threshold (SRT) in noise induced by hearing aids with or without noise reduction (NR) and directional microphone systems (DM). Data were collected from 10 normal hearing volunteers wearing bilateral hearing aids and tested in a sound field of speech and noise. SRT was measured in function of: 1) speech source azimuth (0°,90°,180°); 2) background noise (monophonic vs. quadraphonic); 3) amplification (unaided vs. linearly aided); 4) amplification mode (linear, NR, DM, NR+DM). Compared using a hearing aid linear setting, NR does not improve the SRT in monophonic noise, while it improves the SRT by 2-3dB in quadraphonic noise with frontal and lateral speech. DM in monophonic noise improves frontal SRT (1dB) and worsens lateral and posterior SRT, while in quadraphonic noise frontal SRT is further advantaged and the DM negative effect disappears. With both devices activated a stronger positive effect is evident for frontal SRT in both noise fields (2-4dB) and for lateral SRT in quadraphonic noise. These results confirm that NR and DM can facilitate SRT in adverse noise conditions for normal hearing persons, and the results are useful as a reference for hearing impaired persons.

from Audiological Medicine

Digital noise reduction: Outcomes from laboratory and field studies

from the International Journal of Audiology

The purpose of this study was to determine the impact of a digital noise reduction (DNR) scheme implemented in a current commercial hearing aid. In a double-blinded design, three conditions of onset time (4, 8, 16 seconds) were randomly assigned to the 25 subjects, plus one condition wherein the noise-reduction feature was disengaged. Subsequently, a fifth trial/condition, wherein the subject had access to three memories in which the different onsets were programmed, was carried out. For each of the five conditions, the subjects had an at-home trial, prior to obtaining self-report measures. Laboratory measures of speech perception showed no effect of the DNR, with or without the provision of visual cues. Laboratory-based ratings of ease of listening showed DNR-on (all onset times) to be rated significantly better than DNR-off; for ratings of listening comfort, the 4-second onset time was rated significantly lower (poorer) than the 8-second onset or the DNR-off condition; for ratings of sound quality, DNR-on or -off had no differential effect. Self-report measures indicated significantly higher aversiveness in the DNR-off condition compared to the pre-test scores