Why Do Hearing Aids Fail to Restore Normal Auditory Perception

One of the main issues in hearing-aid fittings is the abnormal perception of the user's own voice as too loud, "boomy," or "hollow." This phenomenon known as the occlusion effect be reduced by large vents in the earmolds or by open-fit hearing aids. This review provides an overview of publications related to open and closed hearing-aid fittings. First, the occlusion effect and its consequences for perception while using hearing aids are described. Then, the advantages and disadvantages of open compared with closed fittings and their impact on the fitting process are addressed. The advantages include less occlusion, improved own-voice perception and sound quality, and increased localization performance. The disadvantages associated with open-fit hearing aids include reduced benefits of directional microphones and noise reduction, as well as less compression and less available gain before feedback. The final part of this review addresses the need for new approaches to combine the advantages of open and closed hearing-aid fittings.

https://journals.sagepub.com/doi/pdf/10.1177/2331216516631741

Open Versus Closed Hearing-Aid Fittings: A Literature Review of Both Fitting Approaches

Background/objective This study evaluated the cognitive benefit of hearing aids (HA) in older patients with Alzheimer's disease (AD) and hearing loss (HL) after a 6- and 12-month period of utilization. Methods A multicenter double-blind randomized placebo-controlled trial was conducted in patients aged more than 65 years. A group was equipped with active HA for 6 months (active group) and a second group had placebo HA for 6 months (placebo group) followed by a secondary activation phase for a further 6 months (semi crossover procedure). Both groups were retested after a 12-month period. The primary endpoint was the change from baseline of the Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS Cog) after a 6-month period in both groups and after 6 months of secondary HA activation in the placebo group. A smaller cognitive decline should be obtained with HA use; an increase in ADAS Cog score of less than 6 points was defined a success. Results Fifty-one patients aged 68 to 99 years were included; 38 attended the 6-month visit: 18 in the active group and 20 in the placebo group. At 6 months, 14 (82.4%) successes were noticed in the active group, and 15 (88.2%) in the placebo group (p = 1.0); delta ADAS Cog in the active group was 1.8±5.3 and 1.3±5.3 in the placebo group (p = 0.8). In the placebo group, after the secondary HA activation, no significant improvement was observed. Conclusion No significant effect of HA use was observed after 6 months of follow-up in patients with AD and HL.

Efficacy of Hearing Aids on the Cognitive Status of Patients with Alzheimer's Disease and Hearing Loss: A Multicenter Controlled Randomized Trial.

This chapter reviews the general types of signal processing that are used in modern digital hearing aids. The focus is on concepts underlying the processing rather than on details of the implementation. The signal processing can be classified into three broad classes: (1) Processing to apply frequency- and level-dependent amplification to restore audibility and provide acceptable loudness, based on the hearing profile of the individual (usually the audiogram but sometimes taking into account the results of loudness scaling) and the preferences of the individual. Frequency lowering can be considered as an additional method for restoring the audibility of high-frequency sounds. (2) Sound cleaning, for example, partial removal of stationary noises or impulse sounds and reduction of acoustic feedback. Noise reduction may be achieved using both single-microphone and multiple-microphone algorithms, but only the latter have been shown to improve intelligibility. (3) Environment classification for automatically controlling the settings of a hearing aid in different listening situations. It is concluded that modern hearing aids can be effective in restoring audibility and providing acceptable loudness and listening comfort, but they are still of limited effectiveness in improving the intelligibility of speech in noisy situations.

Hearing Aid Signal Processing

An augmented reality (AR) platform combines several technologies in a system that can render individual "digital objects" that can be manipulated for a given purpose. In the audio domain, these may, for example, be generated by speaker separation, noise suppression, and signal enhancement. Access to the "digital objects" could be used to augment auditory objects that the user wants to hear better. Such AR platforms in conjunction with traditional hearing aids may contribute to closing the gap for people with hearing loss through multimodal sensor integration, leveraging extensive current artificial intelligence research, and machine-learning frameworks. This could take the form of an attention-driven signal enhancement and noise suppression platform, together with context awareness, which would improve the interpersonal communication experience in complex real-life situations. In that sense, an AR platform could serve as a frontend to current and future hearing solutions. The AR device would enhance the signals to be attended, but the hearing amplification would still be handled by hearing aids. In this article, suggestions are made about why AR platforms may offer ideal affordances to compensate for hearing loss, and how research-focused AR platforms could help toward better understanding of the role of hearing in everyday life.

Potential of Augmented Reality Platforms to Improve Individual Hearing Aids and to Support More Ecologically Valid Research.

To investigate speech recognition performance in noise with bilateral open-fi t hearing aids and as reference also with closed earmolds, in omnidirectional mode, directional mode, and directional mode in conjunction with noise reduction Design: A within-subject design with repeated measures across conditions was used Speech recognition thresholds in noise were obtained for the different conditions Study sample: Twenty adults without prior experience with hearing aids All had symmetric sensorineural mild hearing loss in the lower frequencies and moderate to severe hearing loss in the higher frequencies Results: Speech recognition performance in noise was not signifi cantly better with an omnidirectional microphone compared to unaided, whereas performance was signifi cantly better with a directional microphone (16 dB with open fi tting and 44 dB with closed earmold) compared to unaided With open fi tting, no signifi cant additional advantage was obtained by combining the directional microphone with a noise reduction algorithm, but with closed earmolds a signifi cant additional advantage of 08 dB was obtained Conclusions: The signifi cant, though limited, advantage of directional microphones and the absence of additional signifi cant improvement by a noise reduction algorithm should be considered when fi tting open-fi t hearing aids

/pdf/speech-recognition-in-noise-using-bilateral-open-fit-hearing-3w7l2bdq9w.pdf

Maria Persson

Papers

Speech recognition in noise using bilateral open-fit hearing aids: the limited benefit of directional microphones and noise reduction.

Mats Burström: Samtidsarkeologi. Introduktion till ett forskningsfält