The Effects of Hearing Aid Digital Noise Reduction and Directionality on Acceptable Noise Level

Abstract

Objectives Two main digital signal processing technologies inside the modern hearing aid to provide the best conditions for hearing aid users are directionality (DIR) and digital noise reduction (DNR) algorithms. There are various possible settings for these algorithms. The present study evaluates the effects of various DIR and DNR conditions (both separately and in combination) on listening comfort among hearing aid users.Methods In 18 participants who received hearing aid fitting services from the Rehabilitation School of Shahid Beheshti University of Medical Sciences regularly, we applied acceptable noise level (ANL) as our subjective measure of listening comfort. We evaluated both of these under six different hearing aid conditions: omnidirectional-baseline, omnidirectional-broadband DNR, omnidirectional-multichannel DNR, directional, directional-broadband DNR, and directional-multichannel DNR.Results The ANL results ranged from −3 dB to 14 dB in all conditions. The results show, among all conditions, both the omnidirectional-baseline condition and the omnidirectional-broadband DNR condition are the worst conditions for listening in noise. The DIR always reduces the amount of noise that patients received during testing. The DNR algorithm does not improve listening in noise significantly when compared with the DIR algorithms. Although both DNR and DIR algorithms yielded a lower ANL, the DIR algorithm was more effective than the DNR.Conclusion The DIR and DNR technologies provide listening comfort in the presence of noise. Thus, user benefit depends on how the digital signal processing settings inside the hearing aid are adjusted.

Development of a Signal Processing Algorithm for Feedback (Noise) Reduction in Hearing Aids Using the Spectral Subtraction Technique

“…A study specified that individuals with hearing loss experience increased cognitive load and listening effort when the SNR is poor [13]. A study utilising the Acceptable Noise Level (ANL) as a subjective measure to assess the listening comfort of individuals who underwent hearing aid fitting services was conducted by a number of researchers [7], [14]. A fully integrated system-on-chip (SoC) hearing aid, which offered the potential for precise and adaptive gain control, enhancing the performance and user experience of hearing aids was also developed in the course of further research activities [15].…”

Auditory Recognition of Digit-in-Noise under Unaided and Aided Conditions in Moderate and Severe Sensorineural Hearing Loss

“…An omnidirectional microphone was set for all participants, and other digital signal processing algorithms (such as Sound Smoothing, eWind Screen, and Feedback Stopper) were inactivated. Based on the protocol introduced by Shahid Beheshti University of Medical Sciences (BUMS) for fitting the digital processing hearing aid, each participant was evaluated using the calibrated version of the Ling-6 sounds for evaluation of aided detection thresholds [16][17][18]. Despite the fact that DIN test was accomplished in suprathreshold level, the hearing aid was fitted so that the Ling-6 sounds were audible and discriminative in the level of 30 dB HL to provide equal audibility for all subjects.…”

Acceptable Noise Level in Children with Unilateral Cochlear Implant and Bimodal Hearing

“…In addition, it has been shown that ANL can be a good predictor of hearing aid satisfaction; people with lower ANL have better suppression in the auditory efferent system and usually are more satisfied with their hearing aids [8]. The lower ANL indicates better noise tolerance [8][9][10][11][12][13]. The Persian version of this test was validated by Ahmadi et al using a running female-talker story with a 12-talker babble in children [12].…”

“…The lower ANL indicates better noise tolerance [8][9][10][11][12][13]. The Persian version of this test was validated by Ahmadi et al using a running female-talker story with a 12-talker babble in children [12]. ANL test has been investigated just for the adults with CI [14] and it has not been yet applied for children with CI, especially for bimodal hearing.…”