Subscribe to RSS
An Evaluation of Hearing Aid Beamforming Microphone Arrays in a Noisy Laboratory Setting
26 May 2020 (online)
People with hearing loss experience difficulty understanding speech in noisy environments. Beamforming microphone arrays in hearing aids can improve the signal-to-noise ratio (SNR) and thus also speech recognition and subjective ratings. Unilateral beamformer arrays, also known as directional microphones, accomplish this improvement using two microphones in one hearing aid. Bilateral beamformer arrays, which combine information across four microphones in a bilateral fitting, further improve the SNR. Early bilateral beamformers were static with fixed attenuation patterns. Recently adaptive, bilateral beamformers have been introduced in commercial hearing aids.
The purpose of this article was to evaluate the potential benefits of adaptive unilateral and bilateral beamformers for improving sentence recognition and subjective ratings in a laboratory setting. A secondary purpose was to identify potential participant factors that explain some of the variability in beamformer benefit.
Participants were fitted with study hearing aids equipped with commercially available adaptive unilateral and bilateral beamformers. Participants completed sentence recognition testing in background noise using three hearing aid settings (omnidirectional, unilateral beamformer, bilateral beamformer) and two noise source configurations (surround, side). After each condition, participants made subjective ratings of their perceived work, desire to control the situation, willingness to give up, and tiredness.
Eighteen adults (50–80 yr, M = 66.2, σ = 8.6) with symmetrical mild sloping to severe hearing loss participated.
Data Collection and Analysis:
Sentence recognition scores and subjective ratings were analyzed separately using generalized linear models with two within-subject factors (hearing aid microphone and noise configuration). Two benefit scores were calculated: (1) unilateral beamformer benefit (relative to performance with omnidirectional) and (2) additional bilateral beamformer benefit (relative to performance with unilateral beamformer). Hierarchical multiple linear regression was used to determine if beamformer benefit was associated with participant factors (age, degree of hearing loss, unaided speech in noise ability, spatial release from masking, and performance in omnidirectional).
Sentence recognition and subjective ratings of work, control, and tiredness were better with both types of beamformers relative to the omnidirectional conditions. In addition, the bilateral beamformer offered small additional improvements relative to the unilateral beamformer in terms of sentence recognition and subjective ratings of tiredness. Speech recognition performance and subjective ratings were generally independent of noise configuration. Performance in the omnidirectional setting and pure-tone average were independently related to unilateral beamformer benefits. Those with the lowest performance or the largest degree of hearing loss benefited the most. No factors were significantly related to additional bilateral beamformer benefit.
Adaptive bilateral beamformers offer additional advantages over adaptive unilateral beamformers in hearing aids. The small additional advantages with the adaptive beamformer are comparable to those reported in the literature with static beamformers. Although the additional benefits are small, they positively affected subjective ratings of tiredness. These data suggest that adaptive bilateral beamformers have the potential to improve listening in difficult situations for hearing aid users. In addition, patients who struggle the most without beamforming microphones may also benefit the most from the technology.
Portions of this project were presented at AudiologyNow in Indianapolis, IN, April 5–8, 2017.
This project was funded by Sonova and by the Dan and Margaret Maddox Charitable Fund.
- Aspell E, Picou E, Ricketts T. 2014; Directional benefit is present with audiovisual stimuli: limiting ceiling effects. J Am Acad Audiol 25 (07) 666-675
- Bentler R, Palmer C, Mueller HG. 2006; Evaluation of a second-order directional microphone hearing aid: I. Speech perception outcomes. J Am Acad Audiol 17 (03) 179-189
- Bentler RA, Egge JL, Tubbs JL, Dittberner AB, Flamme GA. 2004; Quantification of directional benefit across different polar response patterns. J Am Acad Audiol 15 (09) 649-659 quiz 660.
- Best V, Marrone N, Mason CR, Kidd Jr G. 2012; The influence of non-spatial factors on measures of spatial release from masking. J Acoust Soc Am 131 (04) 3103-3110
- Best V, Mejia J, Freeston K, van Hoesel RJ, Dillon H. 2015; An evaluation of the performance of two binaural beamformers in complex and dynamic multitalker environments. Int J Audiol 54 (10) 727-735
- Blamey PJ, Fiket HJ, Steele BR. 2006; Improving speech intelligibility in background noise with an adaptive directional microphone. J Am Acad Audiol 17 (07) 519-530
- Compton-Conley CL, Neuman AC, Killion MC, Levitt H. 2004; Performance of directional microphones for hearing aids: real-world versus simulation. J Am Acad Audiol 15 (06) 440-455
- Cord MT, Surr RK, Walden BE, Dyrlund O. 2004; Relationship between laboratory measures of directional advantage and everyday success with directional microphone hearing aids. J Am Acad Audiol 15 (05) 353-364
- Cornelis B, Moonen M, Wouters J. 2012; Speech intelligibility improvements with hearing aids using bilateral and binaural adaptive multichannel Wiener filtering based noise reduction. J Acoust Soc Am 131 (06) 4743-4755
- Cox RM, Alexander GC, Gilmore C. 1987; Development of the connected speech test (CST). Ear Hear 8 (5 Suppl) 119S-126S
- Cox RM, Alexander GC, Gilmore C, Pusakulich KM. 1988; Use of the connected speech test (CST) with hearing-impaired listeners. Ear Hear 9 (04) 198-207
- Dhar S, Humes LE, Calandruccio L, Barlow NN, Hipskind N. 2004; Predictability of speech-in-noise performance from real ear measures of directional hearing aids. Ear Hear 25 (02) 147-158
- Edmonds BA, Culling JF. 2005; The spatial unmasking of speech: evidence for within-channel processing of interaural time delay. J Acoust Soc Am 117 (05) 3069-3078
- Edmonds BA, Culling JF. 2006; The spatial unmasking of speech: evidence for better-ear listening. J Acoust Soc Am 120 (03) 1539-1545
- Gnewikow D, Ricketts T, Bratt GW, Mutchler LC. 2009; Real-world benefit from directional microphone hearing aids. J Rehabil Res Dev 46 (05) 603-618
- Hornsby BW, Ricketts TA. 2007; Effects of noise source configuration on directional benefit using symmetric and asymmetric directional hearing aid fittings. Ear Hear 28 (02) 177-186
- Humes LE, Wilson DL. 2003; An examination of changes in hearing-aid performance and benefit in the elderly over a 3-year period of hearing-aid use. J Speech Lang Hear Res 46 (01) 137-145
- Jespersen CT, Olsen S. 2003; Does directional benefit vary systematically with omnidirectional performance?. Hear Rev 10: 16-25
- Keidser G, Dillon H, Carter L, O’Brien A. 2012; NAL-NL2 empirical adjustments. Trends Amplif 16 (04) 211-223
- Keidser G, Dillon H, Convery E, Mejia J. 2013; Factors influencing individual variation in perceptual directional microphone benefit. J Am Acad Audiol 24 (10) 955-968
- Killion MC, Christensen LA. 1998; The case of the missing dots: Al and SNR loss. Hear J 51 (05) 32-34
- Killion MC, Niquette PA, Gudmundsen GI, Revit LJ, Banerjee S. 2004; Development of a quick speech-in-noise test for measuring signal-to-noise ratio loss in normal-hearing and hearing-impaired listeners. J Acoust Soc Am 116 (4 Pt 1) 2395-2405
- Kochkin S. 2000; MarkeTrak V: “why my hearing aids are in the drawer”: the consumers’ perspective. Hear J 53 (02) 34, 36 39-41
- Kochkin S. 2010; MarkeTrak VIII: consumer satisfaction with hearing aids is slowly increasing. Hear J 63: 19-20
- Kompis M, Dillier N. 1994; Noise reduction for hearing aids: combining directional microphones with an adaptive beamformer. J Acoust Soc Am 96 (03) 1910-1913
- Kompis M, Dillier N. 2001; Performance of an adaptive beamforming noise reduction scheme for hearing aid applications. II. Experimental verification of the predictions. J Acoust Soc Am 109 (03) 1134-1143
- Kuk F, Keenan D, Lau C-C, Ludvigsen C. 2005; Performance of a fully adaptive directional microphone to signals presented from various azimuths. J Am Acad Audiol 16 (06) 333-347
- Lotter T, Vary P. 2006; Dual-channel speech enhancement by superdirective beamforming. EURASIP J Appl Signal Process 2006: 1-14
- McArdle RA, Wilson RH. 2006; Homogeneity of the 18 QuickSIN[TM] lists. J Am Acad Audio 17 (03) 157-167
- McCormack A, Fortnum H. 2013; Why do people fitted with hearing aids not wear them?. Int J Audiol 52 (05) 360-368
- Naylor G. 2016; Theoretical issues of validity in the measurement of aided speech reception threshold in noise for comparing nonlinear hearing aid systems. J Am Acad Audiol 27 (07) 504-514
- Nilsson M, Soli SD, Sullivan JA. 1994; Development of the hearing in noise test for the measurement of speech reception thresholds in quiet and in noise. J Acoust Soc Am 95 (02) 1085-1099
- Picou EM, Aspell E, Ricketts TA. 2014; Potential benefits and limitations of three types of directional processing in hearing aids. Ear Hear 35 (03) 339-352
- Picou EM, Moore TM, Ricketts TA. 2017; The effects of directional processing on objective and subjective listening effort. J Speech Lang Hear Res 60 (01) 199-211
- Picou EM, Ricketts TA. 2014; Increasing motivation changes subjective reports of listening effort and choice of coping strategy. Int J Audiol 53 (06) 418-426
- Picou EM, Ricketts TA. 2017; How directional microphones affect speech recognition, listening effort and localisation for listeners with moderate-to-severe hearing loss. Int J Audiol 56 (12) 909-918
- Picou EM, Ricketts TA, Hornsby BW. 2013; How hearing aids, background noise, and visual cues influence objective listening effort. Ear Hear 34 (05) e52-e64
- Plomp R. 1986; A signal-to-noise ratio model for the speech-reception threshold of the hearing impaired. J Speech Hear Res 29 (02) 146-154
- Preves DA, Sammeth CA, Wynne MK. 1999; Field trial evaluations of a switched directional/omnidirectional in-the-ear hearing instrument. J Am Acad Audiol 10 (05) 273-284
- Ricketts T, Dhar S. 1999; Comparison of performance across three directional hearing aids. J Am Acad Audiol 10 (04) 180-189
- Ricketts T, Henry P. 2002; Evaluation of an adaptive, directional-microphone hearing aid. Int J Audiol 41 (02) 100-112
- Ricketts T, Mueller HG. 2000; Predicting directional hearing aid benefit for individual listeners. J Am Acad Audiol 11 (10) 561-569 quiz 575.
- Ricketts TA, Henry PP, Hornsby BW. 2005; Application of frequency importance functions to directivity for prediction of benefit in uniform fields. Ear Hear 26 (05) 473-486
- Ricketts TA, Hornsby BW. 2003; Distance and reverberation effects on directional benefit. Ear Hear 24 (06) 472-484
- Ricketts TA, Hornsby BWY. 2006; Directional hearing aid benefit in listeners with severe hearing loss. Int J Audiol 45 (03) 190-197
- Sherbecoe RL, Studebaker GA. 2002; Audibility-index functions for the connected speech test. Ear Hear 23 (05) 385-398
- Sherbecoe RL, Studebaker GA. 2003; Audibility-index predictions of normal-hearing and hearing-impaired listeners’ performance on the connected speech test. Ear Hear 24 (01) 71-88
- Studebaker GA. 1985; A “rationalized” arcsine transform. J Speech Hear Res 28 (03) 455-462
- Taylor B. 2003; Speech-in-noise tests: how and why to include them in your basic test battery. Hear J 56 (01) 40-43
- Valente M, Fabry DA, Potts LG. 1995; Recognition of speech in noise with hearing aids using dual microphones. J Am Acad Audiol 6 (06) 440-449
- Walden BE, Surr RK, Cord MT. 2003; Real-world performance of directional microphone hearing aids. Hear J 56 (11) 40-42
- Walden BE, Surr RK, Grant KW, Van Summers W, Cord MT, Dyrlund O. 2005; Effect of signal-to-noise ratio on directional microphone benefit and preference. J Am Acad Audiol 16 (09) 662-676
- Welker DP, Greenberg JE, Desloge JG, Zurek PM. 1997; Microphone-array hearing aids with binaural output. II. A two-microphone adaptive system. IEEE Trans Speech Audio Process 5: 543-551
- Wu Y-H. 2010; Effect of age on directional microphone hearing aid benefit and preference. J Am Acad Audiol 21 (02) 78-89
- Wu YH, Bentler RA. 2010; Impact of visual cues on directional benefit and preference: part I—laboratory tests. Ear Hear 31 (01) 22-34
- Zurek PM. 1993. Binaural advantages and directional effects in speech intelligibility. In: Studebaker GA, Hochberg I. Acoustical Factors Affecting Hearing-Aid Performance. Boston, MA: Allyn & Bacon; 255-276