scholarly journals Effect of Type of Noise and Loudspeaker Array on the Performance of Omnidirectional and Directional Microphones

2006 ◽  
Vol 17 (06) ◽  
pp. 398-412 ◽  
Author(s):  
Michael Valente ◽  
Karen M. Mispagel ◽  
Juergen Tchorz ◽  
David Fabry
Keyword(s):  
Steady State ◽  
Hearing Aids ◽  
Background Noise ◽  
Directional Microphones ◽  
The Past ◽  
Directional Microphone ◽  
And Performance ◽  
Array Performance ◽  
Better Than

Differences in performance between omnidirectional and directional microphones were evaluated between two loudspeaker conditions (single loudspeaker at 180°; diffuse using eight loudspeakers set 45° apart) and two types of noise (steady-state HINT noise; R-Space™ restaurant noise). Twenty-five participants were fit bilaterally with Phonak Perseo hearing aids using the manufacturer's recommended procedure. After wearing the hearing aids for one week, the parameters were fine-tuned based on subjective comments. Four weeks later, differences in performance between omnidirectional and directional microphones were assessed using HINT sentences presented at 0° with the two types of background noise held constant at 65 dBA and under the two loudspeaker conditions.Results revealed significant differences in Reception Thresholds for Sentences (RTS in dB) where directional performance was significantly better than omnidirectional. Performance in the 180° condition was significantly better than the diffuse condition, and performance was significantly better using the HINT noise in comparison to the R-Space restaurant noise. In addition, results revealed that within each loudspeaker array, performance was significantly better for the directional microphone. Looking across loudspeaker arrays, however, significant differences were not present in omnidirectional performance, but directional performance was significantly better in the 180° condition when compared to the diffuse condition. These findings are discussed in terms of results reported in the past and counseling patients on the potential advantages of directional microphones as the listening situation and type of noise changes.

Improving Speech Intelligibility in Background Noise with an Adaptive Directional Microphone

2006 ◽  
Vol 17 (07) ◽  
pp. 519-530 ◽  
Author(s):  
Peter J. Blamey ◽  
Hayley J. Fiket ◽  
Brenton R. Steele
Keyword(s):  
Hearing Aids ◽  
Background Noise ◽  
Speech Intelligibility ◽  
Real Life ◽  
Normal Hearing ◽  
Directional Microphones ◽  
Directional Microphone ◽  
Hearing In Noise ◽  
Noise Test ◽  
Moderate Hearing Loss

Omnidirectional, supercardioid, and adaptive directional microphones (ADM) were evaluated in combination with the ADRO® amplification scheme for eight participants with moderate sloping hearing losses. The ADM produced better speech perception scores than the other two microphones in all noise conditions. Participants performed the Hearing in Noise Test sentences at -4.5 dB SNR or better, which is similar to the level achievable with normal hearing. The Speech, Spatial and Qualities of Hearing Scale indicated no disadvantages of using the ADM relative to the omnidirectional microphone in real-life situations. The ADM was preferred over the omnidirectional microphone in 54% of situations, compared to 17% preferences for the omnidirectional microphone, and 29% no preference. The combination of the ADM to improve SNR, and ADRO® to keep the signal output comfortable and audible provided near-normal hearing performance for people with moderate hearing loss. The ADM is the recommended microphone configuration for ADRO hearing aids.

scholarly journals Speech Perception in Noise: Directional Microphones versus Frequency Modulation (FM) Systems

2004 ◽  
Vol 15 (06) ◽  
pp. 426-439 ◽  
Author(s):  
M. Samantha Lewis ◽  
Carl C. Crandell ◽  
Michael Valente ◽  
Jane Enrietto Horn
Keyword(s):  
Speech Perception ◽  
Hearing Aids ◽  
Frequency Modulation ◽  
Speech Perception In Noise ◽  
Directional Microphones ◽  
Directional Microphone ◽  
Hearing In Noise ◽  
Noise Test ◽  
Diffuse Noise ◽  
Better Than

The major consequence of sensorineural hearing loss (SNHL) is communicative difficulty, especially with the addition of noise and/or reverberation. The purpose of this investigation was to compare two types of technologies that have been shown to improve the speech-perception performance of individuals with SNHL: directional microphones and frequency modulation (FM) systems. Forty-six adult subjects with slight to severe SNHL served as subjects. Speech perception was assessed using the Hearing in Noise Test (HINT) with correlated diffuse noise under five different listening conditions. Results revealed that speech perception was significantly better with the use of the FM system over that of any of the hearing aid conditions, even with the use of the directional microphone. Additionally, speech perception was significantly better with the use of two hearing aids used in conjunction with two FM receivers rather than with just one FM receiver. Directional microphone performance was significantly better than omnidirectional microphone performance. All aided listening conditions were significantly better than the unaided listening condition.

Performance of Directional Microphone Hearing Aids in Everyday Life

2002 ◽  
Vol 13 (06) ◽  
pp. 295-307 ◽  
Author(s):  
Mary T. Cord ◽  
Rauna K. Surr ◽  
Brian E. Walden ◽  
Laurel Olson
Keyword(s):  
Hearing Aids ◽  
Superior Performance ◽  
Directional Hearing ◽  
Directional Microphones ◽  
Use Patterns ◽  
Telephone Interviews ◽  
Directional Microphone ◽  
Perceived Performance ◽  
Level Of Satisfaction ◽  
Directional Hearing Aids

This study explored the use patterns and benefits of directional microphone technology in real world situations experienced by patients who had been fitted with switchable omnidirectional/directional hearing aids. Telephone interviews and paper-and-pencil questionnaires were used to assess perceived performance with each microphone type in a variety of listening situations. Patients who used their hearing aids regularly and switched between the two microphone configurations reported using the directional mode, on average, about one-quarter of the time. From brief descriptions, patients could identify listening situations in which each microphone mode should provide superior performance. Further, they reported encountering listening situations in which an omnidirectional microphone should provide better performance more frequently than listening situations in which the directional microphones should be superior. Despite using the omnidirectional mode more often and encountering situations in which an omnidirectional microphone should provide superior performance more frequently, participants reported the same level of satisfaction with each microphone type.

Effectiveness of Directional Microphones and Noise Reduction Schemes in Hearing Aids: A Systematic Review of the Evidence

2005 ◽  
Vol 16 (07) ◽  
pp. 473-484 ◽  
Author(s):  
Ruth A. Bentler
Keyword(s):  
Systematic Review ◽  
Noise Reduction ◽  
Hearing Aids ◽  
Small Sample Size ◽  
Careful Consideration ◽  
Small Sample ◽  
Experimental Conditions ◽  
Directional Microphones ◽  
Directional Microphone

A systematic review of the literature was undertaken to find evidence of real-world effectiveness of directional microphone and digital noise reduction features in current hearing aids. The evidence was drawn from randomized controlled trials, nonrandomized intervention studies, and descriptive studies. The quality of each study was evaluated for factors such as blinding, power of statistical analyses, and use of psychometrically strong outcome measures. Weaknesses in the identified studies included small sample size, resultant poor power to detect potentially worthwhile differences, and overlapping experimental conditions. Nine studies were identified for directional microphones, and the evidence (albeit weak) supports effectiveness. Two studies were identified for the noise reduction feature, and the evidence was equivocal. For the researcher, such a systematic review should encourage the careful consideration of appropriate methodologies for assessing feature effectiveness. For the clinician, the outcomes reported herein should encourage use of such a systematic review to drive clinical practice.

scholarly journals Sentence Recognition in Noise and Perceived Benefit of Noise Reduction on the Receiver and Transmitter Sides of a BICROS Hearing Aid

2013 ◽  
Vol 24 (10) ◽  
pp. 980-991 ◽  
Author(s):  
Kristi Oeding ◽  
Michael Valente
Keyword(s):  
Noise Reduction ◽  
Hearing Aids ◽  
Repeated Measures ◽  
Background Noise ◽  
Signal To Noise Ratio ◽  
Hearing Aid ◽  
Directional Microphones ◽  
Sentence Recognition ◽  
Clinically Significant ◽  
The Impact

Background: In the past, bilateral contralateral routing of signals (BICROS) amplification incorporated omnidirectional microphones on the transmitter and receiver sides and some models utilized noise reduction (NR) on the receiver side. Little research has examined the performance of BICROS amplification in background noise. However, previous studies examining contralateral routing of signals (CROS) amplification have reported that the presence of background noise on the transmitter side negatively affected speech recognition. Recently, NR was introduced as a feature on the receiver and transmitter sides of BICROS amplification, which has the potential to decrease the impact of noise on the wanted speech signal by decreasing unwanted noise directed to the transmitter side. Purpose: The primary goal of this study was to examine differences in the reception threshold for sentences (RTS in dB) using the Hearing in Noise Test (HINT) in a diffuse listening environment between unaided and three aided BICROS conditions (no NR, mild NR, and maximum NR) in the Tandem 16 BICROS. A secondary goal was to examine real-world subjective impressions of the Tandem 16 BICROS compared to unaided. Research Design: A randomized block repeated measures single blind design was used to assess differences between no NR, mild NR, and maximum NR listening conditions. Study Sample: Twenty-one adult participants with asymmetric sensorineural hearing loss (ASNHL) and experience with BICROS amplification were recruited from Washington University in St. Louis School of Medicine. Data Collection and Analysis: Participants were fit with the National Acoustic Laboratories’ Nonlinear version 1 prescriptive target (NAL-NL1) with the Tandem 16 BICROS at the initial visit and then verified using real-ear insertion gain (REIG) measures. Participants acclimatized to the Tandem 16 BICROS for 4 wk before returning for final testing. Participants were tested utilizing HINT sentences examining differences in RTS between unaided and three aided listening conditions. Subjective benefit was determined via the Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaire between the Tandem 16 BICROS and unaided. A repeated measures analysis of variance (ANOVA) was utilized to analyze the results of the HINT and APHAB. Results: Results revealed no significant differences in the RTS between unaided, no NR, mild NR, and maximum NR. Subjective impressions using the APHAB revealed statistically and clinically significant benefit with the Tandem 16 BICROS compared to unaided for the Ease of Communication (EC), Background Noise (BN), and Reverberation (RV) subscales. Conclusions: The RTS was not significantly different between unaided, no NR, mild NR, and maximum NR. None of the three aided listening conditions were significantly different from unaided performance as has been reported for previous studies examining CROS hearing aids. Further, based on comments from participants and previous research studies with conventional hearing aids, manufacturers of BICROS amplification should consider incorporating directional microphones and independent volume controls on the receiver and transmitter sides to potentially provide further improvement in signal-to-noise ratio (SNR) for patients with ASNHL.

The Effects of Noise Reduction Technologies on the Acceptance of Background Noise

2013 ◽  
Vol 24 (08) ◽  
pp. 649-659 ◽  
Author(s):  
Kristy Jones Lowery ◽  
Patrick N. Plyler
Keyword(s):  
Noise Reduction ◽  
Hearing Aids ◽  
Repeated Measures ◽  
Background Noise ◽  
Negative Effects ◽  
Directional Microphones ◽  
Repeated Measures Design ◽  
Noise Type ◽  
Data Collection And Analysis ◽  
Speech Spectrum

Background: Directional microphones (D-Mics) and digital noise reduction (DNR) algorithms are used in hearing aids to reduce the negative effects of background noise on performance. Directional microphones attenuate sounds arriving from anywhere other than the front of the listener while DNR attenuates sounds with physical characteristics of noise. Although both noise reduction technologies are currently available in hearing aids, it is unclear if the use of these technologies in isolation or together affects acceptance of noise and/or preference for the end user when used in various types of background noise. Purpose: The purpose of the research was to determine the effects of D-Mic, DNR, or the combination of D-Mic and DNR on acceptance of noise and preference when listening in various types of background noise. Research Design: An experimental study in which subjects were exposed to a repeated measures design was utilized. Study Sample: Thirty adult listeners with mild sloping to moderately severe sensorineural hearing loss participated (mean age 67 yr). Data Collection and Analysis: Acceptable noise levels (ANLs) were obtained using no noise reduction technologies, D-Mic only, DNR only, and the combination of the two technologies (Combo) for three different background noises (single-talker speech, speech-shaped noise, and multitalker babble) for each listener. In addition, preference rankings of the noise reduction technologies were obtained within each background noise (1 = best, 3 = worst). Results: ANL values were significantly better for each noise reduction technology than baseline; and benefit increased significantly from DNR to D-Mic to Combo. Listeners with higher (worse) baseline ANLs received more benefit from noise reduction technologies than listeners with lower (better) baseline ANLs. Neither ANL values nor ANL benefit values were significantly affected by background noise type; however, ANL benefit with D-Mic and Combo was similar when speech-like noise was present while ANL benefit was greatest for Combo when speech spectrum noise was present. Listeners preferred the hearing aid settings that resulted in the best ANL value. Conclusion: Noise reduction technologies improved ANL for each noise type, and the amount of improvement was related to the baseline ANL value. Improving an ANL with noise reduction technologies is noticeable to listeners, at least when examined in this laboratory setting, and listeners prefer noise reduction technologies that improved their ability to accept noise.

Performance of Directional Microphones for Hearing Aids: Real-World versus Simulation

2004 ◽  
Vol 15 (06) ◽  
pp. 440-455 ◽  
Author(s):  
Cynthia L. Compton-Conley ◽  
Arlene C. Neuman ◽  
Mead C. Killion ◽  
Harry Levitt
Keyword(s):  
Hearing Aids ◽  
Real World ◽  
Noise Source ◽  
Live Performance ◽  
Space Condition ◽  
Directional Microphones ◽  
Directional Microphone ◽  
Simulation Techniques ◽  
Hearing In Noise ◽  
The Absolute

The purpose of this study was to assess the accuracy of clinical and laboratory measures of directional microphone benefit. Three methods of simulating a noisy restaurant listening situation ([1] a multimicrophone/multiloudspeaker simulation, the R-SPACE™, [2] a single noise source behind the listener, and [3] a single noise source above the listener) were evaluated and compared to the "live" condition. Performance with three directional microphone systems differing in polar pattern (omnidirectional, supercardioid, and hypercardioid array) and directivity indices (0.34, 4.20, and 7.71) was assessed using a modified version of the Hearing in Noise Test (HINT). The evaluation revealed that the three microphones could be ordered with regard to the benefit obtained using any of the simulation techniques. However, the absolute performance obtained with each microphone type differed among simulations. Only the R-SPACE simulation yielded accurate estimates of the absolute performance of all three microphones in the live condition. Performance in the R-SPACE condition was not significantly different from performance in the "live restaurant" condition. Neither of the single noise source simulations provided accurate predictions of real-world (live) performance for all three microphones.

Predicting Hearing Aid Microphone Preference in Everyday Listening

2004 ◽  
Vol 15 (05) ◽  
pp. 365-396 ◽  
Author(s):  
Brian E. Walden ◽  
Rauna K. Surr ◽  
Mary T. Cord ◽  
Ole Dyrlund
Keyword(s):  
Hearing Aids ◽  
Background Noise ◽  
Environmental Variables ◽  
Daily Living ◽  
Hearing Impaired ◽  
Directional Hearing ◽  
Active Listening ◽  
Signal Source ◽  
Directional Microphone ◽  
Directional Hearing Aids

Seventeen hearing-impaired adults were fit with omnidirectional/directional hearing aids, which they wore during a four-week trial. For each listening situation encountered in daily living during a total of seven days, participants selected the preferred microphone mode and described the listening situation in terms of five environmental variables, using a paper and pencil form. Results indicated that hearing-impaired adults typically spend the majority of their active listening time in situations with background noise present and surrounding the listener, and the signal source located in front and relatively near. Microphone preferences were fairly evenly distributed across listening situations but differed depending on the characteristics of the listening environment. The omnidirectional mode tended to be preferred in relatively quiet listening situations or, in the presence of background noise, when the signal source was relatively far away. The directional mode tended to be preferred when background noise was present and the signal source was located in front of and relatively near the listener. Results suggest that knowing only signal location and distance and whether background noise is present or absent, omnidirectional/directional hearing aids can be set in the preferred mode in most everyday listening situations. These findings have relevance for counseling patients when to set manually switchable omnidirectional/directional hearing aids in each microphone mode, as well as for the development of automatic algorithms for selecting omnidirectional versus directional microphone processing.

Quantification of Directional Benefit across Different Polar Response Patterns

2004 ◽  
Vol 15 (09) ◽  
pp. 649-659 ◽  
Author(s):  
Ruth A. Bentler ◽  
Jessica L.M. Egge ◽  
Jill L. Tubbs ◽  
Andrew B. Dittberner ◽  
Gregory A. Flamme
Keyword(s):  
Speech Perception ◽  
Hearing Aids ◽  
Hearing Aid ◽  
Sound Quality ◽  
Response Patterns ◽  
Directional Microphones ◽  
Speech In Noise ◽  
Directional Microphone ◽  
Hearing In Noise ◽  
The Right

The purpose of this study was to assess the relationship between the directivity of a directional microphone hearing aid and listener performance. Hearing aids were fit bilaterally to 19 subjects with sensorineural hearing loss, and five microphone conditions were assessed: omnidirectional, cardioid, hypercardioid, supercardioid, and "monofit," wherein the left hearing aid was set to omnidirectional and the right hearing aid to hypercardioid. Speech perception performance was assessed using the Hearing in Noise Test (HINT) and the Connected Speech Test (CST). Subjects also assessed eight domains of sound quality for three stimuli (speech in quiet, speech in noise, and music). A diffuse soundfield system composed of eight loudspeakers forming the corners of a cube was used to output the background noise for the speech perception tasks and the three stimuli used for sound quality judgments. Results indicated that there were no significant differences in the HINT or CST performance, or sound quality judgments, across the four directional microphone conditions when tested in a diffuse field. Of particular interest was the monofit condition: Performance on speech perception tests was the same whether one or two directional microphones were used.

Effect of Signal-to-Noise Ratio on Directional Microphone Benefit and Preference

2005 ◽  
Vol 16 (09) ◽  
pp. 662-676 ◽  
Author(s):  
Brian E. Walden ◽  
Rauna K. Surr ◽  
Kenneth W. Grant ◽  
W. Van Summers ◽  
Mary T. Cord ◽  
...  
Keyword(s):  
Hearing Aids ◽  
Speech Intelligibility ◽  
Signal To Noise Ratio ◽  
Hearing Aid ◽  
Directional Hearing ◽  
Signal To Noise ◽  
Directional Microphones ◽  
Directional Microphone ◽  
The Individual ◽  
Directional Hearing Aids

This study examined speech intelligibility and preferences for omnidirectional and directional microphone hearing aid processing across a range of signal-to-noise ratios (SNRs). A primary motivation for the study was to determine whether SNR might be used to represent distance between talker and listener in automatic directionality algorithms based on scene analysis. Participants were current hearing aid users who either had experience with omnidirectional microphone hearing aids only or with manually switchable omnidirectional/directional hearing aids. Using IEEE/Harvard sentences from a front loudspeaker and speech-shaped noise from three loudspeakers located behind and to the sides of the listener, the directional advantage (DA) was obtained at 11 SNRs ranging from -15 dB to +15 dB in 3 dB steps. Preferences for the two microphone modes at each of the 11 SNRs were also obtained using concatenated IEEE sentences presented in the speech-shaped noise. Results revealed that a DA was observed across a broad range of SNRs, although directional processing provided the greatest benefit within a narrower range of SNRs. Mean data suggested that microphone preferences were determined largely by the DA, such that the greater the benefit to speech intelligibility provided by the directional microphones, the more likely the listeners were to prefer that processing mode. However, inspection of the individual data revealed that highly predictive relationships did not exist for most individual participants. Few preferences for omnidirectional processing were observed. Overall, the results did not support the use of SNR to estimate the effects of distance between talker and listener in automatic directionality algorithms.

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