Using a signal cancellation technique to assess adaptive directivity of hearing aids

Wu, Yu-Hsiang; Bentler, Ruth A.

doi:10.1121/1.2735804

Cited by 8 publications

(5 citation statements)

References 15 publications

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“…For this reason, accurate quantification of SNR changes and speech cue distortions due to NR is vital to validate the NR outcomes (Gustafson et al 2014). Thus, we quantified SNR changes using the phase-inversion technique (Hagerman & Olofsson 2004) that has been implemented in HA evaluations [e.g., Hagerman and Olofsson (2004); Wu and Bentler (2007, 2009, 2011); Naylor and Johannesson (2009); Wu and Stangl (2013)]. This technique processes two noisy signals that are identical except having a different phase in noise and then adds the two outputs or deduct one from the other to extract signal and noise stimuli, respectively.…”

Section: Methodsmentioning

confidence: 99%

Effect of Noise Reduction on Cortical Speech-in-Noise Processing and Its Variance due to Individual Noise Tolerance

Kim

Bharadwaj

et al. 2021

Ear &Amp; Hearing

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Objectives: Despite the widespread use of noise reduction (NR) in modern digital hearing aids, our neurophysiological understanding of how NR affects speech-in-noise perception and why its effect is variable is limited. The current study aimed to (1) characterize the effect of NR on the neural processing of target speech and (2) seek neural determinants of individual differences in the NR effect on speech-in-noise performance, hypothesizing that an individual's own capability to inhibit background noise would inversely predict NR benefits in speech-in-noise perception.Design: Thirty-six adult listeners with normal hearing participated in the study. Behavioral and electroencephalographic responses were simultaneously obtained during a speech-in-noise task in which natural monosyllabic words were presented at three different signal-to-noise ratios, each with NR off and on. A within-subject analysis assessed the effect of NR on cortical evoked responses to target speech in the temporal-frontal speech and language brain regions, including supramarginal gyrus and inferior frontal gyrus in the left hemisphere. In addition, an acrosssubject analysis related an individual's tolerance to noise, measured as the amplitude ratio of auditory-cortical responses to target speech and background noise, to their speech-in-noise performance.Results: At the group level, in the poorest signal-to-noise ratio condition, NR significantly increased early supramarginal gyrus activity and decreased late inferior frontal gyrus activity, indicating a switch to more immediate lexical access and less effortful cognitive processing, although no improvement in behavioral performance was found. The across-subject analysis revealed that the cortical index of individual noise tolerance significantly correlated with NR-driven changes in speech-in-noise performance.Conclusions: NR can facilitate speech-in-noise processing despite no improvement in behavioral performance. Findings from the current study also indicate that people with lower noise tolerance are more likely to get more benefits from NR. Overall, results suggest that future research should take a mechanistic approach to NR outcomes and individual noise tolerance.

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Section: Methodsmentioning

confidence: 99%

Effect of Noise Reduction on Cortical Speech-in-Noise Processing and Its Variance due to Individual Noise Tolerance

Kim

Bharadwaj

et al. 2021

Ear &Amp; Hearing

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“…It has been shown, however, that if multiple noise sources are present, many adaptive algorithms default to a fixed directional pattern (e.g., cardioid, hypercardioid, supercardioid). 15 Since most listening environments have more than one source of noise/speech input, the result could be a fixed pattern such as the one used in this study. Based on these results, the outcome could be detrimental to word-recognition ability.…”

Section: Limitations Of This Study and Future Directionsmentioning

confidence: 99%

Effects of a directional mic on children's word recognition and novel-word learning

Stiles

Bentler

McGregor³

2008

The Hearing Journal

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Many hearing aid manufacturers have incorporated directional-microphone technology into their products to improve the signal-to-noise ratio (SNR) for the wearer. Although this technology has been shown to improve speech recognition in noise and user satisfaction for adults, there has been little research on its appropriateness in the pediatric population. Since children require greater audibility than adults to achieve equivalent performance on sentence recognition 1 and a greater SNR to recognize speech in multi-talker babble at a performance level equivalent to adults, 2,3 it seems logical that the technology would be useful for this population.Current data suggest that approximately 20% of audiologists typically fit directional hearing aids on children 0-6 months of age, 4 and 35% fit directional hearing aids to at least half of their pediatric clientele. 5 When speech is presented from the front and noise from the back, children have a 4.7-to 8-dB directional advantage in laboratory settings 6,7 and a 3-to 4-dB advantage in classroom environments 8 for microphone schemes providing the primary null in the back.Some have argued that directional microphones should be fitted with caution because, for safety reasons, children often need to be aware of sounds coming from all directions. 9 In addition, directional hearing aids may be disadvantageous to children as they may reduce the acoustic input necessary for learning localization and selective listening skills. This may ultimately reduce the number of incidental learning opportunities available to these children.The purpose of this study was to determine if off-axisplaced speech is negatively affected by fixed directionalmicrophone hearing aids in two situations that children face daily-recognizing old words and learning new words. We hypothesized that both recognizing familiar words and learning new words would be poorer in the directional condition (cardioid pattern) than in the omnidirectional condition for stimuli arriving from the rear sound field because sensitivity of the microphone may be reduced in the directional condition for signals arriving from the rear. STUDY OF WORD RECOGNITIONTwenty-four children (7 females; 17 males) between the ages of 6 and 10 years were enrolled in this component of the study, with the consent of their parents/guardians. They were screened for normal hearing and normal vision. MethodologyA GN Resound Metrix™ behind-the-ear hearing aid was programmed for a moderate, flat sensorineural hearing loss. Noise-reduction and feedback-management algorithms were disengaged. Using a custom-built standard earmold, the hearing aid was fitted to the right ear of a pediatric acoustic research manikin placed in the center of an anechoic space. A speaker was placed 1 meter from the manikin at the rear azimuth (180˚) for stimulus presentation. The output from the hearing aid was recorded to both left and right tracks using Adobe Audition 1.0 software, once with the hearing aid in omnidirectional mode and once with it in a fixed cardioid direc...

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“…This makes the technique problematic for real-ear measurement. Wu and Bentler (2007) used this signal cancellation technique to measure the directivity of an adaptive directional microphone hearing aid, mounted in free space. Their experiment used a 'jammer' noise signal to fix the polar response of the hearing aid, presented simultaneously with a probe signal.…”

Section: Sumariomentioning

confidence: 99%

Measuring real-ear signal-to-noise ratio: Application to directional hearing aids

Bell

Creeke

Lutman

2010

International Journal of Audiology

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Due to individual characteristics such as head size, earmould type, and earmould venting, the directional benefit that an individual will obtain from a hearing aid cannot be predicted from average data. It is therefore desirable to measure real ear directional benefit. This paper demonstrates a method to measure real ear hearing aid directivity based on a general approach to measure the broadband output signal-to-noise ratio of a hearing aid. Errors arising from non-linearity were tested in simulation and found to be low for typical hearing aid compression ratios. Next, the efficacy of the method to estimate directional benefit was demonstrated on KEMAR. Finally the variability of directional benefit was explored in real-ears. Significant differences in signal-to-noise ratio between directional and omnidirectional microphone settings were demonstrated at most azimuths. Articulation-Index-weighted directional benefit varied by more than 7 dB across ears at some azimuths. Such individual variation in directional benefit has implications when fitting hearing aids: it should not be assumed that all users will receive similar directional benefit from the same hearing aid.

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Using a signal cancellation technique to assess adaptive directivity of hearing aids

Cited by 8 publications

References 15 publications

Effect of Noise Reduction on Cortical Speech-in-Noise Processing and Its Variance due to Individual Noise Tolerance

Effect of Noise Reduction on Cortical Speech-in-Noise Processing and Its Variance due to Individual Noise Tolerance

Effects of a directional mic on children's word recognition and novel-word learning

Measuring real-ear signal-to-noise ratio: Application to directional hearing aids

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