Listener Factors Explain Little Variability in Self-Adjusted Hearing Aid Gain

Evaluation of a semi-supervised self-adjustment fine-tuning procedure for hearing aids

OBJECTIVE

This study investigated the effects of different adjustment criteria and sound scenes on self-adjusted hearing-aid gain settings. Self-adjusted settings were evaluated for speech recognition in noise, perceived listening effort, and preference.

DESIGN

This study evaluated a semi-supervised self-adjustment fine-tuning procedure that presents realistic everyday sound scenes in a laboratory environment, using a two-dimensional user interface, and enabling simultaneous changes in amplitude and spectral slope. While exploring the two-dimensional space of parameter settings, the hearing-aid users were instructed to optimise either listening comfort or speech understanding.

STUDY SAMPLE

Twenty experienced hearing aid users (median age 69.5 years) were invited to participate in this study.

RESULTS

Adjustment criterion and sound scenes had a significant effect on preferred gain settings. No differences in signal-to-noise ratios required for 50% speech intelligibility or in the perceived listening effort were observed between the adjusted settings of the two adjustment criteria. There was a preference for the self-adjusted settings over the prescriptive first fit.

CONCLUSIONS

Listeners could reliably select their preferred gains to the two adjustment criteria and for different speech stimuli.

Preferred Strength of Noise Reduction for Normally Hearing and Hearing-Impaired Listeners

Preference for noise reduction (NR) strength differs between individuals. The purpose of this study was (1) to investigate whether hearing loss influences this preference, (2) to find the number of distinct settings required to classify participants in similar groups based on their preference for NR strength, and (3) to estimate the number of paired comparisons needed to predict to which preference group a participant belongs. A paired comparison paradigm was used in which participants listened to pairs of speech-in-noise stimuli processed by NR with 10 different strength settings. Participants indicated their preferred sound sample. The 30 participants were divided into three groups according to hearing status (normal hearing, mild hearing loss, and moderate hearing loss). The results showed that (1) participants with moderate hearing loss preferred stronger NR than participants with normal hearing; (2) cluster analysis based solely on the preference for NR strength showed that the data could be described well by dividing the participants into three preference clusters; (3) the appropriate cluster membership could be found with 15 paired comparisons. We conclude that on average, a higher hearing loss is related to a preference for stronger NR, at least for our NR algorithm and our participants. The results show that it might be possible to use a limited set of pre-set NR strengths that can be chosen clinically. For our NR one might use three settings: no NR, intermediate NR, and strong NR. Paired comparisons might be used to find the optimal one of the three settings.

Self-Adjustment of Hearing Aid Amplification for Lower Speech Levels: Independent Ratings, Paired Comparisons, and Speech Recognition

PURPOSE

Self-adjustment of hearing aid amplification enables wearers to customize the hearing aid output to match their preferences and could become an important tool for programming direct-to-consumer devices for people with mild-to-moderate hearing loss. One risk is that user-selected settings may provide inadequate audibility. This study assessed that risk by quantifying relationships between self-adjusted settings, subjective preferences, and speech recognition performance using speech at low levels in quiet, where achieving high speech audibility requires sufficient amplification.

METHOD

Fifteen people with symmetric, mild-to-moderate sensorineural hearing loss self-adjusted hearing aid amplification while listening to speech in quiet at 45, 55, and 65 dBA. After self-adjustment, 11 participants made blinded ratings of their self-adjusted fit, their NAL-NL2 prescriptive fit, and experimenter-created fits with reduced gain. Participants completed blinded paired comparisons and sentence recognition assessments using these settings.

RESULTS

The gain of self-adjusted fits showed a large range of variability between participants. On average, self-adjusted gain was similar to NAL-NL2 prescribed gain for input signals of 55 dBA and slightly greater than prescribed gain for 45-dBA signals. Speech recognition scores for NAL-NL2 fits were consistently high, and differences in speech recognition results were strongly correlated with the overall preferences obtained from paired comparisons.

CONCLUSIONS

Self-adjusted fits are highly variable between individuals for low-audibility conditions. Nonetheless, self-adjusted fits are at least as satisfactory as NAL-NL2 fits, and listeners tend to disfavor settings that result in poorer speech recognition. The findings argue against concerns that self-adjustment will result in inadequate audibility compared to prescribed settings.

Effectiveness of a Self-Fitting Tool for User-Driven Fitting of Hearing Aids

Hearing aids can be effective devices to compensate for age- or non-age-related hearing losses. Their overall adoption in the affected population is still low, especially in underdeveloped countries in the subpopulation experiencing milder hearing loss. One of the major reasons for low adoption is the need for repeated complex fitting by professional audiologists, which is often not completed for various reasons. As a result, self-fitting procedures have been appearing as an alternative. Key open questions with these digital tools are linked to their effectiveness, utilized algorithms, and achievable end-results. A digital self-fitting prototype tool with a novel quick four-step fitting workflow was evaluated in a study on 19 individuals with moderate hearing loss. The tool was evaluated in a double-blinded, randomized study, having two study aims: comparing traditional audiological fitting with the new self-fitting tool, which can also be used as a remote tool. The main reported results show moderately high usability and user satisfaction obtained during self-fitting, and quasi-equivalence of the performance of the classical audiological fitting approach. The digital self-fitting tool enables multiple sessions and easy re-fitting, with the potential to outperform the classical fitting approach.

Perceived Sound Quality Dimensions Influencing Frequency-Gain Shaping Preferences for Hearing Aid-Amplified Speech and Music

Hearing aids are typically fitted using speech-based prescriptive formulae to make speech more intelligible. Individual preferences may vary from these prescriptions and may also vary with signal type. It is important to consider what motivates listener preferences and how those preferences can inform hearing aid processing so that assistive listening devices can best be tailored for hearing aid users. Therefore, this study explored preferred frequency-gain shaping relative to prescribed gain for speech and music samples. Preferred gain was determined for 22 listeners with mild sloping to moderately severe hearing loss relative to individually prescribed amplification while listening to samples of male speech, female speech, pop music, and classical music across low-, mid-, and high-frequency bands. Samples were amplified using a fast-acting compression hearing aid simulator. Preferences were determined using an adaptive paired comparison procedure. Listeners then rated speech and music samples processed using prescribed and preferred shaping across different sound quality descriptors. On average, low-frequency gain was significantly increased relative to the prescription for all stimuli and most substantially for pop and classical music. High-frequency gain was decreased significantly for pop music and male speech. Gain adjustments, particularly in the mid- and high-frequency bands, varied considerably between listeners. Music preferences were driven by changes in perceived fullness and sharpness, whereas speech preferences were driven by changes in perceived intelligibility and loudness. The results generally support the use of prescribed amplification to optimize speech intelligibility and alternative amplification for music listening for most listeners.

Senescent Decline in Verbal-Emotion Identification by Older Hearing-Impaired Listeners - Do Hearing Aids Help?

Purpose

To assess the ability of older-adult hearing-impaired (OHI) listeners to identify verbal expressions of emotions, and to evaluate whether hearing-aid (HA) use improves identification performance in those listeners.

Methods

Twenty-nine OHI listeners, who were experienced bilateral-HA users, participated in the study. They listened to a 20-sentence-long speech passage rendered with six different emotional expressions (“happiness”, “pleasant surprise”, “sadness”, “anger”, “fear”, and “neutral”). The task was to identify the emotion portrayed in each version of the passage. Listeners completed the task twice in random order, once unaided, and once wearing their own bilateral HAs. Seventeen young-adult normal-hearing (YNH) listeners were also tested unaided as controls.

Results

Most YNH listeners (89.2%) correctly identified emotions compared to just over half of the OHI listeners (58.7%). Within the OHI group, verbal emotion identification was significantly correlated with age, but not with audibility-related factors. The number of OHI listeners who were able to correctly identify the different emotions did not significantly change when HAs were worn (54.8%).

Conclusion

In line with previous investigations using shorter speech stimuli, there were clear age differences in the recognition of verbal emotions, with OHI listeners showing a significant reduction in unaided verbal-emotion identification performance that progressively declined with age across older adulthood. Rehabilitation through HAs did not provide compensation for the impaired ability to perceive emotions carried by speech sounds.

Uni- and bilateral spectral loudness summation and binaural loudness summation with loudness matching and categorical loudness scaling

OBJECTIVE

Current hearing aid prescription rules assume that spectral loudness summation decreases with hearing impairment and that binaural loudness summation is independent of hearing loss and signal bandwidth. Previous studies have shown that these assumptions might be incorrect. Spectral loudness summation was measured and compared for loudness scaling and loudness matching.

DESIGN

In this study, the effect of bandwidth on binaural summation was investigated by comparing loudness perception of low-pass filtered, high-pass filtered, and broadband pink noise at 35 Categorical Units for both unilateral and bilateral presentation.

STUDY SAMPLE

Sixteen hearing-impaired listeners.

RESULTS

The results show that loudness differences between the three signals are different for bilateral presentation than for unilateral presentation. In specific, binaural loudness summation is larger for the low-pass filtered pink noise than for the high-pass filtered pink noise. Finally, individual variability in loudness perception near loudness discomfort level was found to be very large.

CONCLUSIONS

Loudness matching is offered as a fast and reliable method to measure individual loudness perception. As discomfort with loud sounds is one of the major problems encountered by hearing aid users, measurement of individual loudness perception could improve hearing aid fitting substantially.

Hearing Aid Self-Adjustment: Effects of Formal Speech-Perception Test and Noise

While listening to recorded sentences with a sound-field level of 65 dB SPL, 24 adults with hearing-aid experience used the "Goldilocks" explore-and-select procedure to adjust level and spectrum of amplified speech to preference. All participants started adjustment from the same generic response. Amplification was provided by a custom-built Master Hearing Aid with online processing of microphone input. Primary goals were to assess the effects of including a formal speech-perception test between repeated self-adjustments and of adding multitalker babble (signal-to-noise ratio +6 dB) during self-adjustment. The speech test did not affect group-mean self-adjusted output, which was close to the National Acoustics Laboratories' prescription for Non-Linear hearing aids. Individuals, however, showed a wide range of deviations from this prescription. Extreme deviations at the first self-adjustment fell by a small but significant amount at the second. The multitalker babble had negligible effect on group-mean self-selected output but did have predictable effects on word recognition in sentences and on participants' opinion regarding the most important subjective criterion guiding self-adjustment. Phoneme recognition in monosyllabic words was better with the generic starting response than without amplification and improved further after self-adjustment. The findings continue to support the efficacy of hearing aid self-fitting, at least for level and spectrum. They do not support the need for inclusion of a formal speech-perception test, but they do support the value of completing more than one self-adjustment. Group-mean data did not indicate a need for threshold-based prescription as a starting point for self-adjustment.

Perceptual Effects of Adjusting Hearing-Aid Gain by Means of a Machine-Learning Approach Based on Individual User Preference

This study investigated a method to adjust hearing-aid gain by use of a machine-learning algorithm that estimates the optimal setting of gain parameters based on user preference indicated in an iterative paired-comparison procedure. Twenty hearing-impaired participants completed this procedure for 12 different sound scenarios. During the adjustment procedure, their task was to indicate a preference based on one of three sound attributes: Basic Audio Quality, Listening Comfort, or Speech Clarity. In a double-blind comparison of recordings of the processed scenarios, and using the same attributes as criteria, the adjusted gain settings were subsequently compared with two prescribed settings of the same hearing aid (with and without activation of an automatic sound-classification system). The results showed that the adjustment method provided a general improvement of Basic Audio Quality, an improvement of Listening Comfort in a traffic-noise scenario but not in three scenarios with speech babble, and no significant improvement of Speech Clarity. A large variation in gain adjustments was observed across participants, both among those who did benefit and among those who did not benefit from the adjustment. There was no clear connection between the gain adjustments and the perceived benefit, which indicates that the preferred gain settings for a given sound scenario and a given listening intention are highly individual and difficult to predict.