Trainable hearing aids in practice: impact and application

Abstract

In clinical practice, hearing aids are typically fitted using a prescription based on average data. However, some users will request changes or fine-tuning of their hearing aid settings. Fine-tuning can be difficult in the clinic as it relies on users adequately recalling and describing the problems they experienced and the acoustic environment they were in, and on the clinician translating the descriptions to changes in hearing aid settings. Additionally, complex acoustic environments cannot easily be recreated in the clinic, leaving the user to evaluate the fine-tuned settings in their own listening environment and return to the clinic for further fine-tuning, if needed. As pressure on clinician time is increasing due to an ageing population, fine-tuning would be a clinical task which some aid users could perform themselves. Based on consistent adjustments a user makes to the settings, a trainable hearing aid can learn the user’s preferred settings and modify the settings to match the user’s preference.Previous research on trainable hearing aids concluded that the majority of users were able to train and obtain settings they preferred over the prescribed settings. To advance the field further, this project evaluated the impact of trainable aids in clinical practice; the consistency of listening preference of older adults; the time-course, outcomes and prediction of obtaining trained settings; and how users reported making adjustments to their hearing aid settings in their own listening environments.The first study was a survey of 259 clinicians and 104 adults with a hearing loss (including 81 hearing aid users) about the impact of trainable aids in clinical practice. Responses showed that over half of the clinicians activated training, and that one fifth of the users had experience with training hearing aids. Survey responses from clinicians and users with trainable aid experience were mostly positive, indicating the usefulness of trainable aids in clinical practice.The second study evaluated consistency of listening preference, as a repeatable preference is necessary for fine-tuned settings to be a reflection of the actual preference. Fifty-two participants with normal hearing or mild to moderate hearing loss selected their preference for hearing aid settings in simulated real-world environments in the laboratory. The settings differed in intensity, gain-frequency slope, and directionality. Additionally, nine psychoacoustic, cognitive and personality measures were obtained and evaluated for their predictive value of consistent preferences. Consistency of preference was variable across participants and depended on the difference between settings, the environment, and their interaction. More participants had a consistent preference for large intensity and large gain-frequency differences, and in less complex listening environments. The selected psychoacoustic, cognitive and personality measures could not predict who was more likely to obtain more consistent preferences. These findings questioned the effectiveness of fine-tuning as commonly performed in the clinic, and of successfully training hearing aids in complex listening environments.The last study was a mixed methods trial evaluating the time-course, outcomes and prediction of training when hearing aids were provided in a typical clinical context. Also, participants were interviewed about how they went about making adjustments to their hearing aid settings in their own listening environments. The 23 participants were recruited among participants who completed study two and were fitted with receiver-in-the-canal hearing aids and provided with a remote control. After 2 weeks, half of the participants who made adjustments obtained trained settings different from the prescribed, increasing to 61% after 6 weeks. There was no difference in hearing aid fitting outcomes between those who obtained trained settings and those who did not. Measures obtained in the second study could not predict who was likely to obtain trained settings. These findings suggested that training could be activated for those who can manage the user controls, and that a review of users’ progress is recommended 2 weeks after hearing aid fitting.The interviews investigating how participants made adjustments to their hearing aid settings revealed two themes: barriers and facilitators to making adjustments. Both barriers and facilitators concerned the perceived need to make adjustments, remote control use, and the difficulty or ease of making adjustments to the settings. Additionally, time to learn was a facilitator to making adjustments. Reported strategies to adjust the settings suggested that trainable hearing aid users might benefit from additional counselling about the training process, and from specific advice to make adjustments in the moment they were needed.This thesis provided new evidence about the impact and application of trainable hearing aids by providing insight into the attitudes of clinicians and adults with hearing loss towards trainable aids, the ability of adults with hearing loss to select consistent preferences when comparing different hearing aid settings, how users adjust trainable aids in everyday environments, and into the time- course and outcomes of training. Research findings overall demonstrate a need for user-driven fine- tuning and provide support for the use of trainable hearing aids in clinical practice.