Better assessment of hearing loss and rehabilitation options
According to the WHO, around 466 million people, or 5 % of the world’s population, rely on rehabilitation for ‘disabling’ hearing loss. Over 90 % are adults. By 2050 it is estimated that this figure will climb to over 700 million people, or 10 %. Conventional treatment usually involves fitting a hearing aid. But some studies have estimated that as many as 25 % of owners do not use them regularly. This is largely because even with hearing aids, understanding speech in noisy situations remains problematic, and assessments for hearing aid eligibility do not typically consider realistic use scenarios. According to Sophia Kramer, coordinator of the HEAR-ECO project, “communication is also often draining for people with hearing loss, as it requires high concentration levels.” Supported by the Marie Skłodowska-Curie Actions programme, HEAR-ECO has developed objective measures of listening effort and fatigue, studying physiological indicators, such as pupillometry, electroencephalography (EEG) and cardiovascular measures, while also creating parameters to help predict effort and fatigue. “We have contributed a more comprehensive methodology to measure the consequences of hearing loss, and to assess the likely impact of hearing aids,” says Kramer, from the VU University Medical Centre, the project host. “Our science should help bridge the gap between real-world performance and lab-based testing.” HEAR-ECO’s partners included clinical audiologists, psychologists, biomedical and acoustic engineers and a partner, Oticon, the second largest hearing aid manufacturer globally.
Investigating the complexity of hearing scenarios
Speech perception is a complex task. Factors such as how important a message is to the communicator, the precise social context and acoustics, such as the presence of sound interference, all influence outcomes. “Including these aspects will ensure a more comprehensive assessment of hearing loss and rehabilitation, a significant advancement on current limited clinical tests,” adds project manager Adriana Zekveld. The project started with ‘groundwork’ studies, where each early-stage researcher (ESR) acquired expertise in a specific theme, such as cardiovascular measurements or the influence of the presence of others on speech perception, followed by work to combine these. For example, an avatar-based virtual reality system was created to simulate social situations and to study the influence of other people’s presence on speech perception, pupil response and cardiovascular measures of listening efforts. “Participants reported being affected by the presence of other avatars, both positively, making them feel more supported, or in some cases negatively, by causing distractions, for example,” remarks Zekveld. The project also reviewed the interactions between hearing aid characteristics and HEAR-ECO’s test scenarios, finding that the project’s methods provide adequate stimuli (target speech stimuli and noises) in conditions where spatial complexity and reverberation are manipulated. “This means that these more realistic test conditions can be applied to evaluate the hearing aid benefit,” Zekveld explains.
Two assessment toolboxes
The collective work of the project’s six ESRs produced two toolboxes. The first comprised methods to make speech perception tests more realistic. It incorporated social aspects, acoustic features (including user-friendly simulations, avoiding the need for expensive labs) and also means to assess motivation and fatigue. The second toolbox developed physiological indicators, with results indicating that the team’s measures were indeed sensitive to specific aspects of the listening test, such as the motivation of the listener, fatigue and the demands of memory. “As world-leading experts in this field, it is very gratifying that other research groups and several hearing aid manufacturers now incorporate measurement of listening effort into their work, with some specifically adopting HEAR-ECO’s EEG and pupillometry methods and results,” concludes Kramer.
Keywords
HEAR-ECO, hearing aid, pupillometry, motivation, fatigue, acoustics, virtual reality, EEG, speech, rehabilitation
