Technology Update SessionSession 1D Today, we routinely diagnose and adjust hearing aids primarily to manage audibility. In clinical practice, there is no systematic testing of hearing in noise once audibility is restored. However, even with hearing-aid amplification, many individuals still find it challenging to understand speech in noisy conditions. This has been established since the 1940's, with many following studies recommending the use of speech-in-noise testing in audiological practice. Although such best practice recommendations are now well known, less than 50% of hearing care professionals currently use speech-in-noise testing, due to many practical barriers. Importantly, even when speech-in-noise testing is used as a diagnostic tool, there is no evidence-based approach to adjust help-in-noise hearing-aid settings based on the result. Typically, hearing aid users are initially given default settings, with subsequent adjustments made subjectively and often reassessed through a trial-and-error process.We present the Audible Contrast Threshold (ACT) diagnostic test, a quick, reliable, and language-independent method to evaluate a person's aided speech-in-noise ability prior to hearing-aid fitting. The ACT test measures the ability of a patient to detect spectrotemporal modulations (STMs). STMs are inherent to speech signals and essential cues for speech processing in the auditory system. In the ACT test, STMs are applied to a non-speech stimulus. The smallest degree of modulation a person can detect is measured and can be used as a proxy of speech-in-noise ability once audibility has been compensated for. This way, a person with a good ACT value is expected to distinguish speech from background noise as easily as a normal-hearing person, even with minimal contrast. Conversely, a person with a poor ACT value is expected to require a larger contrast to understand speech in noise.This talk reviews the scientific studies that, over the past decade, have optimized the STM detection paradigms from academic research to create a clinically viable diagnostic test that could easily become part of a standard clinical flow. This was achieved by introducing several modifications to the test procedure, stimulus characteristics, and stimulus presentation mode. Importantly, frequency-specific shaping of the stimulus was introduced in each ear to ensure its full audibility. The ACT test was designed to resemble pure-tone audiometric testing as much as possible, using the same equipment and threshold tracking procedure, as well as a dB result scale normalized to normal-hearing performance.Once the final version of ACT was designed, international clinical studies with hearing-aid users confirmed the strong correlations between ACT and speech-in-noise ability observed in earlier academic research. The test's utility in guiding the prescription of beneficial levels of help in noise in hearing aids was also demonstrated, along with its excellent reliability. The results of the clinical studies were used to define a first prescription rule for hearing-aid help-in-noise settings, providing audiologists with an evidence-based personalization of the additional contrast between speech and noise the hearing aids should create. The ACT test is a reliable tool to directly address, in the diagnostic, fitting, and counseling processes, the number-one complaint of people with hearing loss: hearing in noise.
|