What it is
Depending on the acoustic situation and the context, listening can require more or less attentional and cognitive processing. This dynamic activity of the brain which accompanies and enables listening is ongoing and cumulative. And it happens regardless of how much of the speech is actually understood. Hearing loss degrades our ability to perceive the speech signal, thereby increasing the demands on cognitive resources involved in selectively attending and interpreting it. The increase in cognitive activity needed for the compensation of missing speech details in difficult listening situations is experienced as effortful listening and will eventually lead to listening fatigue. In other words, listening effort is more than just understanding speech, it’s about how easy it is to understand.
How it is measured
Previously, hearing effort has been primarily measured using questionnaires, rating scales and individual measurements recorded after the hearing test. Because these methods are subjective, they were often found to be inaccurate. We use an objective method which would enable us to judge the success of a hearing aid feature in rendering the listening experience more comfortable in the short (immediately) and long term (at the end of the day), in different speech recognition situations. We use an objective method for measuring listening effort based on the EEG oscillatory potential recordings. Electroencephalography (EEG) is an electrophysiological monitoring method to record electrical activity of the brain. It is typically noninvasive, with the electrodes placed along the scalp. For our purpose of measuring listening effort, we record trains of electrical events produced by the brain during the speech recognition test. Then we use up-to-date mathematical models to interpret the recorded EEG data (references to KeyNumerics) to derive an objective evaluation of listening effort. By monitoring ongoing EEG, we are able to measure listening effort in real-time while the actual speech recognition tasks are being conducted. These measurements are then averaged across several tasks to obtain representative results. It is with this objective measurement that we are able to clinically prove primax to be able to reduce listening effort for the wearer in a wide variety of situations.
primax reduces listening effort
Clinical studies conducted at the University of Northern Colorado using the methodology discussed above have already shown that primax hearing aids reduce listening effort in both noisy environments and in reverberant conditions.* Four more studies partnered with key opinion leaders in audiology are underway to provide even more clinical proof for the effectiveness of primax hearing aids in reducing listening effort.
* Study conducted at the University of Northern Colorado examined the effectiveness of the new features of primax by collecting and analyzing ongoing EEG data while subjects performed speech testing. For both primax features SPEECH and EchoShield, the objective brain behavior measures revealed a significant reduction in listening effort when the feature was activated (Littmann, Froehlich, & Beilin. Objective listening effort assessment: The benefit of primax. Sivantos Whitepaper, Jan. 2016).