Research shows that background noise affects how well people perceive speech. When we listen to someone speak, other conversations or background sounds increase the signal-to-noise ratio (SNR). As the SNR increases, it becomes proportionally difficult to comprehend the words of the speaker we are trying to pay attention to.

EPOS conducted a study aimed to examine the effect of passive damping technology (attenuation) on speech intelligibility and listening effort. Investigation was also conducted into if such effect may change after performing high cognitive demand tasks.

In brief, the study measured speech intelligibility in noise and listening effort with and without passive damping technology activated before and after a cognitive load block. Both objective and subjective measured are used.

EPOS BrainAdapt

Test Metrics

A total of nineteen Danish speakers, eight females and eleven males with an average age of 36, who reported to have normal hearing took part in the study.

The test environment was controlled for noise and light levels to maintain consistency between participants.



The results of this study have been presented and reviewed at scientific conferences including the International Hearing Aid Research Conference (IHCON) 2022, Lake Tahoe, USA and the International Conference on Cognitive Hearing Science for Communication, Linköping, Sweden.

Overall, the results confirm that passive noise damping has a quantifiably positive effect on speech intelligibility and required listening effort. The magnitude of this positive effect does not change after performing a cognitive demand task.

Researchers could measure and quantify what level of passive noise damping creates the optimal effect, supporting improved cognition and memory, while minimising fatigue.

The task which tracked pupil dilation as a proxy for listening effort showed results that were consistent both subjectively and objectively. This means that the test subjects’ own appraisal of their performance generally matched the results of the pupillometry.

The damping made a noticeable difference in the participants’ performance. This reflected in the measurement of 35% less listening effort required by the test subjects when listening through the EPOS headsets.

In the listening comprehension test, subjects were asked to listen to a set of speech material with varying levels of competing background noise. When listening though the EPOS headsets, the participants displayed levels of up to 20% higher word recognition, with an average of up to 10% better memory recall.

This study has been crucial in further optimising the performance of EPOS headsets that built on EPOS BrainAdapt technology.

For the full study test metrics, statistics and data, head on over to the Scientific Whitepaper 2022 – “The effects of noise attenuation on listening effort and arousal”.