gms | German Medical Science

The relation between task demand and listening effort (LE) is often assumed to form an inverse U-shape: While effort generally increases with increasing task demand (e.g., lower SNR) [1], people tend to give up (i.e., invest less effort) when a task becomes overly difficult. Another effect which increases task demand is listening through a hearing aid (HA). Strikingly, even listening through a HA in a transparent setting (i.e., gain set to 0 dB insertion gain) has been shown to have a detrimental effect on speech intelligibility for normal hearing listeners (hearing aid disadvantage) [2]. However, this finding refers to a generic and not individual transparent fitting. There is a lack of evidence whether such detrimental effects due to a transparent hearing aid develop in objective and subjective indicators of LE. We recently had devised a study (initially presented at DGA 2022) to gain new insights on how even transparent HAs can moderate the relationship of task demand (SNR) and LE [3]. The amount of LE was derived from four objective measures used in the past to reflect LE (electroencephalography, pupil size, skin resistance, and heartrate variability) and a subjective 13-level scale for subjective LE (ACALES). The intent of the initial presentation at DGA 2022 was to explore the effect of task demand and individually set transparent HAs on performance, subjective LE (ACALES) and one measure of objective LE (pupil size). Twenty-one young normal-hearing volunteers underwent a speech-in-noise task at five levels of task demand reflecting the individual speech reception thresholds from almost unsolvable SNR levels to practically fully solvable SNR levels, with and without individually fitted transparent hearing aids of 60 trials each (5 SNR x 2 HA design). In addition, we measured subjective LE using the ACALES with and without a transparent HA. Results presented at DGA 2022 showed performance differences between each of the five SNRs. Using an individually fitted transparent HA decreased both, the hearing-aid disadvantage in speech intelligibility and subjective LE. Despite the individually fitted transparent HA setting, a significant hearing-aid disadvantage remained in objective LE (i.e., increased pupil size) at medium and high task demand. Following our hypothesis, the pupil data show the inverted U-shape, i.e. the pupil decreases when the task becomes overly difficult.With this contribution, we want to compare different measures of objective LE whether they behave same or different. More precisely: We derive the occipital/parietal alpha power (one further indicator of objective LE) from the electroencephalogram, investigate the effects of task difficulty and individually set transparent HAs, and compare these results to existing pupil results (presented at DGA 2022).