When speech stimuli are presented dichotically, an advantage of the right ear (“right-ear advantage”, REA) can often be observed, which manifests itself in a better speech recognition performance compared to the left ear. Explanations for this effect often refer to a specialization of the left hemisphere for language in combination with either superior contralateral pathways (structural model) or rightward-shifts of attention induced by speech (attentional models). There is evidence that the REA is increased when cognitive load is high (Penner et al., 2009, Fumero et al. 2022). With this in mind, it is worth investigating how the REA behaves in static (constant target talker) versus dynamic cocktail-party situations (unpredictable target talker changes), as the latter are associated with higher cognitive load. Results from a previous study (Wächtler et al., 2020) indeed provided first evidence for a greater REA in dynamic relative to static situations, although ceiling effects in performance complicated interpretation of the results.

In the present study, a cocktail party situation was simulated with three competing talkers at different positions (-60, 0, and +60 degrees azimuth angle) using a matrix sentence test. The target talker was indicated using a keyword. In the static condition, the position of the target talker remained constant and was announced in advance, whereas in the dynamic situation it changed in an unpredictable manner after each trial. To avoid ceiling effects in performance, speech stimuli were either presented at low sound pressure levels or processed with a noise vocoder. Data from 16 young normal-hearing adults were included in the study.

We discuss to what extent the different cognitive demands of the two conditions (static/dynamic) influence the REA and whether there is an interaction with the type of signal degradation (low level/vocoder). Furthermore, we present the results of a detailed error analysis to investigate how far the results support structural and attentional models of the REA.

Funding: Deutsche Forschungsgemeinschaft (ME2751/3-2).

References:

• Fumero MJ, Marrufo-Pérez MI, Eustaquio-Martín A, Lopez-Poveda EA (2022). Divided listening in the free field becomes asymmetric when acoustic cues are limited. Hearing research, 416, 108444. doi:10.1016/j.heares.2022.108444
• Penner IK, Schläfli K, Opwis K, Hugdahl K (2009). The role of working memory in dichotic-listening studies of auditory laterality. J Clin Exp Neuropsychol, 31(8):959-66. doi:10.1080/13803390902766895.
• Wächtler M, Wenzel F, Kessler J, Walger M, Meister H. (2020). What are some of the challenges in dynamic cocktail party listening?. Speech in Noise Workshop 2020 (SPIN), Toulouse, France. Zenodo. doi:10.5281/zenodo.8101983