Real-life ear-EEG Recordings of Auditory Responses to Ambient Sounds

Abstract

Despite being one of the most researched neural responses, auditory potentials have primarily been measured in controlled laboratory environments. However, there is a big interest in measuring auditory potentials in more naturalistic environments, with stimuli resembling, to a higher degree, natural sounds. The objective of this study is to investigate auditory evoked potentials elicited by naturally occurring sounds in real-life environments. The paper presents an integration of a portable hearing aid research platform and a portable ear-EEG platform. This setup was validated through recordings of an Auditory Steady State Response (ASSR), elicited by real-time amplitude modulation of the ambient sound at 40Hz. Recordings were conducted in real-life under three conditions: walking and sitting with open and closed eyes. In addition to ear-EEG, scalp EEG was recorded as a reference. For analysis, EEG signals were categorized into three groups: scalp channels, cross-ear channels, and within-ear channels. For each condition and channel group, the signal-to-noise (SNR) of the ASSR was calculated. The ASSR was statistically significant across all channel groups and conditions. A post-hoc analysis assessed the recording duration required to obtain a significant ASSR, revealing that 10 minutes were enough for within ear ear-EEG for all but two cases, whereas less than 7 minutes were sufficient for all but one case when using scalp-EEG. Clinical relevanceThe Auditory Steady-State Response (ASSR) is a versatile tool for assessing various characteristics of the auditory pathway. The ability to measure ASSR in real-life conditions using ambient sound could facilitate the development of hearing aids capable of dynamically adapting to the users current hearing loss.