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

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.