Speaker
Description
Auditory Brainstem Response (ABR) testing is currently the only clinical method for objectively determining hearing thresholds by detecting wave V of Auditory Evoked Potentials (AEPs). Its magnetic counterpart, Auditory Evoked Fields (AEFs), offers a promising alternative by identifying the sound pressure level (SPL) at which auditory responses, such as the M100, are detectable.
Whilst traditional SQUID-based magnetoencephalography (MEG) systems were applied in measurements of Auditory Evoked Fields at peri-threshold levels in some studies [1,2,3], maintenance cost and fixed sensor placement limit their use in clinical practice. Here we present results of MEG with Optically Pumped Magnetometers (OPMs), particularly the Neuro-1 integrated sensor system, with its advantages over SQUID systems, enhancing signal amplitude and reducing cost.
To study OPMs utility in assessing hearing threshold at 1 kHz, hearing thresholds of volunteers were first determined using tonal audiometry. Auditory responses to tones 3–10 dB above individual hearing threshold (dB SL, where SL stands for sensational level) were recorded with both SQUID-MEG and Neuro-1 systems in shielded environments.
Auditory M100 responses were reliably detected at 10 dB SL in both systems, with OPM-MEG providing significantly stronger M100 responses due to closer sensor proximity. The study confirms the feasibility of using OPMs for objective hearing threshold estimation and supports their use as a practical, cost-effective alternative to SQUIDs. The ease of use of Neuro-1 integrated sensor system for OPMs and lower maintenance cost is a clear advantage.
References
1. Lütkenhöner, B., Klein, J.-S., Auditory evoked field at threshold. Hearing Research. 2007; 228(1-2):188–200. doi:10.1016/j.heares.2007.02.011
2. Stufflebeam, S.M., Poeppel, D., Rowley, H.A., L. Roberts, T.P., Peri-threshold encoding of stimulus frequency and intensity in the M100 latency, NeuroReport. 1998; 9(1):91-94. doi:10.1097/00001756-199801050-00018
3. Kühler, R., Weichenberger, M., Bauer, M., Hensel, J., Brühl, R., Ihlenfeld, A., Ittermann, B., Sander, T., Kühn, S., Koch, C., Does airborne ultrasound lead to activation of the auditory cortex? Biomedical Engineering / Biomedizinische Technik. 2019; 64(4):481-493. doi:10.1515/bmt-2018-0048
