Dr. Nathan van der Stoep
Being able to locate the source of a sound is an important ability in daily life. It allows us to, for example, quickly orient towards relevant sounds in traffic or help pay attention to what a conversational partner is saying in a noisy environment. The brain combines information from two ears to determine the location of a sound source in the horizontal plane. This process of binaural interaction can be affected by asymmetrical hearing loss which distorts spatial hearing. In the Multisensory Space Lab at Utrecht University, we investigate how spatial hearing is affected by (partial) hearing loss and how we can improve sound localization after hearing loss.
Figure 1. Left: Auditory brainstem responses obtained using Chronos and BioSemi ABR EEG equipment. Right: Auditory brainstem response setup.
Previous studies have demonstrated that the amount of binaural interaction in the brainstem can be quantified by measuring auditory brainstem responses (ABR) using EEG. The amount of binaural interaction is related to the perceived location of a sound and is determined in the brainstem 5 ms after sound onset (Laumen, Ferber, Klump, & Tollin, 2016; McPherson & Starr, 1995). We started investigating how hearing loss affects binaural interaction in the human brainstem by measuring ABRs to sounds with various binaural cues (Vink, Versnel, & Van der Stoep, 2018).
Measuring ABRs requires precise timing of sound presentation and EEG markers that indicate the onset of a sound in the EEG recording. Our experiments also require custom sound presentation and stimulus randomization, so we searched for a hardware solution that provided this and was compatible with the EEG equipment we had in our lab (BioSemi ABR EEG equipment). We chose to use the Chronos in combination with E-Prime 3.0 from PST as it allows us to present a wide variety of sounds with different binaural cues in a randomized way without having to compromise stimulus timing (~0.5 ms precision).
Our studies provide new insights into the stages of auditory processing at which hearing loss affects spatial hearing and the plasticity of spatial hearing in the adult auditory system. Depending on the amount of plasticity of early auditory processing, different rehabilitation training protocols may be required to help individuals with hearing loss improve their spatial hearing abilities.
|Laumen, G., Ferber, A. T., Klump, G. M., & Tollin, D. J. (2016). The physiological basis and clinical use of the binaural interaction component of the auditory brainstem response. Ear and Hearing, 37(5), e276-90. doi:10.1097/AUD.0000000000000301|
McPherson, D. L., & Starr, A. (1995). Auditory time-intensity cues in the binaural interaction component of the auditory evoked potentials. Hearing Research, 89(1–2), 162–171.
Vink, E., Versnel, H., & Van der Stoep, N. (2018). Binaural interactions in the human brainstem in simulated asymmetrical hearing loss: A pilot study. Poster presented at the Dutch Neuroscience Meeting. [pdf]