Analysis of Local Cerebral Blood Flow during Exposure to Bone Conduction Sound

Bone conduction headphones enable users to listen to audio without interfering with their ability to perceive surrounding sounds. Thus, they are being increasingly adopted not only as hearing aids but also for more general purposes. Although bone conduction sound provides different perceptual characteristics compared with normal air vibrations, the detailed perceptual mechanism of bone conduction sound remains unclear. We evaluate local cerebral blood flow during exposure to bone conduction sound using near-infrared spectroscopy. Nine healthy young men (age:
$22.3\pm 0.67$
years) participated in this study. Spectroscopy probes were placed in the temporal (eight channels) and parietal (eight channels) lobes of each subject. Then, music was presented through either air conduction headphones or bone conduction headphones for 30 s. The integrated values of (de)oxyhemoglobin obtained while listening to music were compared between the headphones by applying the Wilcoxon signed-rank test. The results show that oxyhemoglobin concentration significantly increases in the parietal lobe under bone conduction compared with air conduction of sound (
$p < 0.1$
).