Ito T, Röösli C, Kim C J, Sim J H, Huber A M, Probst R
Department of Otolaryngology, Head and Neck Surgery, Yamagata University Faculty of Medicine, Yamagata, Japan.
Audiol Neurootol. 2011;16(1):12-22. doi: 10.1159/000314282. Epub 2010 May 7.
Vibratory auditory stimulation or bone conduction (BC) reaches the inner ear through both osseous and non-osseous structures of the head, but the contribution of the different pathways of BC is still unclear. In this study, BC thresholds in response to stimulation at several different locations including the eye were assessed, while the magnitudes of skull bone vibrations were measured on the front teeth in human subjects with either normal hearing on both sides or unilateral deafness with normal hearing on the other side. The BC thresholds with stimulation at the ipsilateral mastoid and ipsilateral temporal region were lower than the BC thresholds with stimulation at the other sites, as reported by previous works. The lower thresholds with stimulation at the ipsilateral mastoid and ipsilateral temporal region matched higher amplitudes of skull bone vibrations measured on the teeth, but only at frequencies below 1 kHz. With stimulation at the eye, the thresholds were significantly higher than those with stimulation at the bony sites in the frequency range of 0.25-4 kHz. While skull bone vibrations as measured on the teeth during stimulation at the eye were low for low frequencies, significant bone vibrations were measured at 3 and 4 kHz, indicating different pathways for BC for either the soft tissue or bony site stimulation. This finding contradicts a straightforward relationship between vibrations of the skull bones and BC hearing thresholds.
振动听觉刺激或骨传导（BC）通过头部的骨性和非骨性结构到达内耳，但骨传导不同途径的作用仍不清楚。在本研究中，评估了在包括眼睛在内的几个不同位置进行刺激时的骨传导阈值，同时测量了双侧听力正常或一侧耳聋而另一侧听力正常的人类受试者前牙处颅骨振动的幅度。如先前研究报道，同侧乳突和同侧颞区刺激时的骨传导阈值低于其他部位刺激时的骨传导阈值。同侧乳突和同侧颞区刺激时较低的阈值与牙齿上测量到的较高颅骨振动幅度相匹配，但仅在1kHz以下的频率。在眼睛处进行刺激时，在0.25 - 4kHz频率范围内，阈值显著高于在骨性部位刺激时的阈值。虽然在眼睛处刺激时牙齿上测量到的低频颅骨振动较低，但在3kHz和4kHz时测量到明显的骨振动，表明软组织或骨性部位刺激的骨传导途径不同。这一发现与颅骨振动和骨传导听力阈值之间的直接关系相矛盾。
