Using a Bone Conduction Hearing Device as a Tactile Aid

Abstract

Background: With the advent of cochlear implants, tactile aids for the profoundly deaf became obsolete decades ago. Nevertheless, they might still be useful in rare cases. We report the case of a 25-year-old woman with Bosley–Salih–Alorainy Syndrome and bilateral cochlear aplasia. Methods: After it was determined that cochlear or brainstem implants were not an option and tactile aids were not available anymore, a bone conduction device (BCD) on a softband was tried as a tactile aid. The usual retroauricular position and a second position close to the wrist, preferred by the patient, were compared. Sound detection thresholds were measured with and without the aid. Additionally, three bilaterally deaf adult cochlear implant users were tested under the same conditions. Results: At 250–1000 Hz, sounds were perceived as vibrations above approximately 45–60 dB with the device at the wrist. Thresholds were approximately 10 dB poorer when placed retroauricularly. Differentiation between different sounds seemed difficult. Nevertheless, the patient uses the device and can perceive loud sounds. Conclusions: Cases where the use of tactile aids may make sense are probably very rare. The use of BCD, placed, e.g., at the wrist, may be useful, but sound perception is limited to low frequencies and relatively loud levels.

Soft Tissue Conduction Activates the Auditory Pathway in the Brain

“…The result that the subjects comprehended the spoken words provides evidence that they heard and understood the words, and then their recitation (recognition and repetition of the words) provides convincing evidence that the auditory pathway and cortex are involved, and this is the major advantage and contribution of the present study. However, the somatosensory system was likely also activated at the same time by the low-frequency components of the speech stimuli delivered by the vibrator to sites on the body, though without activation of the auditory nerve and brain auditory pathway, as reported in [13]. A future study could also include the evaluation of responses to 125 and 250 Hz of vibratory stimulation (however, only after providing sufficient output intensity at these frequencies) in order to enable better comparison of the tactile and auditory systems.…”

“…A future study could also include the evaluation of responses to 125 and 250 Hz of vibratory stimulation (however, only after providing sufficient output intensity at these frequencies) in order to enable better comparison of the tactile and auditory systems. The audio-tactile integration or substitution studies which combine auditory with tactile stimulation [11][12][13] have led to the development of audio-to-tactile sensory substitution devices which transform the low-frequency components of speech signals into tactile vibrations delivered, for example, to the finger tips. The results of such studies showed immediate and robust improvement in speech and were able to enhance otherwise inaudible tones in the specific range of frequencies of the Pacinian corpuscles (200-350 Hz).…”

“…Therefore, in studies involving STC stimulation in response to extrinsically induced body vibrations which are to be detected behaviorally by the subjects, there is the possibility that the subjects may "detect" the presence of the vibrations by means of their cutaneous mechanoreceptors and somatosensory pathway in the spinal cord, brainstem and cortex. This is especially relevant in light of the attempts to assist patients with hearing loss by the use of audiotactile integration or substitution [11][12][13], that is, by delivering auditory stimuli coupled with tactile stimuli, making use of the communications between the somatosensory and auditory neural pathways.…”