Maturation of bone-conduction transcranial and forehead attenuation using a measure of sound pressure in the ear canal.

Objective: Although it is understood that bone-conduction (BC) hearing is different between infants and adults, few studies have attempted to explain why these differences exist. The main objective in this study was to better understand how properties of the developing skull contribute to the maturation of BC sensitivity through an indirect measurement of BC attenuation across the skull.

Design: Estimation of transcranial and forehead attenuation of pure-tone BC stimuli was conducted using sound pressure in the ear canal for a transducer placed on the skull ipsi- and contralateral to the probe ear and at the forehead.

Study Sample: Seventy-six individuals participated in the study, including 59 infants and children (1 month-7 years) and 17 adults.

Results: BC attenuation was greatest for young infants, and decreased throughout maturation. Attenuation from the forehead to the ipsilateral temporal bone was also greater compared to the transcranial measures for infants and children older than 10 months.

Conclusions: These results provide evidence that physical maturation of the skull contributes to infant-adult differences in BC attenuation. Clinicians may consider these results, in combination with previous studies using physiological measures, when fitting infants and young children with bone-anchored hearing systems.