Which is mightier, the tuning fork or the bone oscillator?

Area of Science:

• Audiology
• Otolaryngology
• Biomedical Engineering

Background:

• Differentiating profound sensorineural hearing loss from mixed hearing loss is critical for cochlear implant candidacy.
• Mixed hearing loss patients, particularly those with otosclerosis or chronic otitis media, may benefit more from ossiculoplasty and conventional amplification.
• Acoustic observations suggest tuning forks may provide a stronger bone-conducted signal than standard bone oscillators.

Purpose of the Study:

• To quantify and compare the maximum bone-conduction signal intensities of tuning forks and a standard bone oscillator.
• To assess signal intensity across different tuning fork placements (forehead, mastoid, teeth) and frequencies (250, 500, 1000 Hz).

Main Methods:

• Measured maximum bone-conduction signal intensities using behavioral masking level differences.
• Tested a mastoid-placed bone oscillator and tuning forks at the mastoid, forehead, and teeth.
• Evaluated signal intensity at 250, 500, and 1000 Hz.

Main Results:

• Dental tuning fork signals significantly exceeded bone oscillator intensities at all tested frequencies (20.5 dB HL at 250 Hz, 16.5 dB HL at 500 Hz, 8.5 dB HL at 1000 Hz).
• Bone oscillator intensity surpassed tuning fork perceived levels at some frequencies when placed on the forehead or mastoid.
• A statistically significant difference (p <.001) was observed for dental tuning fork superiority.

Conclusions:

• Maximally vibrating tuning forks applied to the teeth should be used in addition to pure-tone audiometry for cochlear implant evaluations.
• Audibility of a dental tuning fork signal suggests potential mixed hearing loss, warranting consideration of alternative surgical interventions.
• This method aids in accurate diagnosis and appropriate treatment selection for hearing loss.