The goal of this observational study is to learn about the sound-induced vibration level of certain structures in the middle ear in the normal-hearing population. The targeted structures are part of a chain of structures responsible for conducting sound within the auditory system and so their ability to vibrate normally in response to sound is relevant to the diagnosis of conductive hearing loss.

The main questions the study aims to answer are:

• What are the mean and variance of the normal sound-induced vibration level at two anatomical locations, the umbo of the malleus and the tip of the incus?
• Are there any significant differences in these vibrational responses associated with sex or age?

Participants will have their ossicular mobility measured with an investigational medical device that sends light into the middle ear and measures the motion-induced phase shift on light reflected from the target structures when a sound stimulus is presented. Standard hearing tests including audiometry and tympanometry will also be performed to confirm the normal hearing status of participants.

Inclusion Criteria:

• Normal-hearing
• Over the age of 18
• At least one of incus or umbo visible under otoscopic examination
• Type A 226Hz tympanogram with peak static compliance occurring at pressure between -99mmH20 and +50mmH20 and peak static compliance in the range from 0.3 to 1.6 cc

Exclusion Criteria:

• Audiometric air conduction thresholds greater than 40 dBHL at 500 Hz, 750 Hz, 1000 Hz, 1500Hz, 2000 Hz, 3000 Hz
• Audiometric air bone gap greater than 5dB at 500Hz, 750Hz, 1000Hz, 1500Hz, 2000Hz and 3000Hz
• Self-reported history of ear infection in the previous 3 months
• Self-reported history of middle ear surgery in the last 5 years
• Self-reported history of tympanic membrane perforation within the last 5 years
• Self-reported medical treatment for any ear-related disorder within the last 5 years
• Evidence of perforation, tympanosclerosis, otitis externa, thickened or fibrotic eardrum, mycosis, fluid, infection or other ear abnormality under otoscopy

Minimum 120 normal-hearing subjects including at least 10 male and 10 female subjects in each age group 18-30, 30-40, 40-50, 50-60 and 60+