The Healthy Ear Is a Remarkable Amplifier

Those who live with hearing loss acquired as an adult will likely express that there is nothing like normal natural hearing even with the use of today’s most advanced hearing devices.

The performance of the healthy human ear is extraordinary and awe-inspiring. Consider how the ear can sense the slight sounds of rustling leaves, the first drops of rain, and a soft whisper. We are surrounded by traveling waves of air molecules caused by objects vibrating all around us. Our ears allow us to perceive information in the very air that we breathe by amplifying the movement of air molecules through several remarkable processes:

• The hollows, folds and contours of the outer ear funnel and enhance the sound waves. (about 10 dB gain in sound)
• A resonance effect from the tube-like structure of the ear canal further boosts the high-pitched components of the traveling waves reaching the eardrum. (10-15 dB gain)
• The three small bones known as ossicles in the middle ear act as a lever system, intensifying the vibration from the eardrum before it is directed to the fluid-filled inner ear known as the cochlea. (about 34 dB gain)
• As the fluid in the inner ear is set into motion, the cochlear amplifier detects and amplifies the softest sounds. The cochlear amplifier is made up of roughly 12,000 outer hair cells attached to a membrane with special mechanical properties. The performance of these hair cells along the membrane filters and improves the signal, rewarding us with the incredible sensitivity, versatility and speed of hearing. (amount of gain to-be-determined)

Our ears are already equipped to provide phenomenal amplification. Exposure to excessively loud sounds overdrives this system, breaking the “hairs” of the hair cells and diminishing the performance of the cochlear amplifier. Rustling leaves, rain drops, and whispers become things seen but not heard

Biomedical and surgical advances can restore much of the function of the outer ear and middle ear. However, the intricate mechanic-to-electric transduction of sound from the cochlea to the brain is currently not replicable.

To continue to enjoy the wonder and beauty of good hearing, we need to conserve it and appreciate it by “turning the volume down”. When that is not possible, use hearing-protection hearing protectors to enjoy sound at safe levels.

If you have any difficulty with your hearing, visit Dr. Chris Hoffmann at Hoffmann Audiology & Hearing Aid Center in Irvine. Call at 949-536-5180 for an appointment.