CHRONIC ILLNESS: HEARING LOSS AND DEAFNESS

Chronic Illness: Hearing Loss and Deafness



Chronic Illness: Hearing Loss and Deafness

Introduction

Language defines us as human. Hearing is how we learn speech. As we learn our language as children, we use that language to organize how we see the world. Hearing is how we best receive the speech sounds that contain the ideas, feelings, and personalities of other humans. The structures, which accomplish this task, include the outer ear, the ear passage, and the eardrum and bony chain. The next phase of hearing involves the hair cell array in the organ of Corti of the cochlea, which analyses the waves and converts them into the complex digital code carried by the nerve of hearing to the brain. Additional stages of hearing include the brain which constantly adjusts the cochlea depending on what we intend to hear. Our ears exhibit miraculously sensitivity.

Inner Ear Sensitivities

The conduction mechanism of the first stage, at the threshold of hearing for a 1000 Hz tone moves a distance of 1/10th the diameter of a hydrogen atom. We perceive the movement as sound.

Mode

Lowest Reported Threshold

Auditory

10-4 dyn/cm2 peak sound pressure

Seismic

5 X 10-4 cm/sec2 peak acceleration

Rotational

0.04 deg/sec peak velocity

Gravity

5 cm/sec2 lineal acceleration

Disorders of the ear may affect either or both stages. The two over all types of loss are:

conductive.......caused by problems affecting the first stage of sound processing

nerve loss.........resulting from malfunctions in the second and later stages

Conductive Losses

Conductive losses are caused by anything interfering with the first stage of sound processing. Conductive losses make the sounds seem faint or distant. When the sound source is made louder, the hearing loss is completely overcome. Often the hearing loss is accompanied by a feeling of blockage.

Common causes include:

wax in the outer ear passage

fluid in the middle ear

Other conditions include otosclerosis which jams the bony linkage between the ear drum and the inner ear, or ear drum/bony chain damage from chronic infection.

Conductive losses almost always can be repaired by either medicine, surgery or a combination.

Nerve Hearing Loss

The structures involved in a nerve hearing loss (otherwise called 'sensorineural' or 'perceptive') include the cochlea and eighth cranial nerve, are locked away inside the bones at the bottom of the skull. The sounds of language are coded in high frequencies and in the low frequencies. When normal hearing people have difficulty hearing speech sounds in the low frequencies, they figure them out ...