Testing is the most important thing we do.  It defines the difference between a normal and deficient ear, and provides the knowledge to tune and dispense a hearing instrument.  Otometric testing, as described by John Victoreen, found only at Hearing Aids of Texas, concerns itself with defining the dynamic range of the deficient ear and altering/widening the range by adding loudness.  By contrast, the audiogram or medical diagnostic testing, done everywhere else, concerns itself with what caused the problem and can a doctor operate or perform a medical procedure to correct a problem.  It has no scientific or numerical relationship with hearing instruments or situations outside a doctor’s office.

Usually the audiogram will indicate that the patient has a sensorineural or nerve loss, a condition that’s not medically correctible.  Nerve loss is the deterioration of the hair cells in the cochlear or inner ear.  When the hair cells or nerve endings die, loudness sensitivity is lost, and this is what a hearing instrument replaces.

Most hearing instruments today are digitally controlled and therefore non-linear.  This means the gain or loudness added to the input (environment) varies with the loudness of the input signal.  It adds more loudness to soft, possibly inaudible inputs and raises them into the audible range.  As the input increases, the gain is reduced so they are not over amplified.  By doing this, distance from the input source is not as critical and the range of the ear is increased.

By the time a deficient hearing person “gets around” to doing something about it, when it’s “bad enough” to seek help, the gain required to make a soft high frequency sound audible, is around 30dB.  In the ear (ITE) hearing aids, the type commonly recommended, cannot supply this amount of gain, because they feedback or squeal at this level.  As in a public address system, when the microphone is too close to the loudspeaker, feedback will occur.  This is a basic flaw or weakness of all ITE type instruments.  It is also why people complain about their hearing aids because they’re not loud enough.  Living room evidence of this is that the television is still louder than where a normal hearing person would adjust it.  The only thing a hearing instrument supplies is loudness, if you don’t have enough, you won’t hear well.