THEORY
OF
AMPLIFICATION
COMD 7321

NAME

HIGH SCHOOL GRADUATED FROM

DREAM CAR

SANTA CLAUS

HISTORY
AND
OVERVIEW
OF
AMPLIFICATION

1960’s

Hearing Aid Dealers

ASHA Did Not

Support

Audiologists

Dispensing

ASHA recognizes audiologists as dispensers, but...

Audiologists must:

maintain objectivity,

dispense product only as part of a comprehensive habilitation program, and

take other special steps to ensure avoiding conflict of professional interest.

Most States

Have

Licensure

Advantages to non-electric aids

provide 10-15 dB of gain in speech frequency range

allows persons with mild loss to get use to amplification

custom-made and cost <$250

no batteries

Disadvantages:

Bait and Switch Problem

Only mild gain

Transduces ________ energy to

___________ energy

Increases the __________

of the electrical signal

The ________ energy from the mic is increased by additional electrical energy from the power source

Converts ________ signal back

to _________ signal

Consisted of microphone, battery, and earphone

Provided 10-15 dB of gain in the range 1-1.8 KHz, but…..

 

Carbon Granules in the mic were pressed together and spread apart with sound pressures impinging on the mic

This movement resulted in changes in resistance which resulted in changes in current to the earphone

Limited gain, peaky response

Noisy, crackling sounds

Intermittent, sensitive to major body movements

Not flexible in tone

Consisted of a mic, amplifier, receiver and two batteries

Provided more gain and had smaller and more sensitive ____, but…..

Same 4 components

Now Head Worn

Increased _____

Soon to be replaced with Integrated Circuits, but…..

Body aids

Eyeglass aids

Ear level Aids (BTE)

Custom Aids

In-the-ear (ITE)

In-the-canal (ITC)

Completely-in-the-canal (CIC)

Bone Conduction Aids

    Internal ___________

    External___________

 

Contralateral routing of offside signal (CROS)

Cochlear implants

_____ conduction aids

Vibrotactile aids