Amplification - Electroacoustic Characteristics

Question 1

The outer parts of HAs vary dramatically, but on the inside they are ___ _____

Answer 1

The same

Question 2

What are the 5 steps in how an HA works?

Answer 2

1) the mic picks up the acoustic signal
2) converses it to an electrical signal
3) electrical signal is digitized then amplified
4) that signal is changed back to an electrical signal
5) then that to an acoustic signal and sent to the listeners ear

Question 3

What do the electroacoustic characteristics of the HA describe?

Answer 3

The performance characteristics - how the HA modifies the sound as its processed by the HA

Question 4

What are 2 electroacoustic/performance characteristics of the HA?

Answer 4

1) gain and frequency response

2) maximum output

Question 5

How are electroacoustic characteristics of an HA measured?

Answer 5

And electroacoustic analysis (EAA)

Question 6

What group specifies the procedures to be used in an EAA? Why is that needed?

Answer 6

The American National Standards Institute (ANSI)

Equal data/measurements from different HA companies

Question 7

Where/why can EAAs be checked?

Answer 7

At HA clinics, to make sure HAs are working like they should

Question 8

____________ sheets provided date on the _______ and _____________ charactersitcs of particular HA models

Answer 8

Specification
Features
Electroacoustic

Question 9

How are specification sheets used by audiologists? (2)

Answer 9

1) select appropriate HAs for clients

2) determine if HA is in proper working order

Question 10

What is gain?

Answer 10

How much amp the HA provides; difference between input and output

Question 11

How can gain be described?

Answer 11

With a graphic representation of gain across frequency - known as the frequency response of the HA

Question 12

The gain needed depends primarily on a persons _______ of HL

Answer 12

Degree

Question 13

Greater degree of HL = more ____ needed to make speech audible

Answer 13

Gain

Question 14

What is the general rule of thumb for the amount of gain required?

Answer 14

The gain should be about half to the degree of HL

Question 15

A person with 60 dB HL will need about ____ dB of gain?

Answer 15

30

Question 16

What is the maximum output of an HA?

Answer 16

The highest sound pressure generated by an HA regardless of input level

Question 17

All HAs have a point where increases in the _____ level do not result in additional increases in ______

Answer 17

Input

Output

Question 18

Why is a HA having a maximum output limit important?

Answer 18

If it didn’t have it loud noises would be too uncomfortable and at dangerous levels

Question 19

What are the two possible methods used to limit maximum output?

Answer 19

1) peak clipping

2) compression (automatic gain control)

Question 20

How does peak clipping work?

Answer 20

Cuts sound off it its too loud

Question 21

What is the negative of peak clipping?

Answer 21

It’s not high quality sound, causes distortion

Question 22

How does compression/AGC work?

Answer 22

Scales down the sound wave

Question 23

Which method of limiting maximum output is better/modern?

Answer 23

Compression

Question 24

Why do some clients prefer peak clipping?

Answer 24

Severe to profound HL clients may use the distraction as helpful acoustic cues

Question 25

Compression instruments very the gain applied to signals based on their _____ levels, low level inputs mean _______ gain, and vice versa

Answer 25

Input

Higher

Question 26

The maximum output of a hearing aid can be represented graphically as a ______, showing output _____ ________ ______ as a function of frequency

Answer 26

Curve

Sound pressure level

Question 27

The maximum output can be defined as the single _______ ________ on the OSPL90 curve

Answer 27

Highest number

Question 28

How is the maximum output of an HA set in large part?

Answer 28

A particular individuals tolerance for loud sounds

Question 29

And individuals Loudness Discomfort Levels (LDLs) can be measured then used to do what?

Answer 29

Set the maximum output of the HA

Question 30

When setting the maximum output you have to ensure what?

Answer 30

The maximum output is below the level that could potentially damage a listeners residual hearing