Hearing Aid Tech

Question 1

When CIC’s are fit with insertion being more deep into the inner bony 1/3 of the external ear canal it reduced what?

Answer 1

Reduces the Occlusion Effect= more venting

Question 2

The CIC, if placed deep within the 1/3 of the Ear canal, being that the microphone is now deeply placed inside the canal it emphasizes what?

Answer 2

Higher Frequencies typically in the 2k-4K Hz range, therefore allowing for the retention of the ears ability to transmit sound within that range more efficiently.

Question 3

Occurs when the input plus the gain of the HA does not exceed the SSPL90 of the HA

Answer 3

Headroom

Question 4

What are some potential advantages of Digital Sound Processing

Answer 4

Lower noise and higher fidelity ( internal noise should be limited only by the quality of the mic and receiver)

Extensive processing capability (very specialized functions are possible)

Capability to load a variety of processing schemes into HA via Software

Question 5

Any HA that is not a true or fully digital HA is a ___

Answer 5

Analog HA

Question 6

What is a Hybrid Analog - Digital HA

Answer 6

A HA that contains a digital computer chip to control some aspect of how sound is amplified but remains in analog form

Digital components are used to control the filtering or compression characteristics

Question 7

What was The Zeta Noise Blocker?

Answer 7

A Hybrid - Digital - Analog HA that had a digital chip implemented with ITE analog hearing aid for noise reduction in the mid 1980’s

It attempted to separate speech from noise in several frequency bands using temporal differences between speech and quasi-steady state noise

It was not a success

Question 8

What is a digital programmable HA

Answer 8

AKA Digitally controlled Analog (DCA)

Unlike Zeta whose purpose was to perform filtering, the digital components are present for the purpose of programming the parameters of the HA such as Frequency Response, Gain, MPO and compression are set by attaching HA’s to computer instead of trimpots.

Question 9

What are some potential advantages to a DCA HA

Answer 9

Increased flexibility and more precise fittings of parameters such as gain, MPO and Freq Response

Can be adjusted while pt wears the HA’s

Adjustments are made without having to send back to Manufacturer and can be saved on a memory chip

Question 10

What are the 4 different types of digital memories used to store the HA parameter settings

Answer 10

RAM (Random Access Memory)
PROM (Programmable Read-Only Memory)
EPROM (Erasable Programmable Read-Only Memory)
EEPROM (Electrically Erasable Programmable Read-Only Memory)

Question 11

What can a RAM Digital Memory do?

Answer 11

Can have data written to and read from it in any random order but requires a second backup voltage supply to store the programmed parameters. Without it when turned off or battery change all instructions are lost and have to be reprogrammed

Question 12

What can a PROM Digital Memory do?

Answer 12

Allows the parameters to be stored only once requiring a physical change in the PROM chip to change HA performance.

Question 13

What can a EPROM Digital Memory do?

Answer 13

Allows the programmed parameters to be changed after subjecting the digital memory to an ultra violet light in order to erase it.

Question 14

What can an EEPROM Digital Memory do?

Answer 14

Can have data written into it, read from it and may also have new data rewritten and stored using a programming device.

Question 15

What are the four categories to a successful HA fitting (pertaining to pt)

Answer 15

Otologic Findings
Cosmetic Concerns
Performance Criteria
Financial Considerations

Question 16

Zeta Noise Blocker was:

Answer 16

An analog filter placed with a DSP Hearing instrument

Question 17

In digital signal processing a set of mathematical steps involving multiplication,addition, and subtraction is referred to as:

Answer 17

Algorithm

Question 18

Quantization is related to

Answer 18

Number of bits

Question 19

The number of bits impact the:

Answer 19

dynamic range of the hearing instrument

Question 20

Imaging occurs during the

Answer 20

Digital to analog conversion stage

Question 21

When you cup your hand behind the ear, sound

Answer 21

Increases 5-8dB

Question 22

A capacitor

Answer 22

Blocks the low frequencies and passes the high frequencies

Question 23

A resistor

Answer 23

Restricts the flow of electrons

Question 24

The function of the microphone is to

Answer 24

Convert acoustic energy into electrical energy

Question 25

Coupling in a hearing instrument refers to connecting

Answer 25

One stage of an amplifier to the next

Question 26

The T position on a HA switch can be used to

Answer 26

Amplify a telephone conversation
Couple a HA into a loop inductor system
Couple directly into the audio of a radio or TV set with a separate induction coil

Question 27

Which component can change or modify the frequency response of a HA

Answer 27

Microphone

Question 28

What is a transducer

Answer 28

Electret microphone

Question 29

Amplifiers:

Answer 29

Generate distortion

Question 30

A linear amplifier has a 1:1 relationship, this means that if you rotate the volume control on a linear aid , you change

Answer 30

The gain and the output

Question 31

Hard peak clipping occurs in a

Answer 31

Class A amplifier

Question 32

Peak rounding

Answer 32

Causes harmonic distortion above the knee

Question 33

There are two types of compression- input and output. The difference is:

Answer 33

The placement of the feedback loop