amplifying technology

Question 1

prescription hearing aids, self fitting OTC Hearing aids, and pre-set OTC hearing aids fall in what category ?

Answer 1

FDA Regulated Devices: intended for individuals w/ hearing loss

Question 2

personal sound amplyfing devices, hearables and consumer audio devices (HAT, etc) fall in what category ?

Answer 2

Not FDA Regulated Devices: intended for ppl w/ normal hearing

Question 3

OTC hearing are for what kinds of HL?

Answer 3

people who PERCIEVE a mild to moderate hl
we dont fit but we repair

Question 4

db input + db gain = ???

Answer 4

db output

Question 5

what is input ?

Answer 5

The INTENSITY of the acoustic signal entering the device
-Ex. mic or ear

Question 6

what is gain

Answer 6

The amount of AMPLIFICATION added to the input signal

Question 7

what is output?

Answer 7

The INTENSITY of the signal that’s delivered into the ear canal

Question 8

how may input appear in programming software?

Answer 8

May appear as dB values or as a loudness descriptor in programming software
Soft/50 dB; Moderate/65 dB; Loud/80 dB

Question 9

what db levels are considered as soft db inputs?

Answer 9

40-50 db

Question 10

what db levels are considered as a moderate input level?

Answer 10

65 db

Question 11

what db levels are considered as a loud input level?

Answer 11

75-80 db

Question 12

how does gain appear in software programming ?

Answer 12

Equals the dB added to each frequency range and input level
-in the graph on the side it’s the amount of additional input you are adding

Question 13

how does output appear in software programming

Answer 13

Equals the intensity arriving to the tympanic membrane (TM)
it’s the intensity coming to the t.m

Question 14

in this class, when we use db, what does it represent ?

Answer 14

DB SPL

Question 15

when is db HL used ?

Answer 15

ONLY WHEN TESTING AUDIOGRAMS

Question 16

when do we use db SPL?

Answer 16

we use it in everything else when were not testing audiograms

Question 17

when is audiometric data converted from HL to SPL?

Answer 17

it’s converted before we’re going to fit amplification

Question 18

the audiometric data is conversion is based on what?

Answer 18

This conversion is based on the size of the average adult ear

Question 19

what is an important factor to remember when we’re going to start to fit devices

Answer 19

are all ears the same size?

Question 20

in the acoustic ear, what did people use?

Answer 20

-happened from the 13th to 19ht century (the 1st era)
- they didn’t have ELECTRIC amplification so the used physical ways to increase signal intensity

Question 21

what was the acoustic horn principle ?

Answer 21

-Horns amplify sounds when waves are reflected into a progressively narrower area, thereby increasing the sound pressure level that reaches the ear ***
it focused on amplification
-They increase sound directionality
-caused distortion
-All frequencies are equally amplified
-cant control amplifications between low and high freq
-The intensity of an acoustic signal changes as it travels through a horn

Question 22

what was the first acoustic horn ?

Answer 22

hand cupping

Question 23

how many db gain did hand cupping contribute to the signal?

Answer 23

-It added +5 -10 dB of gain to the input signal in mid to high frequencies
-It increased gain of acoustic signals arriving from the front
-It attenuate acoustic signals arriving from the rear

Question 24

what does the length and size of the horns opening determine?

Answer 24

-The length and size of a horn’s opening determines the final output intensity and which frequencies are amplified
-Increased length of the horn increases the SPL energy transferred to ear
-The wider opening collects more sound
-The combination of increased length & wider openings maximizes gain added to the input signal
-the longer the horn the longer the amp

Question 25

what does frequency responses compare ?

Answer 25

Frequency response curves compare the intensity of the input signal to either the added gain, or final output of a device

Question 26

what happens when amplitude output increases ?

Answer 26

Amplified output increased when the speaking tube length increased

Question 27

what did the carbon era contribute to?

Answer 27

The 1st “electric” hearing aids used a carbon microphone and a receiver; © 1902

Question 28

what did the carbon era convert ?

Answer 28

-Carbon microphones collected the acoustic signal & converted it into an analog (identical) electric signal - The receiver then converted the analog electric signal back to an acoustic signal

Question 29

electric hearing aids convert what to what?

Answer 29

Electric hearing aids convert an acoustic signal into an analogous electric signal

Question 30

the receiver converts what to what

Answer 30

The receiver converts the analogous electric signal back to an acoustic signal

Question 31

what don't carbon hearing aids contribute?

Answer 31

Carbon hearing aids didn’t have amplifiers to add gain to the acoustic input signal

Question 32

resonance reflector positioned behind the mic adds how much gain to the signal input

Answer 32

-“Resonance-reflectors” positioned behind the microphone added 5-10 dB SPL of gain to the input signal b/w 1k Hz to 3.5k Hz -Microphones were stacked on top of one another to add more gain

Question 33

the vacuum tube era contributed to what

Answer 33

The invention of the vacuum tube amplifier added gain to increase the amplitude of the analogous electric signal. Increased gain resulted in increased acoustic output.

Question 34

The transitior era contributed to what?

Answer 34

-A transistor is an electrical component used to increase current flow of electronic signals (increases amplitude) -A resistor is an electrical component used to add or remove resistance to the flow of electrical current (modifies frequency response or output)

Question 35

what do todays device contribute in terms of transistor era ?

Answer 35

Today, devices combine multiple transistors & resistors into a single component referred to as “integrated circuits

Question 36

what is integrated circuit?

Answer 36

Integrated circuit: an electronic circuit formed on a small piece of semiconducting material, performing the same function as a larger circuit made from discrete components.

Question 37

what do transistors and resistors allow?

Answer 37

Transistors & resistors allowed modification of gain & output signals!

Question 38

what do transistors conduct ?

Answer 38

they conduct the electrical signal

Question 39

what do transistors do in a hearing aid?

Answer 39

-In a hearing aid it amplifies the amplitude of a signal -i.e., amplifiers, take a tiny electric current at one end (analog electric current) and produces a much bigger flow of electric current at the other (output current)

Question 40

transistors can act like what in hearing aids?

Answer 40

Connected transistors can act as logic gates carrying out decision making in hearing aids. 

Question 41

Resistors conduct what ?

Answer 41

the electrical sine signal

Question 42

what are resistors used for ?

Answer 42

 -It’s used to modify the output, frequency, or intensity in some way -i.e., filter all the low frequencies signals and don’t let them pas through the circuit

Question 43

what is a potentiometer?

Answer 43

-A small resistors control used to modify the output signal in early analog hearing aids. -Manipulated the output signal, frequency response, the amount of gain added, & the compression ratio -AKA- “Trimmer pot”, or “pot screw”