Lecture 5: Electroacoustic Measures Flashcards
1
Q
What is the purpose of EA Measurements?
A
- Measurement in controlled environment
- Real time
- Compare with specifications
- Performance over time
- Verify after programming
- Suitability for the individual
- Hearing aid failture
2
Q
What equipment is used for EA measurements?
A
- Solid dense walls
- Absorbment materials inside
- 2 speakers
- Test microphone (coupler microphone)
- Reference microphone
3
Q
What is a coupler?
A
- A metal assembly that couples the output of the hearing aid to the microphone of the electroacoustic system (takes the place of the ear)
- Different types of couplers for different kinds of hearing aids
- Coupler is used for in the box testing
4
Q
What are the measurement signals (2)?
A
Pure tone sweep
Broadband signal
5
Q
What are the equipment standards?
A
- Anechoic chamber, sound source and microphone must be periodically calibrated to ensure accuracy
- Must maintain standard operating conditions
- Appropriate coupler must be used
6
Q
List and describe the different EA measurements.
A
- See info. from lecture *
7
Q
What are the advantages of EA measures?
A
- Real-life settings
- Processing of stimulus that resembles natural speech
- Visibility of compression effects
8
Q
What are the limitations of functional gain measures?
A
- Subjective measure
- Cannot create small changes <10 dB
- Time consuming
- More gross frequency response increments
- Cannot measure effects of varying input level on output
- Cannot measure saturated sound pressure level in the ear
9
Q
What are the advantages of REM?
A
- Objective measure
- Measures changes as small as 1 dB
- We can always measure things like: compression features, max output, venting effects, occlusion, and directional microphone performance
- Much faster
10
Q
What is REUR or REUG?
A
Real Ear Unaided Response or Real Ear Unaided Gain
- Describes the acoustic transformation from the SF to the TM
- May be altered by ME pathology or surgery
- REUG refers to SF outside the ear (ear canal SPL - input SPL)
11
Q
What is REAR?
A
Real Ear Aided Response
- The response of the hearing aid measured at or near the TM
- Evaluate smoothness of response in the ear
12
Q
What is REIG?
A
Real Ear Insertion Gain
REAR - REUR = REIG
or
REAG - REUG = REIG
- indirect measure
- used to compare with the prescriptive target
13
Q
What is REOR?
A
Real Ear Occluded Response
- SPL at or near the TM with HA in place but turned off
- Useful for checking vent resonance
- A peak in the REOR can cause a dig in the REAG
- Patient complains of loudness or sound quality of their own voice (occlusion effect)
- Can measure effectiveness of venting changes/shell changes with this measure
14
Q
What is RESR?
A
Real Ear Saturation Response
- HA output with loud input (estimation of max output)
- Used to verify that HA output does not exceed LDLs
- Not defined by ANSI standard
- Measured values of RESR depend on the bandwidth of the signal
15
Q
What is RECD?
A
Real Ear-to-Coupler Difference
- Difference between sound measured in coupler & sound measured in ear canal
- Affected by ME pathology
- Not defined in ANSI standard
