Fitting Verification Flashcards
What is a free field
A large outdoor area with no surfaces to reflect sound. An anechoic chamber approximates a free field without reflections or echoes
Because sound speech measurements approximate real life situations, how should they be tested when verifying
They should be tested in a sound field rather than a controlled environment like a sound booth and the speaker placement should be at 0 degrees and 1 meter
ANSI standards add how many dB to convert speech from HL to SPL
Add 20dB
You subtract 20dB if you use the audiometer circuit in sound field
What does 10dB S/N mean
Means the words are 10dB louder than the background noise.
When a probe microphone tip is used in the ear canal, what does functional and use gain become
Insertion Gain
The signal/Noise ration of a HA response is
The difference in decibels between the signal and the noise in the system
Acoustic gain is measured in:
Decibels SPL
High frequency Average (HFA) full on gain is measured by averaging the gain at:
1000,3000 and 4000 Hz
High Frequency Average SSPL,90 (HFA SSPL 90) refers to
High frequency average saturation sound pressure level with a 90dB SPL input
The Saturation Sound Pressure level should:
Directly relate to the clients UCL
ANSI standards can compare:
One instrument to another
The SSPL 90 curve measures
All the tones across frequency
All ANSI Intrument measurements are
SPL
Input sound pressure is measured:
At the microphone opening of the hearing instrument
Gain control is another name for
Volume wheel
Basic verification involves
Checking MCL and UCL in quiet and noise
Verification procedures
Check the accuracy of your fitting
An effective verification is
A measurable improvement in communication
Functional Gain of the instrument
Is one method of fitting verification
Speech tests measured through the audiometer circuit
Are 20dB less because of ANSI Standards
Ideally, when presenting recorded words in noise
The words are 10dB louder than the noise
Sound field is
A controlled environment
Most Pt’s use enough gain in the HA to understand quiet speech at a level of
55dB SPL
When UCL’s are not balanced, a loud signal is perceived as
Lateralizing to the ear with the higher output
The following measurements use SPL, as a reference
Probe microphones
Sound field thresholds
ANSI specifications
