Service Manual MA 42
D-0125965 Rev. D
40
18/05/2022
AUDIOMETRY
Tone Audiometry
Tone Tests
HL, MCL, UCL, Aided
Special Tests
High Frequency Audiometry
Pure Tone Stenger
SISI Test (Automatic test: 5, 4, 3, 2, 1 dB Increment of 250 ms
every 5 s, Response Window = 1500 ms from start of increment)
Tone Decay Test (Automatic test, Duration: 60 s)
ABLB Test (Stimulus length: 500 ms or 1000 ms)
MLB Test (Stimulus length: 500 ms or 1000 ms)
Langenbeck Test (Effective masking noise: Narrow band noise)
Inputs
Sinus or warble tone (pulsed and continuous)
Outputs
Left, Right, Binaural, Bone (L+R)
Accuracy
Frequency ± 1 %
Distortion
Total Harmonic Distortion (THD): AC: < 2.5 %, BC: < 5.5 %
Precision
Level Steps: 1 dB, 2 dB or 5 dB (selectable in settings)
Stimuli
Note
: For details regarding frequencies and levels see section 6.2.
Tone
AC: Standard: 125 Hz to 8 kHz, High Frequency: 9 kHz to 16 kHz
BC: 125 Hz to 8000 Hz
Warble Tone
5 Hz sine ± 5 % modulation
Pediatric
Noise
Special narrowband noise stimulus.
The bandwidth is frequency depended: 125 Hz to 250 Hz
– 29 %,
500 Hz
– 24%, 750 Hz – 20%, 1 kHz – 17 %, 1.5 kHz – 13 %,
2 kHz 11 %, 3 kHz
– 9 % from 4 kHz and up is fix 8 %
Pulse Tone
250 ms or 500 ms on/off time (selectable in settings)
Presentation
Presenter or Interrupter
Level
AC: -10 dB HL to 120 dB HL
AC HF: -20 dB HL to 90 dB HL
BC: -10 dB HL to 85 dB HL
Insert phones: -10 dB HL to 120 dB HL
Sound field speaker with Amplifier: -10 dB HL to 115 dB HL
Safety limit: Level > 100 dB HL
Calibration
Calibration information and instructions are located in the
MA 42 Service Manual.
Speech Audiometry
Speech Tests
SRT, WRS, MCL, UCL, SRT Aided, WRS Aided
Special Tests
Speech Stenger
Master Hearing Aid (High pass filters of -6 dB, -12 dB, -18 dB, -24 dB
per octave with cut off frequency of 1 kHz, HFE filter (High Frequency
Emphasis): high pass filter of -12 dB per octave with cut off
frequencies of 1 kHz and 2 kHz, which results in -24 dB per octave)
Freiburger Speech Test (Germany only)
QuickSIN
TM
(USA only)
