Note: As the sound pressure level of the white noise signal will be quite high even for moderate attenuator settings, a
warning sign will be displayed in OTOsuite when appropriate (for levels above 100 dB HL).
Table 1 - Offset from Effective Masking Level to Sound Pressure Level
Frequency (Hz) 125 250 500 750 1000 1500 2000 3000 4000 6000 8000 9000 10000 11200 12500
Offset (dB) N/A* 53 37 32 31 29 30 29 27 31 27 26 26 25 25
This table indicates the number (“Offset”) to be added to the displayed masking level in order to calculate the sound pres-
sure level in dB SPL.
* White masking noise is not available at 125 Hz
Table 2 - Attenuator settings required to obtain a white noise level of 80 dB SPL
Frequency (Hz) 125 250 500 750 1000 1500 2000 3000 4000 6000 8000 9000 10000 11200 12500
Attenuator setting to
obtain 80 dB SPL
N/A* 27 43 48 49 51 50 51 53 49 53 54 54 55 55
This table indicates the attenuator settings required to obtain a sound pressure level of 80 dB SPL at indicated frequencies.
Stimulus modulation
FM (Warble): Adjustable modulation rate and depth
• Modulation rate: 1-20 Hz (default: 5 Hz).
• Modulation depth: 1-25% of center frequency (default: 5%).
SISI: 5, 2, 1 dB increments
Accuracy of sound level
Entire level range (AC): 125 to 5000 Hz: ±3 dB, 5000 to 12500 Hz: ±5 dB
Entire level range (BC): 250 to 5000 Hz: ±4 dB, 5000 to 8000 Hz: ±5 dB
The reference conditions for the specification of frequency response and sound pressure level depend on the type of audi-
ometer. AURICAL Aud can be calibrated as either a “corrected” (Type AE) or “uncorrected” (Type A) speech audiometer:
Type AE calibration:
• The output sound pressure level and frequency response are specified in terms of free-field equivalent sound pressure
level.
• The loudspeaker output is specified as measured under free-field conditions, at 1 m distance, and on the axis of the
loudspeaker.
• Bone vibrator output is not corrected to obtain a free-field equivalent sound force level; uncorrected output is pro-
duced (please see below under “Type A”).
• Calibration of speech signals is performed using either a 1 kHz pure tone (earphones) or 1 kHz warble tone (loud-
speakers).
22 Otometrics - AURICAL Aud
17 Technical specifications
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