Instruction Manual

Sound Level Meter Types 2245 –

Instruction Manual

Page 43 of 110

4.4 Reference Conditions for Acoustic Calibration

Reference Level Range: Only one level range exists and this is the reference level

range.

Reference Sound Pressure Level: 94.00 dB re. 20 μPa

Calibration Check Frequency: 1 kHz

4.5 Microphone

Microphone Type 4966:

Type: Prepolarized Free-field ½" Condenser Microphone

Nominal Open Circuit Sensitivity: 50 mV/Pa, (corresponding to –26 dB re 1 V/Pa) ±1.5

Capacitance: 14 pF (at 250 Hz)

Nominal Preamplifier Attenuation: 1.24 dB ± 0.1 dB

Microphone Reference Point: The centre of the front surface of the microphone

protection grid.

Reference Direction of Sound Incidence: See the small drawings in the lower right

corner of the directional response graphs in section 4.7.