Instruction Manual

Sound Level Meter Types 2245 – Instruction Manual Page 46 of 110
4.6.3 Acoustical Frequency Responses
All the acoustical frequency responses are given for Z frequency weighting.
The A-, B- and C-weighted acoustical frequency responses can be found by adding the
appropriate response from the “Add to Acoustical Responses” columns of Table A.1 to
the Z-weighted responses.
4.6.4 Free-field Frequency Responses
The free-field frequency responses for plane progressive sinusoidal sound waves
incident from the reference direction with Z frequency weighting are provided in Fig.
4.3 to Fig. 4.4 and Table A. 2 to Table A. 3. The tables also provides the ‘Expanded
Uncertainties of Measurement’ required by IEC 61672–1, see the start of section 4.6.
Fig. 4.3 Free-field 0° frequency response for the sound level meter. Corresponds
to the “Acoustical Response” column in Table A. 2
Fig. 4.4 Free-field 0° frequency response for the sound level meter with
Windscreen UA-1650. Corresponds to the “Acoustical Response” column in
Table A. 3.
4.6.5 Diffuse-field Frequency Responses
The diffuse-field frequency responses (also called random-incidence frequency
responses) with Z frequency weighting are provided in Fig. 4.5 to Fig. 4.6 and Table A.
4 to Table A. 5.