Product data

4
Press the Save pushbutton to save the measurement (see Fig. 5, right). You are now ready to measure at
position 2.
Fig. 6
Left: Typical 2-channel
inspection phase –
Façade Sound
Insulation is measured
with traffic noise as a
source. This is
indicated by the car
‘traffic’ icon
Centre: 2-channel
save phase – overview
Right: Type 2270
connected to two
microphones through
the Dual 10-pole
Adaptor
2-channel measurements (Type 2270 only) are as easy as single-channel measurements.
In Fig. 6 (left), L1 and L2 Position 3 has been measured and saved. You are now ready to measure in the
next 2-channel position. The Overview tab view (Fig. 6, centre) shows all the measured and saved positions,
with any smiley icons and annotations (paper clip icon). Any position may be excluded from the average
calculation by tapping the check mark.
Reverberation Time
Reverberation Time (RT) is an important parameter describing the acoustic quality of a room or space. It is
important for sound levels, speech intelligibility and the perception of music. In building acoustics, it is used
to correct for the effects of RT on building acoustics and sound power measurements.
Reverberation Time is the decay time for sound in a room after the excitation stops. It is the time for a 60 dB
drop in level, but the decay is usually measured over a 20 or 30 dB drop and then extrapolated to the 60 dB
range. It is labelled T20 and T30, respectively, for those two evaluation ranges. The Reverberation Time may
range from 0.1 seconds (or less) in anechoic chambers, to 10 or more seconds in large public spaces.
Fig. 7
Reverberation time
measurement –
measured using the
interrupted noise
method
Reverberation Time varies between
positions in a room, so it is usually
measured at several positions. The average
can be determined for the RT spectra, or
the decays for each frequency band can be
averaged and the Reverberation Time
spectrum then calculated for the averaged
decays (ensemble average).
Reverberation Time can be measured using
either Impulsive Excitation (Schroeder
Method), from a starting pistol or balloon
burst, or by using Interrupted Noise.
All it takes to measure Reverberation Time
is to press the Start/Pause pushbutton (and
burst the balloon in the case of impulsive
excitation). Reverberation times from 0.1 to
up to 20 seconds are then measured at peak sound levels up to 143 dB. No trial measurements, no
overloads, and the ‘traffic light’ clearly shows the measurement status from a distance.
A Reverberation Time spectrum, showing T20 and T30, is included in Fig. 8 (left). A yellow ‘smiley’ icon
indicates that you may be able to improve the measurement at one (or more) frequency bands – if just one
position shows a red smiley, then the ‘master’ smiley will also be red. Tap the relevant smiley icon to read the
explanation. A reverberation decay curve for 1/3-octave band is included in Fig. 8 (centre) and an overview
of results at one frequency band is included in Fig. 8 (right).