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CHAPTER 14

Reverberation Time Software (Optional Module)

153

impulse response by post-processing software like DIRAC Room Acoustics Software

Type 7841.

The recordings will contain the signal from when you press the Start pushbutton until the

measurement stops. The recording will be attached to the measurement as an annotation.

Note: Signal Recording requires a license for Signal Recording Option BZ-7226.

To exit the Setup screen, tap the icon.

14.2.4 Controlling the Measurement

The measurement is controlled in the same way you would control a normal Sound Level

Meter measurement, using Start/Pause, Continue, Reset and Save pushbuttons, see Chapter 3

for more details.

Note the following exceptions:

• Pressing Start initiates a measurement cycle slightly more complex than a standard SLM

measurement – see Fig.14.3 and Fig.14.4 for details. The results are the same, however, a

set of measurement data – in this case the reverberation decays at one position

• Creating a new reverberation time project: The measured data is stored at a position – and

you can have several positions in one project. Therefore, starting a complete new project

cannot be done by pressing Reset and then Start (as when measuring using the SLM

template), because this will measure the decays at a single position within the Project – a

new project is initiated by selecting a new project template (or the same again). This will

create a new project

14.2.5 Serial Measurements

If you have made a measurement using the Interrupted Noise method and at some frequencies you

have not been able to get a sufficient signal to noise ratio. This problem may show up at frequencies

where the background noise has been too high. The frequencies will then be marked with red smileys

(see Table 14.1).

To solve this, you either have to lower the background noise (which might not be possible) or increase

the power of the loudspeaker in the source room.

If your loudspeaker already produces as much noise as possible, you can limit the frequency range of

the noise to cover just a single frequency band while keeping the output power constant, thus

increasing the noise level in the smaller frequency range. For a 1/3-octave band, this will increase the

noise level at the band by up to 10 dB.

To select the frequency bands to be measured (using noise limited to cover these bands only):

1) Select Measurement Control from the Setup screen.

2) Set the Measurement Mode to Serial.

3) On the Spectrum display, select the bands you want to measure using the cursor and tap on

the x-axis to select the band for serial measurement (Fig.14.5).

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