3M DL, SE user manual Reverberation options, Reverberation time set-up options

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Additional options

Reverberation options

Reverberation options

The following setup options are selectable via the Reverberation Time Options Setup menu (displayed in Figure 6-3).

Field Description	Explanation of field selections
Method -	Interrupted – (This is the default method setting.)
Selecting the	Interrupted method uses a constant sound source (i.e., dodecahedral
calculation process	speaker), waiting for the level to stabilize, and then the source is turned
of RT60 reverb	off. (The method uses random noise or pink noise to test reverb. time.)
time.	Impulse – Impulse method is when the user tests the room with a
	broad spectrum impulsive noise, such as a starter pistol or a balloon
	popping.
Averaging –	Measurement – The RT60 result times for each filter band of the 1/1
Selecting how it will	Octave or 1/3 Octave modes are averaged across the studies to arrive at
calculate Average	a session average RT60 for that frequency band.
for Reverb-time	Ensemble - The decay curves for each filter band of the 1/1 Octave or
	1/3 Octave modes are averaged across the studies to arrive at an
	average session decay curve for that frequency band that is then used to
	calculate the session RT60 for that band. This results in either eight or
	twenty-four session ensembles, one for each frequency band in 1/1
	Octave or 1/3 Octave modes, respectively.
Threshold -	Auto - (This is the default threshold setting.) The instrument will
Specifies the dB	automatically chose the level and calculate RT60. When in run mode, it
level for triggering	sets the threshold relative to the noise level in the room. It provides a
the start or run of	trigger level which is customized to each band.
the instrument. The	40 dB – 140 dB (in 1dB increments). The threshold decibel is user-
interpretation of this
field is dependent	selectable between 40 dB to 140 dB in one decibel increments.
on the	• For Interrupted Noise method, level below this threshold will trigger
measurement	the start of a measurement.
method.	• For Impulse method, levels above this threshold will trigger the start
	of a measurement.
Measure -	Auto - (This is the default Measure setting.) The instrument will
The expected	automatically pick the best Txx value based on the expected decay (i.e.,
decay value	T20).
	T60 (T10 – T60) – (The default setting is Auto.) The selected “Txx”
	value is the actual amount of drop/decay the instrument measured. The
	selectable ranges are T10-T60.
Filters -	Measurements are plotted and stored in 1/1 or 1/3 octave band chart
1/1 or 1/3 bands	and decay chart. This field is only selectable if both 1/1 and 1/3 octave
	filter bands are installed features. Otherwise, the instrument will apply
	the installed filter.

Table 6-1: Reverberation time set-up options

Models SE and DL