Larson Davis System 824, Руководство по обучению

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3/22/01 RT60 Measurements 3-7
Step 7
Press the VIEW
key, highlight “Autostore” and
press the right arrow key. Select RT60 and press
the Check
key.
To easily access the RT60 menu to
change the “RT60 dB Down”
parameter, press the Check
c key
from the RT60 display.
With the “Auto-Select” feature selected, a vertical line or
cursor will be positioned on the time sample that is 5 dB
below the maximum level. A horizontal line will be drawn at
the level that is the number of dB down from the cursor
level. The RT60 will be calculated using the least squares
method on the data between these two points.
To view each frequency, use the up
and down arrow
keys.
Hint:
Due to the differing geometries and acoustic characteristics of some
rooms, a perfectly linear decay curve may not always be obtained.
Using the left
land right rarrow keys a custom start point can be
chosen and the “RT60 dB Down” setting can be adjusted, as desired, to
bound the area of slope calculation.
Advanced RT60 Measurements
Since every room or situation may be different, it may be
necessary to make some adjustments to the standard settings
provided in “RT60-A” and “RT60-B”.
A more accurate appraisal of the reverberation time of the
room can be made by averaging together several measure-
ments possibly at varying locations.
Triggering A good understanding of the triggering menu and its capa-
bilities will help you better make setting choices for your
particular application. The diagram on the following page
discusses these five states: