Appendix C Glossary; Glossary Of Terms; C.1 Overview - Larson Davis SoundAdvisor 831C Reference Manual

Appendix

C.1 Overview

This appendix contains technical definitions of key acoustical and vibration terms commonly used with
Larson Davis instruments. The reader is referred to American National Standards Institute document
S1.1-1994 (R2004) for additional definitions. Specific use of the terms defined are in the main body of the
text.
C.2 Glossary of Terms
Allowed Exposure
Time (T )
i
Average Sound
Level (L )
avg
SoundAdvisor Model 831C
C Glossary
The allowed time of exposure to sound that a constant A-weighted sound level in
a chosen Criterion Level, Criterion Duration, and Exchange Rate.
The equation for T is
i
T i
where L is the Criterion Level, Tc is the Criterion Duration, Q is the Exchange
c
Rate, q is the Exchange Rate Factor and L
Example: If L = 90, T = 8, Q = 3 and L
c c
8
-------------------------------- -
T i =

95 90 –
2
This means that if a person is in this area for 2 hours and 31 minutes he will have
accumulated a Noise Dose of 100%.
Standard: ANSI S12.19.
See "Exchange Rate (Q), Exchange Rate Factor (q), Exposure Factor (k)" on
page C-6.
The logarithmic average of the sound during a Measurement Duration (specific
time period), using the chosen Exchange Rate Factor. Exposure to this sound level
over the period would result in the same noise dose and the actual (unsteady)
sound levels. If the Measurement Duration is the same as the Criterion Duration,
then L =LTWA(L ) where the Measurement Duration (specified time period) is
avg C
T=T -T and q is the Exchange Rate Factor. Only sound levels above the Threshold
2 1
Level are included in the integral. Standard: ANSI S12.19
T c
---------------------------------------- - ------------------------------------------ -
= =
  Q  
L avg L c –
2 10
is the Average Sound Level.
avg
= 95 then
avg
8
-------------------------------------- -
= = 2.52 = 2 hours and 31 minutes
 3    10 
95 90 –
10
T c
 q 
L avg L c –
C-1