MCU17/0005 - IDAS Application - 113 Marara St Cooroy

   APPENDIX A - GLOSSARY OF ACOUSTIC TERMS
   The following is a brief description of the technical tcrms used to describe traffic noise to assist in understanding the
   technical issues presented in this document.


   Evetlt maximum sound pressure level (LA%lldj,T),          un
   The 1.0I level is calculated as the noise level equalled and exceeded ror I % or the measurement time, for example 9
   seconds in any 15 minute interval. 1...01is an appropriate level [0 characterise single events. such as from impulsive or
   distinctive pass-by noisc. In this Report, the measured LOI levels for day/evening/night          arc not averaged but are
   ammgcd from low to high in the relevant day/evening/night interval and the va.lue that is found at the 90th percentile
   (LID of 1.01 sample) in the interval is recorded as its "1.01" level. The level can be adjusted for tonality or
   impulsiveness.


   Average maximum sound pressure level (IA %Ildj, T), L10
   The "LIO" level is an indicator of "steady-state"         noise or intrusive noise conditions from traffic, music and other
   relatively non-impulsive noise sources. The LIO level is calculated as the noise level equalled and exceeded for 10% the
   measurement      time, for example 90 seconds in any 15 minute interval. The measured LIO time-intervals                for
   day/c~eninglnight    3rc arithmetically    averaged to present the "avcmge      maximum" Icvels of the cnvironment      for
   day/evening/night. The level can be adjusted for tonality or impulsiveness.


   BackgroulJd sOImd pressure level (IA90,1), L90
   Commonly called the "L90" or "background" level and is an indicator of the quietest times of day, evening or night. The
   L90 level is calculated as the noise level equalled and exceeded for 90% the measurement time. The measured L90
   time-intervals   arc arithmelically    averaged to present the "average       background"   levels of the environment   for
   day/evening/night. The Ic\'el is recorded in thc absence of any noise under investigation. The level is not adjusted for
   tonality or impulsiveness.


   Equivalent Continuous or time average sound pressure level (l.Aeq,1), l..eq
   Commonly called the "Leq" level it is the logarithmic avcrage noise level from all sources far and ncar. The maximum
   I-hour levels within the day/evening/night lime intervals arc referenced for huilding design. The level can be adjusted
   for tonality.


   Fafade-adjusted level
   A sound level that is measured at a distance of 1.0 metre from a wall or facade. The level is nominally 2.5 dB higher
   than the rree-field level.


   Free.field level
   A sound level that is measured at a distance of more than 3.5 mclres from a wall or facadc.


   Weighted SoulJd ReductUJII/lJdex, Rw
   A singlc number value used to compare the sound reduction index of building clements. Similar to the Sound
   Transmission Class (STC) rating that is still in common use. Rw and src arc not idenlical though may be considered,
   for most applicalions, as being interchangeable. A high Rw indicates high sound reduction.




~ Alpha Acoustics l'y Ltd                                                                         I'age 17 of 17
Doc: J 1562 - Noise Assessment - Paintball Field - Cooroy (Rev 2).doc