Third octave band and CADNA-A

[Shellby]

Hi :+) . Has anyone got an advice. I am doing a project to assess
impact of
proposed entertainment noise upon residents. Will be monitoring third
octaves bands on site and want to then build a CADNA-A model of post
development with entertainment noise, car park movements, beeping
horns in etc. However the modelled output at the receiver (monitoring
point) is not third
octave? Therefore , I won't be able to compare to the monitored third
band octave results.

Anyone have any suggestions????

[Mark B]

The third octave bands can be converted to octave bands by
logaritmically adding the three bands centered on the octave band
frequencies. Or you could split the octave band output to third by
doing the reverse.

Why don't you just set the meter on octave bands instead of third
octave bands.

[gu_tar]

Just to note that you can only go from Third to single octave and get
meaniful results. If you split the single octave to third then this
will not represent valid third octave numbers.

Lp 1/1 (for 1000Hz) = 10xLog(10^(Lp 800Hz) + 10^(Lp 1000Hz)+ 10^(Lp
1250Hz) ) Other frequencies follow this.

Although you could log average backward to thirds the results would
not be valid. Also the above equation makes assumptions that the three
third octaves add together constructively and this may not be totally
true so even the above equation does not give rigidly valid results.

The best way to get octave values is as Mark wrote, just set the meter
to measure in single octaves, if the meter can measure in thirds it is
most likely that it can be set to measure in single octaves.

Regards

Tom

[Shellby]

Thanks for the advie much appreciated :=)

[Shellby]

> Tom- Hide quoted text -
>
> - Show quoted text -

Thanks for your help :+)