# LabVIEW

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## sound meter

I want create a sound meter. I want that an audio input is indicated by an
I use a sound configuration and sound read, but then how can i link audio

thanks
paolo
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## Re: sound meter

You could fully wave rectify the signal (abs(x)) then low pass filter
with a Butterworth at a low cut-off frequency. Take the output to an analogue
meter.

Paolo wrote:

> I want create a sound meter. I want that an audio input is indicated by an
> I use a sound configuration and sound read, but then how can i link audio
>
> thanks
> paolo
Message 2 of 4
(1,322 Views)
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## Re: sound meter

Hi Paolo,

I would suggest a rectification of the signal. But low-pass filtering isn't
that good, because you would get linear distortion (you would cut off the
high frequent signals, which should also be taken into account in a power
meter.
A better way is to take the data points to power of two (x^2) to get the
function equivalent to
power(t). Then integrate over equidistant intervals (take a running average
over n power data points).
This you can wire to an analog meter.
Have fun,

Oliver Friedrich

"Paolo" schrieb im Newsbeitrag
> I want create a sound meter. I want that an audio input is indicated by an
> I use a sound configuration and sound read, but then how can i
>
> thanks
> paolo
>
>
Message 3 of 4
(1,322 Views)
Highlighted

## Re: sound meter

Yes if its power - I thought you meant just signal level!

Of course you have to square and average.

Oliver Friedrich wrote:

> Hi Paolo,
>
> I would suggest a rectification of the signal. But low-pass filtering isn't
> that good, because you would get linear distortion (you would cut off the
> high frequent signals, which should also be taken into account in a power
> meter.
> A better way is to take the data points to power of two (x^2) to get the
> function equivalent to
> power(t). Then integrate over equidistant intervals (take a running average
> over n power data points).
> This you can wire to an analog meter.
> Have fun,
>
> Oliver Friedrich
>
> "Paolo" schrieb im Newsbeitrag