How to test octave filters?

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timhsiao582@gmail.com - 24 Apr 2008 22:30 GMT

Hi, all

I am new to the acoustics field. Recently, I am working on a project
related to the octave filters. My colleague has implemented the
digital octave filters on the instrument with output and input
channels.

1. How to verify the shape of the octave filters conformed to the
standard ANSI S1.11?

I've read the standard ANSI S1.11 but still don't understand "level
difference" and "reference level difference" explained in the
standard.

2, What are the definitions of "level difference" and "reference level
difference"?

3. How to calculate or measure the "level difference" and "reference
level difference"?

Thanks for your kindly help.

Tim

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Fred Marshall - 03 May 2008 23:03 GMT

> Hi, all
>
[quoted text clipped - 19 lines]
>
> Tim

1) pick a reference frequency

2) measure the input to output level change at the reference frequency -
that means a sinusoid.

3) measure at other frequencies with the same input amplitude and measure
the output amplitude. Refer the result to the reference.

So, the "level difference" would be from input to output at a particular
frequency and the "reference level difference" would be from one frequency
to the reference frequency.

At least that's my guess from whatever source you're quoting.

Fred

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Natural Science Forum / Physics / Acoustics / May 2008

How to test octave filters?