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Just checking in the 'collective knowledge' here. As far as we know, there's no advantage to higher sampling rates when using the CNF is there? I know it helps with impulse noise, but I wondered about the CNF.
When one uses a higher sample rate with the CNF, the frequency bin width is raised. So, for example, if you are using 1024 ffts at 44.1 kHz, the bin width will be ~ 86 hz. That same fft size at 96 kHz will become ~188 Hz. So, put another way, the selectivity of the CNF is reduced with higher sample rates at a given fft size. In audible terms, it may have a harder time discriminating adjacent noise frequencies from one another, but will have an improved time domain transient response. So, I guess one should consider raising the fft size for 96 kHz sampled files to get similar results compared to 44.1 kHz sampled files.
I do not know if that answer is clear - - - probably not. Let me know if not and I will try to clarify it some more.
That's clear, Craig and Marc. So I guess if you are working with a 96kHz file and you're not ready to convert to 16 bits yet, you could raise the fftsize to compensate. Is there a basic formula for estimating how the sample rate and fft size change the bin size?
When one uses a higher sample rate with the CNF, the frequency bin width is raised. So, for example, if you are using 1024 ffts at 44.1 kHz, the bin width will be ~ 86 hz. That same fft size at 96 kHz will become ~188 Hz. So, put another way, the selectivity of the CNF is reduced with higher sample rates at a given fft size.
So it implies another question-isn't better to make downsampling to 22 kHz?
No - downsampling to 22.05 kHz will cut the top end off and you will only have a frequency response to ~ 11 kHz. Not a good idea. To imrove selectivity, consider raising the FFT Size.
Craig
"Who put orange juice in my orange juice?" - - - William Claude Dukenfield
I have found that it largely depends on the nature of the music as to what value ultimately works the best. But, I too start off with 2048 and then experiment up or down from there.
Craig
"Who put orange juice in my orange juice?" - - - William Claude Dukenfield
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