On 09/06/2014 04:26 PM, Jim Brown wrote:
...
From Psychoacoustics (the science of how the human ear-brain
combination works), we know that we process sound in narrow chunks of
bandwidth called "critical bands." The ear tends to process sounds
within that band together, so when the filter gets too narrow, the
filter skirts fall with the critical band and ringing begins to
obscure the desired signal. The width a critical band varies with the
sound spectrum, and is in the range a 1/3 octave to 1/6 octave. An
octave is a 2:1 ratio of frequency.
That corresponds with my intuition. I long ago figured out that when
using a very narrow-bandwidth filter, I can copy a lot better if I lower
the filter center frequency. For example, with a 50 Hz bandwidth I can
copy better if I tune the filter from the standard 800 Hz down to 300 Hz
or so. That's about 1/5 octave.
Alan N1AL
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