Can I get a finer gradation roll-off than 6db?
The 6db roll-off attenuation for highpass filters seems too big. I tested 6, 12, 24, 36 and 48 and they all sound the same to me. I’d like maybe 1, 2, 4, 6 and 8?
Is there an alternative that would work for my project? I want to exercise the middle ear muscles by incrementally increasing the dB of frequencies below 120Hz from zero to 100%. Six audio samples of 0, 20, 40, 60, 80 and 100% dB would be good.
I think I figured it out. I got the GSVT GMulti plugin. I set freq1 at 120, freq2 at 8000 (the boundaries of intelligible human speech). Main In Gain 0, low cut off, for Band 1 and 3 simply decreased Level in increments of -1.2, -2.4, -3.6, etc. Ratio 1 to 1 I didn’t bother with compression. Threshold 0 for band 2, -50 for bands 1 and 3.
Hmm…lowest Level of -6dB doesn’t bring down the levels to 0% unfortunately. Instead:
compression
10.1 to 1 (with -6dB Level)
1.8 to 1 (with 0dB Level)
1.2 to 1 (with 0dB Level)
1.1 to 1 (with 0dB Level)
I don’t really understand what you’re trying to do and I don’t know anything about GSVT GMulti.
The Filter Curve EQ or Graphic EQ can make a more mild slope. You could also look for a 3rd-party “tilt filter”, but it might be hard to fine one that works only at low frequencies.
You can also Generate pure tones (sine waves) at any frequency and any dB level. (The dB SPL will be unknown unless you have an SPL meter, but the relative dB levels are valid.)
Dynamic compression is likely to give you “unknown” results.
If you have program material with bass and speakers/headphones that can reproduce bass you should hear a difference with a 120Hz filter, at least between a 6dB slope and everything else. i.e. A 60Hz tone (one octave down) tone would be -6dB, or -12dB with a 12dB/octave slope.
As the slope gets steeper you’re probably not going to hear a difference between -24dB/octave and anything steeper. (With pure tones you should hear a difference as long as the tone remains audible.)
Do you mean zero sound… silence? A linear filter theoretically never gets-down to zero (pure silence = minus infinity dB). But for example, with 16-bits you can’t go below -96dB. Below that you do get a digital value of zero (-infinity dB in the digital domain).
P.S.
In case you don’t know this, the cutoff frequency is defined as the -3dB point. A 120Hz 6dB/octave filter is down 3dB at 120Hz and a 120Hz 48dB/octave filter is also 3dB down at 120Hz. The dramatic differences will be a lower frequencies.
The filter slopes 6, 12, 18, 24 dB/octave are not arbitrary. They are the slopes of 1st, 2nd, 3rd and 4th order Butterworth filters.
Probably the easiest way in Audacity to filter with an arbitrary slope is to use the Filter Curve EQ effect.
You can customize this in classic filters. Use the Chebyshev Type I for the best results.
Problem solved. Filter Curve EQ did it. Thank you.
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