Not too good. In the 20 to 40 Hz range you are looking at a 15% reduction in sound intensity (NOT in decibels, a 10x logarithmic measurement of sound) per 1/4 inch piece. Say you have 100 dB of sound coming in at 30 hz the math works like this: log(10E6) = 10 or 100 in dB (because of the 10x) 10 000 000 * 0.85 => 8 500 000 log(8.5E6) => 9.929 or 99.29 in dB (no perceptive change)

At the higher freq (4000+ Hz) you should see drops of 50 to 70% for a 1/4 inch piece. Using 100 dB again we have: 10 000 000 * 0.40 => 4 000 000 log(4.0E6) => 9.602 or 96.02 in dB for a 1/4 inch piece (much better! A clearly obvious change)

Another thing to remember is that 1/4 + 1/4 != 1/2 Say we use the 30 Hz example it would be: 0.85 * 0.85 => 0.7225 or a 27.75% reduction, NOT an additive reduction of 15%

For reference of how loud things are:

Motorcycle right beside you: 100 dB Subway train about 200' away: 95 dB

See: http://www.gcaudio.com/resources/howtos/loudness.html For a full chart.

Hope this clears up some things :)

Thank you.

I've lived in apartments, but it's never been the treble that bothered me, and I never figured that we'd ever see a bass-proofing that would meet my needs. So... I switched to renting houses. (And eventually buying one.)