APPENDIX
Rule of 400,000: this rule is a general guideline for
presenting a spectrum the listener perceives as
balanced. The upper and lower bandwidth limits are
multiplied, and that number should approximate
400,000. A full range 20-20,000 Hz sound would thus
qualify.
Charles Nairn has suggest a that product range of
400,000 to 640,000 is acceptable.
If, for example, the bass were limited to 150 Hz, having
a treble response to 20 kHz would sound too bright. Inthe first instance, 150-20,000 Hz yields a product of
3,000,000, which is greater than 640,000, and therefore
too bright. In the second instance, the 20-3,000 Hz
yields a product of 60,000, which is lower than 400,000,
and therefore too dull.
Even though having a 20Hz lower limit is desirable,
having a full 20 Hz bass response with a 3 kHz upper
bandwidth limit would sound too bassy.
This rule is not universally accepted, but the author?s
personal experience supports the general preference for
bass-treble balance. I would further suggest that 35 Hz
to 15 kHz should be considered close enough to the
spectral hearing limits that further extension of either
bass or treble would not likely alter the perception of
spectral balance. The author looks forward to knowing
the reader?s thoughts on this subject.
SAE
