At 11:57 PM -0700 3/29/08, Louis Judson wrote:
>Interesting sounds, Paul! I gather the EQ is on the second half - I
>have only laptop speakers at the moment... It's actually a cut if so.
>
>2 thoughts: I think you mean "F-M" for Fletcher-Munsen, rather than
>Frequency Modulation's "FM" (we are engineeres here, if it is a
>quibble).
>
>and, how this would be an inverse of the "loudness" curve on old
>hifi amps, which is +10 @ 100Hz 6dB/Octave and +4 @ 10k 3 or 6 dB /
>Oct. (arbirary as the figures might be, relating the what volume
>level, etc.) perhaps?
Yes, a playback level must be established and retained, then EQ
applied. Still, I can't tell you what volume to use.
>
>Third thing - I think we are aware of more bass in recordings
>because we are amplifying it over the natural level...
Yes, but aren't the other frequencies being amplified at above
natural levels as well? Aren't the higher frequencies more
efficiently heard by the ears upon full spectrum playback? I'm not
contesting that the F-M effect is an influence; I can't figure out
how to explain all of the oddities with just amplification and F-M.
My guess is the whole spectrum (excepting for the F-M effect upon
playback) is fairly accurately captured (with "good" gear). There is
simply a lot of low Hz energy in settings because these frequencies
sounds travel from afar. When we crank the gain of these recordings,
we hear a variety of "flaws" possibly from many sources including the
limitations of speakers. The easiest flaws to address with tools we
have are those associated with perceived tonal balance. Dynamics is
next, but we can't do much about distortion.
Here's a comparison QuickTime movie I made in which I used no
roll-off EQ but rather many bands of parametric EQ attenuating the
frequencies that were exaggerated to my ear. Note that there is quite
a bit of discrepancy between the channels which I also tried to
compensate for. I also felt the mics are a bit dark above 5KHz so I
tried to boost the high end a tiny bit too.
12mb (16/48K uncompressed soundtrack)
http://www.uwm.edu/~type/audio-reports/posting-techniques/media/PaulJacobso=
n_KookaCompareEQH263Lrg.mov
4mb (IMA4 compressed soundtrack)
http://www.uwm.edu/~type/audio-reports/posting-techniques/media/PaulJacobso=
n_KookaCompareEQH263IMA4.mov
Rob D.
>
>2c,
>Lou
>
>On Saturday, March 29, 2008, at 02:41PM, "Paul Jacobson"
><<pj%40cutlerco.com.au>> wrote:
>>Hi All,
>>
>>In a reply to an earlier email Dan Dugan mentioned the Feltcher-
>>Munson loudness curve as an explanation as to why we are aware of
>>more low frequency energy in recordings than which is apparent to the
>>"naked" ear.
>>
>>I made some quick experiments at constructing an inverse differential
>>FM curve last night based on a chart of FM curves. I've tried to base
>>the EQ on the change of emphasis that results from a 60dB boost in
>>volume. The results appear to be quite promising and seem to sound
>>closer to how I perceived the environment when listening at normal
>>levels. There is a significant amount of LF cut, however this is a
>>gradual roll off to approximately -23db at 20hz rather than a steep
>>filter applied at 100hz as I've used in the past. The amount of eq
>>required still needs some work, but I thought I'd share the results
>>of my first experiments anyway...
>>
>><http://www.mactrix.com.au/files/recordings/EQTest.mp3>http://www.mactrix=
.com.au/files/recordings/EQTest.mp3
>>
>
>
--
|