Currently reading The Audio Expert and my first question is about sub bass and how it relates to the inverse square law.
I'm trying to understand how to create depth in a mix and, up until now, I gathered that distant sounds are band limited toward the midrange. According to the book, 125Hz is the least attenuated of the listed frequencies. However, that's the lowest frequency in the list. What about lower frequencies?
I know that below a certain cutoff, sub sounds are more omnidirectional rather than the arc-like shape of those above. So, maybe the inverse square law is different for them? I tried listening to cars and indeed distant once seem to sound less bassy than when they get close.
So, if I'm mixing, shouldn't background instruments have no sub?
Do you mean by "background instruments" like really ambient ones? If so, I think they should not have a lot of low freq content. Just because they eat so much headroom, and that information is pretty useless.
Interesting question. I can only make a SWAG, but in theory the ISL should apply equally to all frequencies. The fact that higher frequencies tend to "beam" and lower freqs are more omni does not change the ISL's operation, but I think that we need to specify this is only for an anechoic space.
In an enclosed space, we know about room modes and reflections. I imagine that will affect the ISL's equal effect on all frequencies. my 2 cents.
When I was listening to some Dr. Dre, I noticed that whichever bass instrument had the most high-frequency detail, also existed in the sub; the kick, for instance. 'As above, so below' and the other low instrument, like a bass guitar, would be in the middle somewhere. That got me thinking that whatever has prominence, at least concerning the low-end, has sub bass.
I'm ITB and use plugins. A particular brand of plugins, in their help menu, talks about how to create depth and distance in a mix. They say that stereo sounds appear closer even though we think of vocals being panned center. This makes sense when you think about a distant sound.
But my question is: does sub bass make something sound closer or further? We definitely know that we can use a low pass filter to 'push something back' in the mix. We also know that sub frequencies have different acoustic behavior than those above. The higher, the more directional but the more the frequency is prone to attenuation from the atmosphere. Sub bass is basically omnidirectional whereas I can't think of light - despite it being subject to the same law - sharing those same properties; at least not to any appreciable degree. Red doesn't fall off faster than green, for example - not that I'm aware.