I’ve used the term “frequency dynamics” in music when recording and mixing forever (yeah, I’m about THAT old). However, for some reason recently I decided to Google frequency dynamics to see what I could find from other people and was a bit surprised by the results… mainly because I have no idea what most of those results are talking about. I’m sure all those are interesting, but I really don’t care about hi-frequency dynamics of ocean PH… honestly I don’t even know what that means – I’ll read up on that one later. Either way, it seems I’ve been using a term that maybe isn’t used for recording audio, but I think it should be, so thusly I post.
Frequency dynamics in music, for me, revolves and bounces around overtones and undertones of the complex waves that are created by instruments, voices, animals, tin cans, anything you have in the studio.
All those parts and pieces of a complex sound wave that make it unique, give the sound character, tone, and depth. If those things didn’t exist, every voice would basically sound the same. Our voice sound bank would be about the size of Casio keyboards in the 80’s. As an audio engineer, a big part of the job is capturing those nuances on tape. Every time you lose those “embedded” frequencies within the sound wave what we hear becomes less and less “real”. Less depth, less character… thinner… stale… more electronic sounding. Process a recording of a concert grand piano in a giant hall enough, and it starts to sound like a MIDI piano… b/c most samples lack all the nuances of a real string vibrating and all that does to the vibrations of the soundboard, and everything else surrounding the instrument.
So when you visualize the wave of recorded sound, don’t “see” just what a zoomed-out version of that waveform will show you – think about all of the minuscule variations that are happening within the dominant wave(s) that actually bring that sound to life and make it what it is. You don’t want to lose those things when recording music; especially acoustic instruments and voices where the amplitude dynamics are also large – large as is there is a big “gap” between the highest amplitude and lowest amplitude. For frequency dynamics (as far as I use the term, anyway) it takes amplitude dynamics and includes it with all the frequencies to create a more three-dimensional graph: each frequency in relation fo the next combined with their dynamic (amplitude) ranges.
I’ve seen this a little in relation to Dynamic EQs insofar as “intelligent” digital EQs for theatre systems that analyze frequency balance and boost those “hidden” aspects that give the overall sound more character. (that’s the image above). That’s the home theatre solution to low-level listening to compensate for not being able to hear the nuances of all the frequency “happenings” in a recording…. at least I think that’s what it’s doing ;)
Why does this matter? I’m sure you understand the importance of the presences and capturing of all these other frequencies and how they can give recording more life, presence, and depth… but how to capture that? Because it’s not as straight forward as simply having a set of freq. response charts for your gear that cover the audible frequency range.
Digital audio converters, bit depth and sample rate all play a key roll as well. Look at this digital audio recording post for more on those topics. Having a good grasp of the effects of bit depth and sample rate in relation to frequency dynamics in recorded audio is very important. That tells you WHY a higher resolution and / or sample rate are better able to capture the full character of a sound source you’re recording. Some recordings don’t need it, but if you want to record a track that people will listen to and say out loud, “wow… that sounds really good…” then you have to take those things into consideration. (And when I say “sounds really good” I mean clarity, warmth, depth and presence, not just if you play it loud then the bass kicks and your car shakes.)
Frequency dynamics in recording and music is, in my use of the phrase, all about quality of your sound. It has nothing to do with loudness, it has to do with how “real” the recording sounds, and that’s done by being able to capture while recording, and maintain while mixing and mastering those seemingly infinite number of tiny variations in a sound wave that make it what it is.
The dynamic range of the human ear is approximately 120db (obviously that fluctuates from peson to peson). That’s pretty darn good. And that’s not just a sine wave, it applies, in lesser levels depending on the difference in frequencies, to our ability to hear differences in frequency and tones at the same time – where all those subtle over and undertones are happening. One argument against loudness in relation to our ability to hear all the nuances in sound has to do with temporal masking. Basically if your ears get hit with one frequency at a certain level, usually loud, then temporarily that can mask other frequencies so that you don’t hear them. Too loud harms your ability to hear the nuances of sound. Squashing your sound can also cause similar results, but in that case within the recording, so there’s no chance of ever hearing what was originally “there” in the instrument. In my opinion, you have to protect that stuff when you’re recording and mixing. Yes… admittedly most people won’t hear the difference and don’t care, but it’s always nice to cater to the audiophiles every now and again.
