EnginEARing, Part 5 – Learning The Frequency Spectrum
By Glen Stephan on February 17 2011 06:00 PM | Permalink | Author Info
In Part 4, we got away from the studio, getting our ears used to listening in detail to the sounds of the world around us. Now we can take those basic critical listening skills back home to begin to learn the crafts of critical and analytical listening in the studio.
First up: Name that frequency...
WHAT”S THE FREQUENCY, CLYDE? (KENNETH”S NOT HERE)
A very common type of question asked by those just getting into music engineering has to do with “rules of thumb” for equalizing, as in, “How should I EQ my guitars?” or, “”How do you EQ your kick drums?” and so on. As usual, there is plenty of “conventional wisdom”, as well as charts and graphs out there telling us to do things like “cut everything below frequency x for everything except bass and kick drum” or “cut 400 Hz on this and boost 4kHz on that in order to get a nice punch on the other thing”. And as usual, the “conventional wisdom” turns out to be OK half of the time and completely unfit for the other half, and mostly just winds up getting in our way when it comes to learning how to truly master our craft.
If we want to get it right 100% of the time and always be able to figure out just what, if any, EQ is needed for any particular situation, we need to learn to use our ears and our heads to figure it out, not depend upon some stale rules of thumb which are wrong half of the time. Unless one has a legitimate tin ear or tone deafness – in which case, they’re almost certainly pursuing the wrong avocation in recording and engineering music – it’s really not all that hard to train our ears to do that. Once we have learned the basics of avoiding the common listening biases (parts 2 and 3) and the basic art of listening to the detail of the sounds around us (part 4), we are ready to start learning just what the various frequencies actually sound like. With that knowledge, questions such as, “How should I EQ my guitar?” and the rest will start dropping like flies, as our ears will provide us with the answers almost intuitively.
There is one basic exercise we can perform that will, in just a couple of weeks, have us knowing the difference between 200Hz, 400Hz, 2kHz and 4kHz with one ear tied behind our backs. All it requires is some music recordings, an EQ, and a little practice.
THE EQUALIZER: COME WITH ME IF YOU WANT TO HEAR
Equalizers are commonly used to shape the sounds of our various tracks by boosting and cutting the volumes of the various frequencies generated by that track in various ways. In this case we’ll use them instead to shape our ears and hone our knowledge of the various frequencies, what they sound like and how they each may be helpful or detrimental to just what we are hearing. The technique is ridiculously simple, and will show results in an increase in the quality and precision of our hearing in just a matter of days.
While almost any type of EQ can be used for this exercise, I find the good old-fashioned graphic equalizer to be the best tool to use. It’s intrinsic “graphical” design of laying out the frequency bands side-by-side in ascending order from the lowest frequencies (~20-25Hz) to the highest frequencies (~16kHz-20kHz).with each frequency control, or band, labeled by it’s center frequency, makes the learning and visualization of the frequencies just that much easier for most folks.
The number of bands the EQ has is also important. The spectrum should be broken down into enough bands to make leaning them worthwhile. But I also find that one with too many bands tends to get too confusing too early because the difference between two adjacent bans may not be so readily audible to those of us just learning this stuff. I find that a 2/3rds octave graphic EQ - i.e. one that breaks the spectrum up into 15 bands of EQ control - seems to hit a nice “sweet spot” of band resolution for getting to learn what the various frequencies sound like, though anything close to that, from 12-band 16-band will work pretty well also.
I also prefer analog hardware EQs for this process, simply because they tend to work faster (with no latency) and sound better than most of their plug-in counterparts. But I also understand that not everybody has access to a 2/3rds octave hardware EQ, so a plug-in can suffice. If you have a choice between the two, however, choose to use the hardware one for this purpose.
I GOT THE MUSIC WITH ME
he next thing we’ll need for our exercise is some music to listen to. Here it’s best to pick two or three commercially released CDs. The first CD should be one of our favorite CDs of one of our favorite artists, one that we think has a high quality sound to it and that we are also fairly familiar with already.
The second CD should be one that you are not necessarily so familiar with, but is a well-produced album that (hopefully) incorporates more instruments than just guitar, bass and drums in a clean arrangement that allows each instrument to be heard as an instrument either in full accompaniment or in solo.
The third CD should be something of a more classical/orchestral nature, again one known for its recording quality and production value that will really provide our playback system and our ears with the full quality of frequency response to be able to listen to and work with during our exercises.
I’M WITH THE BAND
Now setup your graphic equalizer with all the frequency bands turned or slid all the way down to maximum negative gain. Take the first CD from the music you have collected for this exercise, and play it one song at a time through that equalizer (with no other effects in line).
As you play each song, take one frequency band slider (starting with the first one on the left), and slowly start to raise it or turn it up. Listen closely to the music as you raise the gain on that single frequency band, paying close attention to just how the character of the sound changes, Listen to each instrument or voice in turn, listening to just what that instrument sounds like when you raise that frequency band.
Make sure now to take note of the frequency value for that band, so that you can relate those sounds to that frequency value.
Next, pull the gain for that frequency back down and repeat the process again for the next frequency band. Note the frequency value on that band, making the mental note that that’s what that frequency sounds like on each of those instruments and the song in general. And then pull that one down and raise the next one. And so forth down the line until you run out of frequencies to test. Then go back to the first slider on the left again, and start all over again, as your CD keeps playing new music.
Change up the CDs every once in a while to change up on the music styles. This change serves a couple of important purposes.
First, it helps prevent our ears from listening to the same stuff over and over. This helps avoid mental boredom on our brain’s part; we’re more likely to stick to it if the music stays fresh. It also helps us avoid ear “fatigue”, where our ear’s sensitivity to detail seems to slack off after excess repetition of the same sounds.
And second, but equally important, is that the variety of music and recording styles allows us to hear a greater cross-section sample of just how the various frequencies sound. It helps the ear to train by exposing it to a variety of not only music styles, but engineering and production styles, and hearing how the various frequency bands sound on each of them.
As we perform this exercise for a good half-hour to an hour a day, and get better at hearing what each band sounds like, we can start changing up the order in which we select the frequency bands to boost. In a very short time – within a week or two – we should be able to bring in a friend or family member to help us. Have them take over the task of randomly boosting the frequency bands one at a time, but this time without letting us see which ones they are moving. Then we have to call out the frequency value we believe them to be raising based solely on what we hear.
Try it first with the music with which we’ve been practicing, and then have them introduce some fresh recording with which we have not practiced.
It should not take very long for us to discover that we can with some regularity pick the right frequency within one or two bands most of the time. We may not score exactly 100%, and that’s OK, if we can at least ballpark it within a reasonable margin of error each time, we will have come a long way to having out ear trained to recognize the various frequency ranges by ear, which will be a major step in our ability to engineer in the studio.
Not bad for only spending an hour a night for two weeks or so listening to music.
Next up: Part 6: The Frequency Chart Part I - Meanings Within The Frequency Spectrum