Layering sounds is one of the very effective tricks when it comes to musical arrangements. Its origins are pretty old. Probably just as old as musical instruments are. People usually reach for layering when they want to achieve a kind of sound that’s not there to begin with. It can be either an attempt to correct a sound that’s not perfect. Or to get something completely new and different.
Layer for the attack
Layering sounds to bring out the attack transient: Not so long ago, the only bass instrument that was widely available in a recording studio was the old and venerable upright bass. This instrument was originally designed to be played with a bow. In the modern, popular music genres however, the upright was sort of required to be played the pizzicato (plucked) way. Most of the power and volume of the upright bass diminishes this way. Along with the transient attack of the notes. So there’s not much an engineer could capture on tape with a microphone. Of course in some genres like rockabilly, people learned to slap the strings against the fretboard rhythmically to overcome this problem. But this solution was far from perfect. That’s when people invented the tic-tac bass technique. It involves a baritone guitar (traditionally a Danelectro or the Fender VI) or a regular guitar doubling the bass line. Usually played with a pick in a muted way. Layering it on top of the upright’s sound gives a nice attack. Making it easier for the ears to find the bass in the mix. This technique works for an old school, muddy bass guitar sound as well. Just listen to “Hotel California” by the Eagles for example. You’ll hear the clean electric guitar doubling the bass line an octave higher. You can do this to every element that’s lacking a healthy, well audible attack transient. From synth sounds to overcompressed tracks.
Make some changes
Bring out sustain: Sometimes it’s sort of the other way around than what we discussed above. It’s when you have a percussive track that sounds pretty good. But lacking sustain. You don’t want to risk making it sound distant with using reverb? Well, you can still add an instrument under it that’s got a natural sustaining quality. For example, if you recorded a muted bass guitar line played with a pick, you can bring up a piano track under it. Playing the same bass line. Is it your piano track that’s percussive (happens usually in the higher register)? You can always add a synthesizer pad under it to get that larger than life piano sound. Think Bruce Hornsby’s “The Way It Is”, for example. Another trick is to layer a sub bass signal – usually a simple sine wave – under the kick drum. This way, every kick hit will decay into a sustaining sub bass note. It fills out the low end nicely and effectively. This technique is often used in modern hip-hop music.
Change the overall texture of the sound: This is the case when you have pretty much absolute freedom about what you want to do. One common trick for example is to add a so called “whisper track” to vocals. With it, you can really bring out that expensive sounding high end of a vocal sound. Without compromising a powerful midrange that’s already present. For example, imagine recording a rock lead vocal track with an Shure SM7. With its natural treble roll off. You want to add some shine to it? Start boosting the EQ at and over 10kHz. You’ll end up adding a lot of noise as well. It would also suck on a naturally “essy” singer who you deliberately de-essed previously. That’s when you make him/her sing a separate whisper track. Voilá, your high end is there. You can of course do other things as well. Like layering the sound of a distorted electric guitar and an acoustic guitar on top of each other. Or put a percussive bell sound on top of a piano sound. There’s an additional effect of placing sound layers on top of each other. It’s the natural comb filtering that occurs. It’s because of the phase relationship of the two (or more) sounds. So you’re still new to this technique? Just dive in and play around with your tracks. You will surely stumble upon some enjoyable results.