The Envelope Please

One often overlooked aspect of audio is the envelope. The characteristics of how the sound is shaped in respect to attack, sustain, release and decay.

We pay close attention to the envelope because it can contribute significantly to how instrument’s interact. Just as tone and frequency can influence how well instruments sound together, envelope is also a major factor in the clarity of a recording.

The best place to begin is by grouping instruments into envelope types. For example, a drum when struck has a fast strong attack, little sustain, quick release and depending on the tuning and type of drum a short or medium decay. Compare that to a flute which has a softer attack, the ability to sustain for a significant time and has a quick release and decay. These two instruments would compliment each other well as far as their ability to be distinguish one from another in a mix. But if you compare a xylophone and an acoustic piano, both have very similar envelope types and may need extra work in both the arrangement and mixing process.

The other reason to consider an instrument’s envelope is how it is effected by compression. Compression is used in one capacity or another in almost every mix. How you use it depends on your objective. It can be used to control levels and calm extreme volume peaks or it can be used to re-shape an instrument’s sound or even an entire mix. The important point is that compression alters the envelope.

A snare drum has a fast strong attack, little sustain and, depending on the type of snare and tuning, a medium to short decay. Oftentimes compression is used to control harshness by limiting the amount of attack or can be used to achieve a “fatter” sound. This involves using compression in a specific way to alter the envelope. There are two methods. One is to set the compressor to kick in fast and squash down the first hit of the snare. This can level out the whole envelop so once you bring the gain back up, the whole envelope is fuller and lasts longer. The second is to set the compressor to kick in after the initial attack letting the snare hit come through unchanged increasing the dynamic range. But then soon after the compressor is set to kick in hard with added gain and essentially lengthen the decay and make it a more robust sound. Depending on the technique you use, this can totally re-shape the sound of a snare from a thin weak sound to a punchy strong snare.

Snare Before Compression

Snare After Compression

Some people tend to add compression to every track as well as the entire mix. However, if compression is not used properly, it can have a devastating effect on a track or mix so should be used with a purpose in mind. Since it alters the attack of an instrument it can have the opposite effect and squash the best part of a sound and basically take all the life out of a track or an entire mix.

When it comes to the arrangement and how your tracks are mixed, you’ll reap great benefits by considering the envelope of each instrument.

QUICK TIPS

1) Take a minute to imagine each instrument’s envelope type. May even be helpful to draw them on a piece of paper!

2) Whenever you add compression ask yourself what the objective is for its use and apply it accordingly.

3) Don’t be afraid to experiment with compression or reverb to get the effect you need. Using presets can be a great starting point but every instrument is unique so consider what you are trying to accomplish.