Ambient sounds can be any background sound designed to hold tension, move with the song, or set a mood. Typically, they are used as fillers and can be added anytime throughout the stages of production as they don’t take up very much headroom being a low amplitude, and most of the time, stereo sound.
Ambience is an extremely effective tool as it requires only a subtle amount to enhance the entirety of a production and can be used in a variety of ways.
Having ambient tracks harmonically follow the direction of the main theme of the song can help thicken the overall sound via layering. Simply duplicating your chord progression and swapping the instrument for an ambient-type sound is the fastest method of creating assisting ambience and will also ensure it follows the notes exactly.
Another method of using harmonic ambience is to hold or generate tension during build-up and break-downs. Generating a static chord or note on an ambient track is surprisingly effective at holding the level of emotion whether used as a transition technique between progressions or an overall mood setter.
Experiment with pitch bending on a sustained chord throughout a buildup for dramatic effect.
Ambience tends to be more of an element you feel, rather than hear, therefore, pushing it back in a mix will put a listener into an acoustic space or setting.
The dry/wet function on a reverb device will be the best method of setting the depth of the ambience while the decay parameters will allow you to control the bleed of the previous note tails.
Selecting the correct instrument is key in this situation as a lot of digital presets are distinct in sound and don’t deliver a natural enough texture to act as ambient tracks, especially when using reverb. A reverb can only do so much with ineffective ambient sounds. Look for keywords such as pads, ambience and evolving when searching through preset categories.
Effective ambient tracks are often so subtle that you won't particularly notice its presence, but you certainly notice it's absence. Muting your ambient track during playback is a great way to test this theory.
Once an instrument has been selected, utilizing time-based effects will be the fastest route to achieve a surrounding stereo sound.
Before jumping into these devices, control the low frequencies at every stage you can to ensure it doesn’t begin to create muddiness. Low frequency and rumble are common by-products of ambience creation with reverb.
For a far more flexible input EQ for removing low end, try adding your favourite EQ before the reverb!
Ambience can also describe other layered sounds such as a tasteful touch of ocean waves in the background of a song. Some artists purposely layer vinyl noise or dust behind their clean, digitally produced sounds because they like the "feel" it gives a track, somewhat reminiscence of older times when records were all people listened to. It delivers a familiarity in the sound.
To conclude, if you're finding your track is empty and you're at a loss for ideas. Ambience could be exactly what you're looking for to fill that space and put your listener into a world!