16 Other FX

Vocoder

A vocoder uses two sound signals as inputs: a voice (the carrier signal) and a synth sound (the modulator)
In Logic, you set it up using a vocal track input as a sidechain to control the synth; it analyses the frequencies in the voice and modulates the volume of each part of the voice’s frequency range based on the synth sound
This resulting signal sounds like a robot voice that follows the notes / chords you play on via MIDI or keyboard.

A talkbox shapes a signal’s frequency content based on a musician’s mouth position via a tube.

Vibrato modulates the pitch of the signal using an LFO; tremolo modulates the volume of the signal
Modulated delay FX combine wet and dry signals, but vibrato and tremolo consist only of a wet signal
You might see the term ‘rotary’ with vibrato and tremolo; this is an effect used to simulate the Leslie speaker.

Ring modulation adds and subtracts two frequencies to produce two new frequencies; it can be a very dissonant effect that is used to create ‘ringing’, ‘metallic’ or ‘bell-like’ sounds or subtly can sound like phaser or tremolo.

When a pitch shift is pushed beyond ‘reasonable limits’ the part can sound unnatural, ‘metallic’ or ‘grainy’
If a vocal part has been pitch shifted up a lot, it will have a ‘chipmunk’ quality to the voice
When adding harmonies with pitch shift, it is rare for the interval to be exactly the same all the way through; a harmonizer is a more intelligent pitch shift that knows how to decide between e.g. a minor / major 3^rd
Both pitch shift and harmonisers have a little latency when working, which we hear as a small delay.

The word ‘AutoTune’ is a brand name, like Hoover or Jacuzzi; more generally pitch correction / automatic tuning
AutoTune was first used solely as a corrective tool but during the early 2000s, it was increasingly used as a creative effect / feature of the music with a fast or instant (0ms) response time to give an R&B effect
Modern DAWs incorporate functions such as ‘flex-pitch’ and ‘flex-time’ (Logic) and ’VariAudio’ (Cubase)
More premium plugins can now polyphonically retune parts, picking out and changing individual notes in a chord

Wah wah sounds like its name; it is onomatopoeic and is commonly used in funk to make guitar solos interesting
It sweeps the centre frequency of a BPF; if you press your foot forward, the centre frequency sweeps up, making the signal brighter. If you press your heel back, the centre frequency sweeps down and makes the signal duller.

Distortion or degradation of the signal is normally avoided; lo-fi production techniques deliberately degrade the audio signal in some way; this can give a retro / vintage feel or a nostalgic sense of old recording media
Unwanted noise was difficult to avoid in early recordings but has since been as a choice for creative effect
This can give contrast or impact between sections in a track or to contrast with the hi-fi parts of a production
It can be a reaction to modern production which can be seen as sterile or clinical; it is easy to do on a DAW
Producers simulate limitations as part of their creative process / use emulations of old equipment or techniques
Distortion was the first deliberate ways to degrade a signal; giving a gritty sound / adding power and harmonics
Lowering the bit depth / sample rate leads to a bitcrusher effect, emulating the alias tones from early samplers
Samples from early recordings can have noise left in (e.g. hip hop); the same is true in recording (e.g. punk)
Some manufacturers create plugins to deliberately add noise / emulate vinyl (e.g. in hip hop / trip hop)
Saturation / tube / tape emulation plug-ins can be used to add harmonics / thicken the sound
Tape wear / stretching / wow and flutter can be emulated with plugins or using real tape to give warmth
Frequency response can be restricted (e.g. telephone effect on vocal with a band pass filter)
Found sounds are non-musical samples often used as ambient sounds in e.g. trip hop (e.g. rain / waves).