Synthesizer: A synthesizer is a machine or software program which is used to create “synthetic” sounds, or “synths”. These sounds can mimic “real” sounds (like a trumpet) or can be completely synthetic, as in a lot of electronic music.
Sampler: A sampler is a machine or software program used to play existing sounds, either in part or whole. The sounds played could be an audio recording, a previously created synth, or any other type of audio. Samplers will usually give you ways to modify the sound in various ways: changing the speed or pitch, reversing the sound, adding effects, etc.
Sequencer: A sequencer is a machine or software program that lets you take existing audio and sequence it together to make music. The general idea is to place one or more sounds at the beginning, then place one more sounds after the first ones (so that they play in order), and continue doing so until the song is complete.
Synthesizers, samplers, and sequencers are the basis of electronic music, and often you will find software that performs all three of these functions, negating the need for multiple programs.
ADSR (Attack, Decay, Sustain, Release) Envelope: The amplitude envelope of a single signal run through a synthesizer. The attack describes the time it takes from the signal start for the note’s amplitude to go from zero to a peak amplitude. The decay is the time it takes for the amplitude to drop from that peak to the sustain level. Sustain, unlike the other parameters, is an amplitude level, not a time. It is a plateau where the amplitude will remain until the end of the signal. When the signal ends, the release is the time it take for the amplitude to drop from its current level to zero.
Breathing: Also known as pumping, this is an effect caused by use of a compressor. As a compressor artificially changes the volume, “ideal” release settings will make the change fairly transparent as it will effectively match the expected release of the source. If the settings are not a match, the signal will sound like it is “breathing”. Originally, this effect was considered undesirable. More recently, this effect has been used in various ways. One, it gives a lot of electronic dance music its signature pumping bass lines. Second, along with “sidechaining” it is used to help automatically keep a bass in sync with a kick drum.
Antecedent Phrase: A phrase that “asks a question” or lends itself to a musical response. The first half of a “question and answer” sequence.
Consequent Phrase: The “answer” to an Antecedent Phrase. Usually a phrase that is a modification or compliment to the Antecedent.
Parallel Period: A musical phrase consisting of an antecedent and a consequent phrase. The consequent is a slight variation on the antecedent, usually with the same musical construction, but differing in cadence. Notated as A | A’
Double Period: A more complex parallel period usually in the form of A | B | A | B’. It is essentially a repeated set of antecedent and consequent phrases, where the second repetition of the consequent phrase differs slightly to close the idea.