Here’s a classic example of groove: the drum break that opens, shown in Ableton Live’s loop editor.
There’s a close analogy between groove and blue notes. Just like groove is a way of stretching and bending strict metronomic time, so are blue notes a way of stretching and bending the piano-key pitches. Primus Luta extends the analogy to sample-based hip-hop; he defines the “blue notes of sampling” as unexpected sonic artifacts that enhance rather than mar a track.
Groove is a practical term of art in electronic music production. Let’s say you wanted to play or program your own sounds on top of the “Impeach” break. If you were to line them up with the metronomic grid, they would sound off, because they wouldn’t match the timing of the drum pattern. Ableton Live, like many other music production tools, enables you to extract a groove from an audio recording, and use that as the basis for quantizing other events. Using extracted grooves is a terrific way to get your programmed MIDI synths and drum machines to have a funkier feel to them.
Any instrument can define a groove, so long as its note onsets are distinct. For that reason, drums, electric bass and guitar work better than flute or violin. Guitar and bass grooves are interesting because the note endings are just as important rhythmic signifiers as their onsets. A good guitarist or bassist can strum or pluck with good time; an excellent one mutes those notes or chords in time as well.
You might be wondering what the difference is between a groove and plain old inaccurate timekeeping. The big factor is intentionality. Good drummers (which the guy on “Impeach the President” most certainly is) can very deliberately place their hits ahead of or behind the beat. Playing behind the beat intentionally sounds really good. Dragging unintentionally sounds really bad. Ditto with playing in front of the beat versus rushing. It’s a subtle distinction, but it makes all the expressive difference in the world.
You might resist the idea of reducing the mystical concept of groove down to something so technical. You might object that groove is in the heart.
I agree! Groove is in the heart. For me, the fact that music is made of math doesn’t reduce its emotional impact at all. Quite the contrary. I find it totally amazing that the organization of sounds into patterns in time, along with slight deviations from those patterns, can bring a roomful of dancing people into a state of sweat-drenched ecstasy.