When musicians, whether they're guitarists or drummers, alter the rhythmic feel of a piece of music so that the tempo feels like it has been either cut in half or doubled, but in actuality the pulse and pace of the chords remain the same, it’s called half time and double time.
Half and double time are most apparent when done on a drum kit. Imagine a drummer playing eighth notes on a hi-hat along with the kick on beats one and three, and the snare of beats two and four. That’s common time.
Now, imagine the kick only on beat one, and the snare only on beat three, both still with eighth notes on the hi-hat. That’s half time, and it gives you the illusion that the tempo has been halved, even though the tempo hasn’t changed. (The steady eighth notes on the hi-hat keep the music connected to the underlying pulse.)
In half time, drummers may play around with various hi-hat, kick, and snare patterns, but the overall feel is that of half fast. The Police’s “Don’t Stand So Close to Me” begins with a half-time feel. When the song reaches the chorus at 0:58, you get the impression that the rate of the music has increased, but really the half-time section makes way for regular common time. The half time resumes at the next verse.
“Wrapped around Your Finger” by The Police does something similar. Listen to the chorus at 1:40, which is played in half time, and compare it to the chorus played at 3:34, which is played in regular common time. Other songs by The Police that include half-time sections include “Driven to Tears,” “Every Little Thing She Does Is Magic,” and “Walking on the Moon.”
Claiming to be heavily influence by The Police, Rush made the half-time feel a regular staple in their music, as heard in “Digital Man,” “New World Man,” “Distant Early Warning,” “Manhattan Project,” “War Paint,” and “Ghost of a Chance.”
Double time is just the opposite of half time. It makes the music feel as though the rate has doubled, but again, the underlying pulse remains the same.
Imagine, again, a drummer playing eighth notes on a hi-hat along with the kick on beats one and three, and the snare of beats two and four. Now imagine the kick on beats one, two, three, and four, with the snare in between each beat, producing a 2/4 feel.
This change of feel is best heard in “Should I Stay or Should I Go” by The Clash. Around the 1:08 mark, the music sounds as if the tempo increases, but it really just changes to a double-time feel, and the underlying pulse remains the same. As a guitarist, notice that the chord progression, including the duration of each chord, doesn’t change — only the rate at which you strum. Metallica’s “Whiplash” features regular common time at 2:40, then double time at 2:53, and even a convenient “Here we go!” prompt to cue the change. Metallica’s “Battery” switches back and forth between regular and double time, too.
Some songs feature a double-time feel throughout, like “American Girl” by Tom Petty and the Heartbreakers and “Walking on Sunshine” by Katrina and the Waves.
A common technique used in improvised jazz solos is to switch from eighth-note-based lines to sixteenth notes, but without changing the pace of the chord progressions, giving the listener the impression that the music has sped up. When the accompaniment also follows this double time, the impression is made even stronger.
