# Making "acceleration" effect

my question is how to make song to feel like it is getting faster, without changing tempo? Example of what I actualy mean is:

(watch from 1:45) I know we can change from 4th notes to 8th notes but that's not what I'm looking for, I would like to know how to make rythmicaly correct, step by step fastening.

• I know how to change the tempo within a song with automation in Ableton live but I am not sure that what you asked is possible to do without adjusting the tempo. Nov 20 '12 at 22:55
• What happens in this video is that the beat is getting faster - the tempo ramps up - so your example doesn't meet your requirements. Nov 21 '12 at 10:05
• @esmitex Is that what Aphex Twin used for Bucephalus Bouncing Ball? Nov 22 '12 at 5:30

The musical terms for what happens at 1:45 is half time followed by an accelerando back up to the original tempo.

If, prior to 1:45, you start feeling every other beat, you will notice that the new tempo at 1:45 matches exactly. In other words, there is an instantaneous tempo change to half speed.

What occurs next is a gradual change in tempo that occurs over time. It is NOT notated as an adjustment to the rhythm. By the end of the song, the tempo has accelerated back to the original speed.

It is important to note that doubling the rhythmic length of each note while keeping the tempo static will sound the same as keeping the rhythmic length constant while halving the tempo. The reason I would not suggest doing that in this example is because the music accelerates back up to the original tempo, so if you simply double the rhythmic length and then accelerate, you will end up with a tempo twice the speed of what you started with even though the music is the same.

You may have heard of Shepard Tones, which sound as if they increase (or decrease) in pitch forever. What actually happens is that the tone is made up of a number of frequencies, reducing in loudness the further they are from the 'main' pitch range.

You could do it at a piano with five people (each using just one finger!). All stand at the piano, and each play a different C. The person in the middle plays loudest. The people at either end play very quietly. The 2nd and 4th people play at medium volume.

Now everybody goes up to C#, D, D#, E, F... when the person on the right runs out of keyboard, he runs around and plays a bass note. Keep doing that forever.

A Risset Rhythm does something very similar with rhythm. Imagine your drum loop fades in at (say) 1/16 speed, gradually increases in tempo and volume, until it's at full tempo and full volume. Then it continues to increase in tempo as it fades out again, until eventually it's silent. Now, layer that track with a copy of itself, delayed so that track 2 is half the tempo of track 1. And keep doing that forever.

It might help to think about what would happen if you tried to dance to it. If you hear a beat at 120bpm, you can choose to tap your foot twice a second (every beat), once a second (downbeats), once every two seconds (each bar), etc. With the Risset Rhythm, you might start tapping your feet twice a second. Then as the tempo increases, you find you're tapping your feet three times, then four times, then six times a second. Soon it'll be faster than you can tap, so you'll drop some taps and go back to twice a second. Repeat.

The link above takes you to some code for the SuperCollider sound programming language, and a sample of the effect.

As NReilingh has pointed out, however, that's not what happens in the Die Antwoord track. All that happens there is that they suddenly halve the tempo, then increase the tempo until they're back to the initial tempo.

There's yet another way to make an acceleration effect. A series of figures with increasing subdivisions. Like 2 eighth notes, then 4 sixteenths, then 2 eighth-valued figures of 16-th triplets, then 4 figures of 32-nd triplets. Usually you want to increase the division by a factor of 2 or 3 each time. So the actual tempo remains constant, by the time-interval between successive notes decreases dramatically.