Turn on the radio or surf YouTube for music, and you’re bound to run into a remix of a song you already know. Remixes of songs can change the music or beat or insert new verses by rappers (often to try to get a song more airplay — Nicki Minaj doesn’t get a quarter million for a verse for no reason!). Sometimes a DJ might combine two different songs to make a new work, sometimes called a “mash-up.” DJs like Girl Talk or DJ Earworm have become popular taking anywhere between two and twenty-five different songs and mashing them together into new ones.
The secret behind beat-matching is knowing the math.
What you might not know, though, is that remixing is a process that requires careful mathematical calculations. Every song has its own tempo, or speed, and usually songs that might sound like they share a tempo are still slightly different. Beats per minute or BPM tells us exactly how fast or slow a song is. If you try to put an element of one song on top of an element of another one — mixing and matching beats, rap verses, or melodies — you’ll find that songs with different BPMs won’t match, and what you’ll hear is a total mess.
Although some software will automatically “beat match” different songs, slowing down or speeding up two songs so that they have the same BPM, the secret behind beat-matching is knowing the math. What computer programs now do automatically, DJs once had to do themselves, slowing down or speeding up one song to match the tempo of another. By understanding how this math works, you’ll be one step closer to really knowing how popular remixes really work. What songs would sound better faster or slower? How much would you need to speed them up or slow them down to get the effect you’re looking for? These creative decisions would be impossible without the mathematical knowledge to back it up.