Click here to purchase the entire book in PDF format. Harmonics If we go back to the clarinet example, it's pretty obvious that the pressure wave that comes out the bell won't be a sine wave. This is because the clarinet reed is doing more than simply opening and closing - it's also wiggling and flapping a bit - on top of all that, the body of the clarinet is resonating various frequencies as well (more on this topic later), so what comes out is a bunch of different frequencies simultaneously. We call these other frequencies harmonics which are mathematically related to the bottom frequency (called the fundamental) by simple multiplication... The first harmonic is the fundamental. The second harmonic is twice the frequency of the fundamental, the third harmonic is three times the frequency of the fundamental and so on. (This is an oversimplification that we'll straighten out later...)