Click here to purchase the entire book in PDF format. Time vs. Frequency We said earlier that the upper harmonics of a periodic waveform are multiples of the first harmonic. Therefore, if I have a non-sinusoidal, but periodic waveform, with a fundamental of 100 Hz, the actual harmonic content is 100 Hz, 200 Hz, 300 Hz, 400 Hz and so on up to $\infty$ Hz. Let's assume that the fundamental is lowered to 1 Hz - we're now dealing with an object that is being struck 1 time each second. The fundamental is 1 Hz, so the upper harmonics are 2 Hz, 3 Hz, 4 Hz, 5 Hz and so on up to $\infty$. If we keep slowing down the fundamental to one single strike, then the harmonic content is all frequencies up to infinity. Therefore it takes all frequencies sounding simultaneously with the correct phase relationships to create a single click. If we were to graph this relationship, it would be Figure 3.13, where the two graphs essentially show the same information. Figure 3.13: Two graphs showing exactly the same information. An infinitely short amplitude spike in the time domain is equivalent of all frequencies being present at that moment in time.