I see you chose the triangle wave, sometimes called a sawtooth wave. To most people, the square wave sounds like a noisy buzzer, while the sine wave sounds like a “pure tone.” The triangle wave usually has both some of the noise quality of a square wave and some of the tonal quality of a sine wave. As we will see later, the sine wave really is the purest of all tones.

Now we'll introduce another important characteristic of sound. Examine the two sounds below carefully. What is the difference between these two sounds?

1. The lower crests are moving faster than the upper crests
2. The lower crests are further apart than the upper crests
3. The lower crests are closer together than the upper crests
4. None of the above