As we've seen, a sound wave's noise is determined by its height: the higher the wave, the louder the sound. A sound wave is also characterized by its length or the space between each wave's peak. Think of the distance between regular waves that lap against the shore. Sound waves with peaks very close together produce higher pitch sounds. That's because they are vibrating very quickly. Musical instruments like trumpets have high-pitched sounds and create sound waves that are close together. Conversely, sound waves with wave peaks further apart produce lower pitch sounds. These sound waves are vibrating more slowly. An oboe or bassoon are musical instruments with lower pitch.