If we increase the amount of air that is compacted in each sound wave but keep the same number of waves, then we have changed the:

A) timbre.
B) pitch.
C) amplitude.
D) frequency.

Amplitude

The magnitude or extent of oscillation in a wave or periodic function.

Air

The invisible gaseous substance surrounding the Earth, a mixture mainly of oxygen and nitrogen.

Sound Wave

Mechanical displacement of molecules caused by changing pressure that possesses the physical properties of frequency, amplitude, and complexity. Also referred to as a compression wave.