Question

One sound is loud and another is quieter. What must be different about these two sound waves?

Their frequencies

The amplitudes

Their wavelengths

Their pitches

Answer 1

AMPLITUDE

Answer 2

a trig cosine or sine is bound at a range of -1 to 1, to go any larger on the y axis, you need to multiply the sin or cosine by some amplitude constant

y = A*sin(...)