Answer:
Frequency determines the pitch we perceive. Amplitude determines the volume, and loudness perceived (see more detail below)
Explanation:
A most fundamental wave shape is the sine (or cosine). A sine wave has three parameters: (1) frequency, (2) phase, and (3) amplitude. Out of the three, two play a role in your question, as follows.
The frequency, namely the number of periods (repetitions) per second, is perceived by our ear of "the pitch." The higher the frequency, the higher the pitch. However, our ears perceive pitch as a logarithm of the physical frequency. Every doubling of the frequency causes us to hear the pitch to increase by one octave.
The volume is determined by the amplitude of the wave. The higher the amplitude (positive or negative) the higher the volume. Our ears perceive volume as "loudness" and, again, not linearly - some frequencies are perceived as louder than others, even though they have the same physical volume. Frequencies between about 200 and 2000 Hz are perceived as louder than the rest of the audible spectrum (between 20 and 20000 Hz).
Interestingly, the phase does not play all too prominent role in perception, at least as far as music and speech are concerned.
