Pitch is one of the three subjective attributes of sound.
That is to say our auditory system provides us with sensations caused by changes in air pressure, and those sensations seem to vary along three basic dimensions of loudness, pitch and timbre. Thus when we hear two sounds that are different, we can associate those differences to a change in loudness, a change in pitch, a change in timbre, or some combination of these. When we sing we try to make noises that change in pitch in the same proportions as musical instruments change in pitch. Pitch doesn't tell us about the shape of the cycles, only how often they repeat. Timbre has a technical and a non-technical definition.