How is pitch defined?

Pitch is defined as the listener's perception of how high or low a sound is. This concept is fundamentally tied to the frequency of the sound waves produced; higher frequencies are perceived as higher pitches, while lower frequencies are perceived as lower pitches.

Understanding pitch is crucial in speech and communication because it plays a significant role in conveying emotions, intentions, and grammatical distinctions in language. For example, variations in pitch can indicate questions, statements, or exclamations in spoken language.

The other options relate to different aspects of sound but do not define pitch accurately. The volume of sound refers to its amplitude and how loud or soft it is, capacity of voice pertains more to the physical abilities of the voice, and the quality of voice involves characteristics like timbre and resonance, which influence how the voice is perceived but aren't directly related to pitch. Thus, option C is the most accurate description of pitch.