Here's why:
* Tempo refers to the overall speed of speech. This includes both the length of individual sounds and the pauses between words and phrases.
* Duration is a component of tempo, specifically referring to the length of individual sounds.
* Tempo encompasses both duration and the overall pacing of speech, providing information about how quickly or slowly someone is speaking.
Other prosodic features include:
* Pitch: The highness or lowness of a speaker's voice.
* Stress: The emphasis placed on certain syllables or words.
* Intonation: The rise and fall of pitch in speech, often used to convey meaning or emotion.
While duration is a component of tempo, it's not the only factor. Tempo encompasses the overall rhythm and pacing of speech, which is influenced by both the length of individual sounds and the timing of pauses.