Final answer:
Intonation is the nonverbal communication technique that causes the speaker's voice to rise and fall.
Step-by-step explanation:
The nonverbal communication technique that causes the speaker's voice to rise and fall is called intonation. Intonation refers to the variation in pitch while speaking and is used to convey different meanings or emotions. For example, when asking a question, the voice typically rises at the end of the sentence, while expressing surprise or excitement may involve a sudden increase in pitch.
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