Answer:
paralanguage.
Explanation:
Paralanguage can be defined as the non-verbal or non-lexical component (feature) of communication through a speech, typically used to convey emotions and modify its meaning.
Basically, paralanguage comprises of non-verbal or non-lexical elements such as pitch, intonation (tone or accent), manner or speed of speaking (speech rate), volume, modulation, etc.
Hence, Francis utilized paralanguage to enhance his speech at a union meeting by changing tone and pitch to call attention to his main arguments.
