Aspects of communication which affect the meaning of a vocal message, which strictly speaking, is not language. Tone of voice, inflection, pauses, etc. are examples of processes which affect how a message is received by a listener.
Paralanguage refers to the non-verbal elements of communication used to modify meaning and convey emotion. Paralanguage may be expressed consciously or unconsciously, and it includes pitch, volume, and intonation of speech. Sometimes the definition is restricted to vocally-produced sounds.