Each intonational phrase has precisely one tonic syllable or focus, which is distinguished from the rest of the linguistic string by specific phonetic properties that manifest as a beat.
prehead tonic [ tail ] Noting the phonetic properties that distinguish the tonic from the rest of the linguistic string helps us make sense of the subtle issues of timing, emphasis, and pitch that alter our articulation of each of these sentences.
For while tonicity is probably the most recognized component of intonation, few among us can pinpoint what distinguishes the tonic from the rest of the linguistic string in which it appears.