If the speaker wants to make one word of the descending head more prominent than the others he pronounces it a little higher than the preceding syllables thus breaking their descending succession. This non-final rise is called accidental. It never occurs on the first stressed syllable as the syllable is always the highest in the descending head. Eg:↓Tom ꞌBrown is the ↑best ꞌpupil in ˎclass.