Wavering p. pr. & vb. n. : of Waver

Example:
How can I stop my pitch from quavering and Wavering and being unsteady when I sing a long held note?

Taxonomy
waver, Merriam-Webster Online Dictionary, Dictionary, webster, Word Games, Webster Online Dictionary with audio pronunciations, thesaurus, Middle English, Old English, wave, glossary, english, language, ESL, Search, intransitive verb, Inflected, vered.

Defination from the web:
waver from the Merriam-Webster Online Dictionary with audio pronunciations, thesaurus, Word of the Day, and word games. ... 2 a : to weave or sway unsteadily to and fro : reel, totter b : quiver, flicker <wavering flames> c : to hesitate as if about to give way : falter ...