Quaver (verb)

1. To produce a trembling or vibrating sound.
2. To speak or sing with a quivering or trembling voice.

Origin:

Late middle english (as a verb): from old french quaverer, of imitative origin.

Examples:

1. The singer's voice quavered as she sang the high notes.
2. The old man's voice quavered as he told his story.
3. The violinist's hand quavered as she played the difficult passage.
4. The earthquake caused the building to quaver and shake.
5. The wind quavered the branches of the tree.