They both possess a light, slightly nasal voice, but whereas Siffre has his excellent guitar work to back up his vocals, O'Sullivan only has that same old plonky piano and his arranger.
Source: wiktionary
Plonky
Synonyms for "plonky"
Ranked by relevance and common usage.
Sample sentences
2 total sentences available.
Clement Ishmael's plodding arrangements for lone, plonky piano, and the unlovely voices of two-thirds of the cast, do not help: even a sublimely sexy song like You Can Leave Your Hat On is rendered flat and toneless.
Source: wiktionary