tunelessly       
adverb uk/ˈtʃuːn.ləs.li/ us/ˈtuːn.ləs.li/
 不成曲调地;不悦耳地
in a way that has no tune and does not sound pleasant
  She sang rather tunelessly. 她唱得不太入调。 
 He began to whistle tunelessly.  他开始怪腔怪调地吹口哨。 
 See: tuneless
 - More examples
 - A voice echoed tunelessly from the passage.
 - He began to sing loudly and tunelessly against the roar of the engine.
 - Michael, beside Stephen, began to hum tunelessly.