An example of monotonous is the science teacher's voice in "The Wonder Years."
A monotonous droning voice.
Jonny's voice was coldly monotonous but soft.
The notes of the blackbird are rich and full, but monotonous as compared with those of the song-thrush.
As professional story-tellers many Moors are remarkable, but the national music is monotonous and not very harmonious.
"I know, I know," answered Prince Vasili in his monotonous voice.
She shivered, sensing something truly evil in his monotonous voice and cold hands.