mono·tone 
/ˈmɑ:nəˌtoʊn/ noun
/ˈmɑ:nəˌtoʊn/ noun [singular] : a way of talking or singing without raising or lowering the sound of your voice
▪ She read the story in a dull monotone. ▪ He sang in a soft, low monotone. ▪ She spoke in a monotone voice.
▪ She read the story in a dull monotone. ▪ He sang in a soft, low monotone. ▪ She spoke in a monotone voice.
