boso-boso
Talking in a barely audible, monotone voice that is difficult to hear. Often conveys shyness, lack of confidence, or reluctance to speak.
💡A shy student giving a presentation — 'He spoke boso-boso and nobody could hear.'
彼はぼそぼそと小さい声で話す。
He speaks boso-boso in a tiny voice.
She answered the question ___ so the teacher asked her to repeat.
彼女は○○と答えたので先生に聞き返された。