Dic: a note of some feeling in someone's voice

• There is an unmistakable note of nostalgia in his voice when he looks back on the early years of the family business.     
• It was not difficult for him to catch the note of bitterness in my voice.

N-SING : with supp, usu N of n | You can use note to refer to a particular quality in someone's voice that shows how they are feeling. (= tone)

.... Cobuild