the tone of a sound
timbre - tone
The formal word ‘timbre' refers to the particular quality of a sound that makes it distinct from others. It is most commonly used in relation to that of a voice or musical instrument. This term is most likely to be encountered in written English as in conversation one would be more likely to use the less formal 'tone’.
The radio DJ has a soothing, reassuring timbre to his voice. That’s why he’s so popular with the audience.
When Clare gave Sam the bad news, there was a sad timbre to her voice. She was clearly very upset.
The timbre of that instrument is like nothing I have ever heard before. That's why I simply had to buy it.