老师的声音怎么说英语

In English, you can say "teacher's voice" to refer to the sound of a teacher speaking. You could also say "the sound of the teacher's voice" if you wanted to be more specific. For example:
"I could hear the teacher's voice coming from the classroom down the hallway."
"The sound of the teacher's voice was calm and reassuring as she explained the lesson."
You could also use the word "lecturer" instead of "teacher" if the person you are referring to is a college or university instructor.