Tessitura

The range of a person's voice or the range of an instrument. A high tessitura means that they are using the higher part of their pitch range, so a low tessitura means they are using the lower part. A wide tessitura means that they have a large range (this is in comparison to the average instrument or voice's range, those playing in that piece of music, or that instrument / voice's usual range).

You've got quite a high tessitura!