Simplify the following text for a Grade 8 native English-speaking person.
Original: Some bass-baritones are baritones , like Friedrich Schorr , George London , James Morris and Bryn Terfel .
Simplified: Some baritones have voices not quite low enough to be a true bass , and prefer to call themselves bass-baritones . Bryn Terfel is a famous Welsh bass-baritone .