Simplify the following text for a Grade 13 native English-speaking person.
Original: Her teachers have included Heidi Johanessen ( Norwegian National Opera Orchestra ) and since 2002 Arnulf Naur Nilsen ( Oslo Philharmonic Orchestra ) .
Simplified: She has studied under both Heidi Johanessen ( a member of the Norwegian National Opera Orchestra ) and , since 2002 , Arnulf Naur Nilsen ( member of the Oslo Philharmonic ) .