Simplify the following text for a Grade 9 native English-speaking person.
Original: However , the most common application of the term `` vocal range '' is within the context of singing , where it is used as one of the major defining characteristics for classifying singing voices into groups known as voice types .
Simplified: However , the most common use of the term `` vocal range '' is in singing , where it is used for classifying singing voices into groups .