Related Clues:

• Lecture record
• Score rates
• Short messages
• Speeds at a concert
• Speaker's aids
• Music symbols
• Brief letters
• Flagship product from 21-Down
• Explanatory material
• Speeds for a 57-Across
• Scoring units
• What the starts of 17-, 34- and 61-Across are
• Do, re, mi, e.g.
• Writes down
• Do, re and mi, etc.