Possible Clues:

• Reliable path for a film extra
• It's generally inaudible to the characters
• Sensible course to follow in cinema, we hear
• Accompaniment 6 need to minimise half of 14
• Audio recording for film
• Groundsmen may be paid to deliver this recording
• Film score
• Healthy dog -- something heard in film?
• Audio to a film
• Supporting music in reliable way