This addresses the duration question: http://www.nhs.uk/Livewell/hearing-problems/Pages/tips-to-protect-hearing.aspx http://www.nhs.uk/Livewell/hearing-problems

This addresses the duration question: http://www.nhs.uk/Livewell/hearing-problems/Pages/tips-to-protect-hearing.aspx http://www.nhs.uk/Livewell/hearing-problems/Pages/tips-to-pr...