Loud Movie Sound Is Dangerous, According to British Standards Insitute

Following new regulations to limit the volume of trailers shown before the main feature in cinemas by the Trailer Audio Standards Association (TASA), a new study by the British Standards Institute (BSI) warns moviegoers about the potential hearing damage due to prolonged exposure to loud movie sound. The BSI, an independent standards watchdog, conducted a year-long survey on the loudness of trailers and commercial advertisements, and now has published a draft standard to control and limit cinema sound levels in Britain. The proposal recommends that advertisements and trailers should average a sound pressure level (SPL) of 85 decibels (dB).The BSI has found several films, including Lethal Weapon 4, Godzilla, and Star Wars: Episode I - The Phantom Menace to have SPLís exceeding 100 dB, with Armageddon as the worst offender with 110 dB.The standard mandated by TASA in the USA, as of June 1, 1999, is a maximum average SPL of 87 dB. Trailers that exceed this limit must be remixed to meet this standard prior to theatrical release, or else the Motion Picture Association of America will not grant a rating to the film.The problem of loud trailers and films is the result of the exploitation of digital sound technology ñ the ability to deliver audio at unprecedented volume levels. In the past few years, the increasingly competitive movie business has believed that increasing the loudness of trailers will grab the audienceís attention.The Dolby Laboratories Model 737 Loudness Meter is used by TASA and the BSI to quantify the loudness of a filmís soundtrack, by averaging the SPL measured over the duration of the trailer or advertisement, and weighing the frequency response of the audio in relevance to human perception of sound.For more information on the issues concerning the excessive loudness of trailers, see the feature article in Issue 33 of Widescreen Review.