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Threshold
The least exposure that has a measurable effect on unexposed film. 1
The threshold of ‘hearing’ is the sound pressure level at which people hear only 50 per cent of the time. Approximately 0 dB SPL at 1 KHz.
The threshold of ‘feeling’ is the sound pressure level at which people feel discomfort 50 per cent of the time. Approximately 118 dB SPL at 1 KHz.
The threshold of ‘pain’ is the sound pressure level at which people feel actual pain 50 per cent of the time. Approximately 140 dB SPL at 1 KHz.
References
1 Case, D., 1985, Motion Picture Film Processing, Media Manuals, Focal Press, London, Boston
The National Film and Sound Archive of Australia acknowledges Australia’s Aboriginal and Torres Strait Islander peoples as the Traditional Custodians of the land on which we work and live and gives respect to their Elders both past and present.