ISO 24504:2014 specifies methods to determine an appropriate sound pressure level range for spoken announcements in environments where ambient noise is less than 80 dB. The specified methods follow the concepts of ISO/IEC Guide 71 and includes consideration of older persons with decreased hearing ability to determine sound pressure levels of spoken announcements. The spoken speech levels specified are for products and public-address systems. ISO 24504:2014 is applicable when a loudspeaker producing a spoken announcement is located a short distance from the user in an environment where the sound pressure level with a standard frequency weighting A of ambient noise does not exceed 80 dB. It is applicable to spoken announcements that are audible to persons with normal hearing for their age when presented by a target product under quiet and anechoic conditions, and for both recorded voice and synthetic speech announcements. It is not applicable to products providing private information such as automated teller machines in public spaces, nor to spoken announcements heard through headphones or earphones, or with the ear close to the speech sound source such as ear speakers. It does not specify the sound pressure levels of spoken announcements for systems with automatic sound pressure level control to compensate for fluctuating ambient noise levels, nor those presented in emergency situations such as signals for fire alarms, gas leakage and crime prevention (covered in ISO 7240-16 and ISO 7240-19), or in automobiles (covered in ISO 15006). It considers only the audibility of speech and not the process of speech understanding.
Tämän julkaisun valmistelusta Suomessa vastaa Metalliteollisuuden Standardisointiyhdistys ry, puh. 09 19 231 (vaihde).
Sisällysluettelo
Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols
5 Range of sound pressure level of spoken announcements
5.1 General
5.2 Criteria to determine the speech level
5.3 Relevant factors related to speech perception
5.4 A-weighted sound pressure level method to determine the speech level
5.5 Simplified STI method to determine the minimum speech level
Annex A Method for measuring the sound pressure level of spoken announcements and ambient noise (normative)
Annex B Effects of age-related hearing loss on word recognition (informative)
Annex C Examples of measurement condition and result records (informative)
Annex D STI method to determine minimum speech level (informative)
IEC 60050-801:1994
IEC 60268-16:2011
IEC 61260:1995
IEC 61672-1:2013
ISO 1996-1:2016 Acoustics -- Description, measurement and assessment of environmental noise -- Part 1: Basic quantities and assessment procedures
ISO 3382-2:2008 Acoustics -- Measurement of room acoustic parameters -- Part 2: Reverberation time in ordinary rooms
ISO 389-1:1998 Acoustics -- Reference zero for the calibration of audiometric equipment -- Part 1: Reference equivalent threshold sound pressure levels for pure tones and supra-aural earphones
ISO 8253-1:2010 Acoustics -- Audiometric test methods -- Part 1: Pure-tone air and bone conduction audiometry