M00000206
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ISO 24504 1st Edition, August 1, 2014 Ergonomics - Accessible design - Sound pressure levels of spoken announcements for products and public address systems
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Availability date: 07/13/2021
Description / Abstract:
This International Standard 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 that are specified in this International Standard are
for procucts and public-address systems. To improve the
accessibility and usability of products, spoken announements must
not only be audible but also presented at comfortable speech
levels.
The target products that present spoken announcements are
consumer products such as electronic home appliances, information
and communication technology services, and products providing
services for general users in public facilities indoors and
outdoors such as train stations, airports, meeting rooms, amusement
parks, and fairs.
This International Standard is not applicable to products
providing private information such as automated teller machines in
public spaces.
This International Standard 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. This International Standard 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. This International Standard is applicable for
both recorded voice and synthetic speech announcements.
This International Standard does not specify sound pressure
levels of spoken announcements for systems with automatic sound
pressure level control to compensate for fluctuating ambient noise
levels. This International Standard is not applicable to spoken
announcements heard through headphones or earphones, or to spoken
announcements heard with the ear close to the speech sound source,
such as in ear speakers specified in IEC 60268-7. This
International Standard considers only the audibility of speech and
not the process of speech understanding.
This International Standard does not specify the sound pressure
levels of spoken announcements presented in emergency situations
such as signals for fire alarms, gas leakage, and crime prevention;
those are covered in ISO 7240-16 and ISO 7240-19. This
International Standard does not specify the sound pressure levels
of spoken announcements in automobiles; those are covered in ISO
15006.
NOTE 1 A spoken announcement presented in a repetitive manner
from a product such as electronic home appliance is presumed to be
heard as an auditory sign but not as a message and is therefore
usable with a lower sound pressure level of the spoken announcement
than this International Standard specifies.
NOTE 2 It is known that the word recognition performance of
native speakers of the language of the announcement is better than
that of non-active speakers.