Reaffirmed 2023

NATIONAL FOREWORD

This Indian Standard which is identical with ISO 24504 : 2014 ‘Ergonomics — Accessible design — Sound pressure levels of spoken announcements for products and public address systems’ issued by the International Organization for Standardization (ISO) was adopted by the Bureau of Indian Standards on the recommendation of the Ergonomics Sectional Committee and approval of the Production and General Engineering Division Council.

Today, people conduct their daily lives along with spoken announcements from various products such as home electrical appliances, information and telecommunication products, office-automation equipment, heating equipment, toys, sanitary equipment, and health care products. Some products use spoken announcements to provide instructions in indoor and outdoor public areas such as ticket vending machines, elevators, and escalators. Public address systems are often installed to provide spoken announcements. Such announcements can be indistinct to listeners because of hearing loss that can occur with ageing or because of ambient noise in the surroundings.

This Indian Standard specifies methods for determining an appropriate sound level range of spoken announcements so that all listeners, including people with age-related hearing loss, can hear them properly against ambient noises. This sound level range specification was determined based on results of experiments in which people of different ages participated. Spoken announcements for which sound pressure levels are within the range specified in this Indian Standard are expected to be audible and comfortably loud for most users in the presence of ambient noise.

This Indian Standard is intended to be applied as necessary to products depending on the product type and its conditions of use. It does not apply to spoken announcements used for evacuation or emergency purposes.

ISO 9921 specifies recommended levels of speech-communication quality necessary for conveying comprehensive messages in different applications. Therefore, ISO 9921 differs from this Indian Standard.

This Indian Standard adopts the principles of accessible design from ISO/IEC Guide 71, which are amplified in ISO/TR 22411.

The text of ISO Standard has been approved as suitable for publication as an Indian Standard without deviations. Certain terminology and conventions are, however, not identical to those used in Indian Standards. Attention is particularly drawn to the following:

a) Wherever the words ‘International Standard’ appear referring to this standard, they should be read as ‘Indian Standard’.

b) Comma (,) has been used as a decimal marker while in Indian Standards, the current practice is to use a point (.) as the decimal marker.