This International Standard specifies ergonomic requirements and recommendations of spoken instructions for consumer products that are used as a means of instructions for operations or feedback of the status of products when used by a person with or without visual impairments. NOTE 1 Spoken instructions are also useful for some users who have difficulty in reading and those with cognitive impairment. The requirements and recommendations described in this standard do not depend on the language of guides and are applicable to conventional, stand-alone consumer products in general whose function is limited by characteristics that prevent the user from attaching, installing or using assistive technology. They are not applied to machines and equipment used for professional work. This document is applicable to spoken instructions of both recorded human speech and synthesized speech from text. This document does not apply to products for which the instructional content and/or the means of presentation are regulated by law or specified in other standards (e.g. medical devices, fire alarms). It also does not provide recommendations or requirements for spoken instructions of Interactive Voice Response (IVR) systems or digital assistants on personal computers or similar devices. NOTE 2 ISO 9241-154 provides recommendations or requirements for IVR systems. NOTE 3 ISO/TS 9241-126 provides generic guidance for the auditory presentation of information in interactive systems. This document does not specify voice sounds of text-to-speech systems or narrative speech used in place of printed instruction manuals and independently from the product.