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Audio Input

Picture showing headphones with an attached microphone resting on a keyboard.Audio input devices allow a user to send audio signals to a computer for processing, recording or carrying out commands. Audio input devices such as microphones allow users to speak to the computer in order to record a voice message or navigate software.

Aside from recording, audio input devices are also used with speech recognition software. In this case a microphone is used to speak to the software. Once the software is trained to recognise the user's voice, it can carry out commands for them rather than have them use a keyboard. When they dictate a letter, for example, speech recognition software can translate their spoken words into a written document. This is ideal for anyone who has a related disability.

Audio input devices add a great deal of flexibility and functionality to the computer. High-end sound cards might offer more interface ports for audio input devices than budget cards.


Microphones

A microphone is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. They typically have a limited pick-up range.

Picture of a telephone handset.Microphones can be found within a device (e.g. telephone handsets and computers); they can be tabletop or body worn (e.g. for mobile telephones) or in headsets.

Speech recognition

Speech recognition (also known as automatic speech recognition or computer speech recognition) uses software to convert spoken words to machine-readable input. The term "voice recognition" may also be used to refer to speech recognition, but can more precisely refer to speaker recognition, which attempts to identify the person speaking, as opposed to what is being said.

Speech recognition applications include for example, voice dialing (e.g. "Call home"), home appliances control, simple data entry (e.g. entering a credit card number) and speech-to-text processing.

Picture showing how the phrase can you recognise speech? be heard as can you wreck a nice beach?Concerning a telephone, speech-input keying is a useful means of providing a hands-free call set-up for users with reliable voice, and may be valuable even where full hands-free operation is not necessary (e.g. when hand tremor interferes with manual keying). Useful for dyslexsic users who can read aloud and simultaneously dial a number thus avoiding short-term memory problems.

Problems encountered by disabled people and the ageing population using audio input technology

Blind and partially sighted

Users with visual impairments may be unable to continue using audio input technology unless, recognition feedback has been provided as well as the opportunity to undo incorrect input.

Hearing impaired

Background noise may cause problems for hearing impaired users from supplying a system with a command.

Physically impaired

Wheelchair users and users with restricted neck and chest movements that makes speaking difficult, may be unable to use a microphone.

Cognitively impaired

Users with a speech impairment will be unable to use speech recognition technology therefore an alternative method of input will have to be provided.

Background noise may hinder users from providing spoken instructions or commands.

Some users may be unable to continue using audio input technology unless recognition feedback has been provided as well as the opportunity to undo incorrect input.

Ageing population

Members of the ageing population can experience a range of the problems mentioned above due to reduced physical, sensory or cognitive abilities that come with advancing age. For example, those that use wheelchairs may not be able to use a microphone.

Checklist for Audio Input

Recommendations

Microphones

  • Ensure that the microphone can be used by people in wheelchairs as well as by people standing in front of the terminal
  • Minimise background noise
  • Adjustable sensitive microphone
  • Amplification of the microphone should be user controlled
  • Microphone should reset after each user

Speech recognition

  • Provide alternative method of input for people with a speech impairment (or with a strong accent)
  • Use a limited vocabularly of simple words
  • Use longer rather than short monosyllabic words
  • Minimise background noise
  • Provide recognition feedback after each input
  • Provide opportunity for the user to undo incorrect inputs

Legislation

  • ETSI EG 202 116 (2002) Human Factors (HF); Guidelines for ICT products and services: Design for all
  • ISO/TR 22411 (2008) Ergonomics data and guidelines for the application of ISO/IEC Guide 71 to products and services to address the needs of older persons and persons with disabilities

Further information

Acknowledgements