Audio Input
A telephone with a sensitive microphone will help persons with quiet voices or with restricted neck and chest movement that makes speaking difficult. It is also important for the user to be able to adjust the sensitivity of the microphone so that it can be used by either a person with a weak voice or a normal voice.
Amplification
of the microphone should be user controlled and should reset on call termination.
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 (eg when hand tremor interferes with manual keying). Useful for dyslexic users who can read aloud and simultaneously dial a number thus avoiding short-term memory problems. Such systems could be limited to just the numerals or a few words such as 'doctor' or 'Jane'.
Speech
Voice control can be beneficial in situations where more than one task is performed simultaneously which require both hand and/or eye co-ordination. Audio output can convey information about the system. It's limitations include technological contraints which limit the vocabulary size and speed of accurate processing. Feedback of a mistake may interrupt other activites. The acoustic quality and noise must be monitored and optimised. The audio components must be compatible with the rest of the system.
Most speech input systems can only handle a limited vocabulary. The larger the vocabulary, the lower the recognition accuracy and the slower the processing. Co-articulation of natural speech is difficult for a machine to decipher so it misinterprets the words. Each word must be preceeded by a pause. Other non-verbal sounds such as coughs or mumbles may be incorrectly accepted as responses. People's voices change with their mood. Strong accented voices may be frequently misunderstood or not recognised.
Recommendations
- Minimise background noise.
- Ensure that the microphone can be used by people in wheelchairs as well as by people standing in front of the terminal.
- Provide alternative method of input for people with a speech impairment (or with a strong accent).
- Provide recognition feedback after each input.
- Provide opportunity for the user to undo incorrect inputs.
Further information