The effect of automatic speech recognition systems on speaking workload and task efficiency

This investigation explored the speech-production behaviors associated with the use of automatic speech recognition (ASR) software for dictation of spontaneous and scripted material by individuals with and without spinal cord injury (SCI). The variables of interest in determining speaking workload and efficiency included syllables per breath group, frequency of breath groups, frequency of apnea, time needed for dictation and number of words spoken during a dictation task.

Twelve individuals participated, six with SCI and six able-bodied cohorts matched for age, sex and height. Subjects dictated with continuous-speech ASR, discrete-word ASR and no ASR in a spontaneous-speaking situation, as well as in a scripted speaking situation.

For all variables, differences amongst dictation conditions were significant. No significant differences were found between speaker groups. Dictation with both discrete-word and continuous-speech ASR resulted in a decrease in the number of syllables produced per breath group, increases in the frequency of breath groups and apnea, with differences from normal being greater for dictation with discrete-word ASR. In addition, when participants dictated with either type of ASR, the amount of time and number of words produced were significantly greater than that associated with production of the same message without ASR, requiring 'more work' on the part of the speaker and ultimately reducing the efficiency with which a message was produced.

From a human factors perspective, these results suggest that ASR software, especially discrete-word ASR, has the potential to increase energy expenditure during dictation over a prolonged period of time, thereby increasing speech workloads and the potential for overuse of the laryngeal system.