Effects of Speech Intelligibility Level on Concurrent Visual Task Performance

Abstract

Four experiments were performed to determine if changes in the level of speech intelligibility in an auditory task have an impact on performance in concurrent visual tasks. The auditory task used in each experiment was a memory search task in which subjects memorized a set of words and then decided whether authority presented probe items were members of the memorized set. The visual tasks used were an unstable tracking task, a spatial decision-making task, a mathematical reasoning task, and a probability monitoring task. Results showed that performance on the unstable tracking and probability monitoring tasks was unaffected by the level of speech intelligibility on the auditory task, whereas accuracy in the spatial decision-making and mathematical processing tasks was significantly worse at low speech intelligibility levels. The findings are interpreted within the framework of multiple resource theory.

The Effect of Auditory and Visual Distracters on the Useful Field of View: Implications for the Driving Task

“…Turatto et al 4 postulated that the auditory and visual response selection could not be shared across modalities, and attentional resources used for auditory responses detract from the central processing of the visual task. Payne et al 20 investigated the effect of a concurrent speech intelligibility task on several visual tasks and also concluded that higher-level cognitive sites are an important source of interference in auditory and visual dual tasks. They reported that interference among the auditory and visual tasks was "restricted to those visual tasks that tapped into the central processes of memory and decision-making (i.e., spatial processing, math processing)".…”

Speech intelligibility in hospitals

“…One military study explored how speech intelligibility levels can affect visual task performance. 33 Researchers found that speech intelligibility impacted performance levels in a visual task that required use of short term memory and decision making, based on a sample of 28 subjects. However, intelligibility did not affect performance in a visual tracking task.…”

Impact of speech presentation level on cognitive task performance: implications for auditory display design

“…Pickett (1956) found that speech intelligibility remains relatively constant as speakers increase their vocal force from 50 to 78 dB, but diminishes above and below this range. Speech intelligibility has also been examined under less ideal conditions such as with degradation due to a chopping circuit that intermittently cuts out portions of the verbal message (Payne et al 1994), in the presence of noise (Broadbent 1958, Kryter, 1972, 1985, for synthetic speech (Robinson andEberts 1987, also see Simpson et al 1985 for a review of this literature) and under conditions of electronic versus natural ampli®cation (Tschopp and Beckenbauer 1991). Despite the abundance of literature on speech intelligibility under diverse conditions, the potential of intensity to alter processing requirements of speech stimuli has gained little attention.…”