The Lombard sign as a function of age and task.

The Lombard sign was investigated as a function of age and task. Twenty adults and 20 5-year-old children spoke in quiet and in the presence of a 90-dB SPL noise. Half the subjects labelled a series of pictures, half told stories about the pictures. All subjects increased vocal intensity in the presence of noise. Children increased intensity equally in both tasks. Adults increased intensity more during the story-telling task than during the labelling task.