Reducing excessive vocal loudness in persons with mental retardation through the use of a portable auditory-feedback device.

A simple portable device was used to reduce excessive vocal loudness in two adults affected by moderate mental retardation. The device provided these adults with auditory feedback (a pulsating tone of about 300 Hz and 80 dB) when their vocal loudness exceeded a preset limit. Data showed that the device was effective in helping the two adults reduce their excessive vocal loudness. The use of the device continued to produce positive effects over time. Implications of these findings are discussed.