Previous research has demonstrated the theoretical and clinical significance of the speech distortions associated with binaural presentation of delayed sidetone. Changes in vocal intensity, quality, and pitch, as well as deterioration in articulatory patterns resulting from delayed sidetone interference, have been investigated and reported in detail.
It has been established that an amplified sidetone having a signal delay ranging from 0.14 to 0.18 second can produce maximal disruption of speech production,1 and these changes can manifest themselves with delayed sidetone presentation levels as low as 20 db. re subject threshold for speech.2 At higher presentation levels, e. g., 40 db. and upward, voice and articulatory dysfunctions become increasingly spectacular and disruptive to oral communication.
Although quantification of these alterations in vocal and articulatory functions has been investigated, as yet the most readily measured effect of delayed sidetone interference with speech is a single resultant of the combined voice
RICHARD A. WINCHESTER, EDWARD W. GIBBONS. Relative Effectiveness of Three Modes of Delayed Sidetone Presentation. AMA Arch Otolaryngol. 1957;65(3):275–279. doi:10.1001/archotol.1957.03830210073011