Summary
Abnormal activity of the orbicularis oculi muscles concomitant with stammering was abolished at the same time as the speech disfluency by larynx-triggered auditory feedback masking. Similar abnormal muscular activity observed in two “exstammerers” exhibiting fluent speech at the time of testing was also abolished by the AFM device.
All of the eight stammerers tested using a hand control switch to the AFM device showed delays in operating the switch which reduced the effectiveness of auditory masking in suppressing stammer.