Respiratory control in stuttering speakers: Evidence from respiratory high-frequency oscillations

This study tested the hypothesis that, in stuttering speakers, relations be tween the neural control systems for speech and life support, or metabolic breathing, may differ from relations previously observed in normally fluent subjects. Bilaterally coherent high-frequency oscillations in inspiratory- related EMGs, measured as maximum coherence in the Frequency band of 60-110 Hz (MC-HFO), were used as indicators of participation by the brainstem con troller for metabolic breathing in 10 normally fluent and 10 stuttering spe akers. In all controls and most stuttering subjects, MC-HFO for speech was higher than or comparable to MC-HFO for deep breathing. For 4 stuttering su bjects, higher MC-HFO was observed For speech than for deep breathing. Comp arison of deep breathing to a speechlike breathing task yielded similar res ults. No relationship between MC-HFO during speech and severity of disfluen cy was observed. We conclude that in some stuttering speakers, the relation s between respiratory controllers are atypical, but that high participation by the HFO-producing circuitry in the brainstem during speech is not suffi cient to disrupt fluency.