Purpose: The purpose of this study was to better understand neck intermuscular beta coherence (15-35 Hz; NIBcoh) in healthy individuals, with respect to modulation by behavioral tasks.
Method: Mean NIBcoh was measured using surface electromyography at 2 anterior neck locations in 10 individuals during normal speech, static nonspeech maneuvers, "clear" speech (intentionally produced to maximize intelligibility), divided-attention speech, singing, and mimicked hyperfunctional speech.
Results: An analysis of variance showed significant effects of both individual and condition (p = .001) on the mean beta-band intermuscular coherence. Dunnett's simultaneous paired t tests found decreased NIBcoh during low-attention speech, singing, and hyperfunctional speech (p(adj) < .05), but no significant difference in NIBcoh during nonspeech tasks or clear speech production relative to normal speech.
Conclusions: Compared with normal speech, mean NIBcoh was decreased in a divided-attention speech task, but clear speech did not result in increased mean coherence relative to normal speech, possibly due to ceiling effects caused by heightened attention and precision during experimental recording. Mimicking a strained, hyperfunctional voice resulted in a reduction in mean beta intermuscular coherence quantitatively and qualitatively similar to the lowered values of mean beta coherence seen in individuals with vocal nodules relative to individuals with normal voice.