Summary PurposeThe purpose of the present study was to determine the extrinsic laryngeal muscle activity and vocal economy during two different singing conditions (straight-tone singing vs. vibrato singing) over a physiologically relevant singing range. MethodsThirty professional singers or voice coaches participated in the study. The participants sang a sustained /a:/ vowel for approximately 5 seconds, once in straight-tone singing conditions and once more in vibrato. The target pitches were C3, F3, A3, C4, F4, A4, and C5. Surface electromyographic (sEMG) measures were performed in the infrahyoid (IH) muscle region and the suprahyoid (SH) muscle region. Contact quotient (CQ), sound pressure level (SPL), and fundamental frequencies were measured to derive the electroglottographic-based vocal economy parameter quasi-output cost ratio (QOCR). ResultssEMG measures show that IH and SH muscles significantly increased in activity with ascending pitch. IH and SH muscle activity were significantly higher when singing in vibrato than straight-tone. Moreover, SPL also increased with ascending pitch and when sung in vibrato. CQ increased and QOCR decreased as pitch ascended but did not significantly change when sung in vibrato. ConclusionSinging higher pitches were generally associated with higher extrinsic laryngeal muscle activity and lower QOCR values. When comparing the two singing conditions, the extrinsic laryngeal muscle activity was higher during vibrato, implicating that the IH and the SH muscles may contribute to rhythmic pulsations of pitch changes. Although the QOCR value did not show significant differences between the two singing conditions, a significantly high SPL during vibrato may indicate acoustical and physiological advantages while singing in vibrato.
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