Influence of Glottal Fry on Acoustic Voice Assessment: A Preliminary Study

SummaryPurposeThis preliminary study examined the influence of glottal fry on measurement of speaking fundamental frequency (SF0) and whether sex differences influence the impact glottal fry has on SF0 and cepstral peak prominence (CPP). It was hypothesized that SF0 and CPP would decrease as percent glottal fry in the sample increased, with larger changes observed in the female voice.MethodsTwenty-six participants (13 men, 13 women) completed the study. Participants were recorded reading the Rainbow Passage. SF0 and CPP were determined from the original sample. Percent glottal fry SF0 was determined and semitone change was recalculated after removal of glottal fry from the sample. Regression analysis was used to determine the impact of glottal fry and sex on semitone change and CPP differences in SF0.ResultsSignificant differences were found for both sex and percent glottal fry on semitone change in SF0. A significant relationship was not found between CPP and semitone change when sex was accounted for.ConclusionsFindings from this study indicate that the measurement of SF0 for women will decline as percent of glottal fry increases. These findings have clinical implications for interpretation of SF0 measurement and evidence-based outcomes for voice therapy.