title: Contact quotient versus closed quotient: a comparative study on professional male singers.
abstract: OBJECTIVE
  The term "closed quotient" is frequently used for data derived both from inverse filtering and from electroglottography. In the former case, it is defined as the ratio between the closed phase and the period, as measured in flow glottograms (FLOGG), whereas in the latter case, it is defined as the time interval between the falling and rising parts of the electroglottogram (EGG), measured at some percentage of the peak-to-peak amplitude. The study aims at analyzing differences between EGG- and FLOGG-based closed quotients and their relationships with voice source parameters.
  
  
  METHODS
  Comparative study.
  
  
  METHODS
  FLOGG- and EGG-based measures collected from five professional male singers were compared, under different pitch and loudness conditions.
  
  
  RESULTS
  Compared with the FLOGG-based quotient, the EGG-based quotient (i) varied more between subjects, (ii) presented greater values, (iii) varied less with subglottal pressure, (iv) varied less with the normalized amplitude quotient (ie, the ratio between the flow pulse amplitude and the product of period and maximum flow declination rate), and (v) varied less with the relative amplitude of the voice source fundamental.
  
  
  CONCLUSIONS
  Although positively related, FLOGG- and EGG-based closed quotients differ and must not be confused.
authors.affiliation: University of Aveiro, Aveiro, Portugal; INET-MD, Aveiro, Portugal. Electronic address: filipasoprano@gmail.com.
authors.forename: Filipa M B
authors.initials: FM
authors.lastname: Lã
authors.affiliation: KTH, Stockholm, Sweden; University College of Music Education, Stockholm, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Sundberg
mesh_terms: D000328:Adult; D005931:Glottis / Q000502:physiology*; D006801:Humans; D008297:Male; D010699:Phonation / Q000502:physiology*; D011312:Pressure; D063346:Singing / Q000502:physiology*; D013061:Speech Acoustics; D014833:Voice Quality
keywords: Closed quotient; Contact quotient; Electrolaryngography; Flow glottogram; Inverse filtering; Trained male voices; Voice source analysis