title: Formant Frequencies and Bandwidths in Relation to Clinical Variables in an Obstructive Sleep Apnea Population.
abstract: OBJECTIVE
  We investigated whether differences in formants and their bandwidths, previously reported comparing small sample population of healthy individuals and patients with obstructive sleep apnea (OSA), are detected on a larger population representative of a clinical practice scenario. We examine possible indirect or mediated effects of clinical variables, which may shed some light on the connection between speech and OSA.
  
  
  METHODS
  In a retrospective study, 241 male subjects suspected to suffer from OSA were examined. The apnea-hypopnea index (AHI) was obtained for every subject using overnight polysomnography. Furthermore, the clinical variables usually reported as predictors of OSA, body mass index (BMI), cervical perimeter, height, weight, and age, were collected. Voice samples of sustained phonations of the vowels /a/, /e/, /i/, /o/, and /u/ were recorded.
  
  
  METHODS
  Formant frequencies F1, F2, and F3 and bandwidths BW1, BW2, and BW3 of the sustained vowels were determined using spectrographic analysis. Correlations among AHI, clinical parameters, and formants and bandwidths were determined.
  
  
  RESULTS
  Correlations between AHI and clinical variables were stronger than those between AHI and voice features. AHI only correlates poorly with BW2 of /a/ and BW3 of /e/. A number of further weak but significant correlations have been detected between voice and clinical variables. Most of them were for height and age, with two higher values for age and F2 of /o/ and F2 of /u/. Only few very weak correlations were detected between voice and BMI, weight and cervical perimeter, wich are the clinical variables more correlated with AHI.
  
  
  CONCLUSIONS
  No significant correlations were detected between AHI and formant frequencies and bandwidths. Correlations between voice and other clinical factors characterizing OSA are weak but highlight the importance of considering indirect or mediated effects of such clinical variables in any research on speech and OSA.
authors: Signal, Systems and Radiocommunications Department, Universidad Politécnica de Madrid, Madrid, Spain. Electronic address: ana.montero@gaps.ssr.upm.es.
authors: Ana
authors: A
authors: Montero Benavides
authors: Signal, Systems and Radiocommunications Department, Universidad Politécnica de Madrid, Madrid, Spain.
authors: José Luis
authors: JL
authors: Blanco Murillo
authors: Signal, Systems and Radiocommunications Department, Universidad Politécnica de Madrid, Madrid, Spain.
authors: Rubén
authors: R
authors: Fernández Pozo
authors: Signal, Systems and Radiocommunications Department, Universidad Politécnica de Madrid, Madrid, Spain.
authors: Fernando
authors: F
authors: Espinoza Cuadros
authors: ATVS Biometric Recognition Group, Universidad Autónoma de Madrid, Madrid, Spain.
authors: Doroteo
authors: D
authors: Torre Toledano
authors: Hospital Quirón, Málaga, Spain.
authors: José D
authors: JD
authors: Alcázar-Ramírez
authors: Signal, Systems and Radiocommunications Department, Universidad Politécnica de Madrid, Madrid, Spain.
authors: Luis A
authors: LA
authors: Hernández Gómez
mesh_terms: D000162:Acoustics; D000328:Adult; D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D010699:Phonation; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000503:physiopathology; D013018:Sound Spectrography; D013061:Speech Acoustics; D013068:Speech Production Measurement; D014833:Voice Quality; D055815:Young Adult
keywords: Bandwidth; Clinical variables; Formant; Obstructive sleep apnea