title: Perceptual-auditory and Acoustic Analysis of Air Traffic Controllers' Voices Pre- and Postshift.
abstract: OBJECTIVE
  To characterize the vocal quality and acoustic parameters of voices of air traffic controllers (ATCs) without any vocal complaints before and after a shift.
  
  
  METHODS
  The voices of a group of 45 ATCs were recorded before and after a 2-hour shift, regardless of their operational position or number of previously worked shifts; both genders were included, participants had a mean age of 25 years, and they had a mean length of occupational experience of 4 years and 2 months. Each of these professionals was recorded phonating a sustained /a/ vowel and counting from 1 to 20, and the recordings were acoustically analyzed using the Praat software. A perceptual-auditory analysis of the recordings was then performed by three speech therapists specializing in voice, who evaluated the characteristics of each emission using a visual analog scale (VAS). The acoustic analysis was performed on the sustained /a/ vowel. The measures of intensity; frequency; maximum phonation time (MPT); and the first, second, third, and fourth formants were considered in this analysis.
  
  
  RESULTS
  There were no significant differences between the random pre- and postshift samples, either in the acoustic or in the perceptual-auditory analysis. The perceptual-auditory analysis revealed that 44% (n = 20) of ATCs showed alterations in vocal quality during the sustained /a/ vowel emission, and this dysphonia was also observed in connected speech in 25% (n = 5) of this group.
  
  
  CONCLUSIONS
  Perceptual-auditory analysis of the /a/ vowel revealed that a high percentage of ATCs had vocal alterations (44%), even among a group of subjects without vocal complaints.
authors.affiliation: Speech Therapy, Federal University of Sao Paulo, Sao Paulo, Brazil.. Electronic address: carolwaack@hotmail.com.
authors.forename: Anna C N W B
authors.initials: AC
authors.lastname: Villar
authors.affiliation: Speech Therapy, Federal University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Gustavo P
authors.initials: GP
authors.lastname: Korn
authors.affiliation: Speech Therapy, Federal University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Renata R
authors.initials: RR
authors.lastname: Azevedo
mesh_terms: D000060:Accidents, Aviation / Q000517:prevention & control; D000162:Acoustics; D000328:Adult; D001359:Aviation; D005260:Female; D006801:Humans; D007600:Judgment; D008297:Male; D009784:Occupational Diseases / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology / Q000523:psychology; D016272:Occupational Health; D009790:Occupations; D010699:Phonation; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012307:Risk Factors; D013018:Sound Spectrography; D013067:Speech Perception; D013068:Speech Production Measurement; D013070:Speech Therapy / Q000379:methods*; D013997:Time Factors; D014832:Voice Disorders / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology / Q000523:psychology; D014833:Voice Quality; D055815:Young Adult
keywords: Acoustic; Dysphonia; Perceptual-auditory; Voice; Voice disorders