title: Measurements of earplug attenuation under supra-aural and circumaural headphones.
abstract: OBJECTIVE
  Supra-aural audiometric headphones are generally not recommended for use in measuring the attenuation of earplugs, because contact between the headphone and pinna and/or earplug could alter the attenuation obtained, and because of concerns of non-comparability between modes of excitation from supra-aural headphones and the sound-field procedure required by the standardized method. In this study, we compared measurements of earplug attenuation obtained under Telephonics TDH-50P supra-aural headphones with measurements obtained under circumaural headphones designed expressly for such testing.
  
  
  METHODS
  The attenuation of three types of earplugs (foam, premolded quadruple-flange, and custom-molded) was measured in a repeated-measures design.
  
  
  METHODS
  The study sample comprised 42 normal-hearing adults (21 females, 21 males).
  
  
  RESULTS
  With the foam earplugs, nearly all of the attenuation measurements under the supra-aural headphones fell within 10 dB of the measurements under the circumaural headphones. With the flange and custom earplugs, approximately 10% of individuals obtained spuriously high attenuation under the supra-aural headphones.
  
  
  CONCLUSIONS
  We conclude that standard supra-aural audiometric headphones are suitable for measuring the attenuation provided by foam earplugs. However, supra-aural headphones should not be used to measure the attenuation of flange or custom-molded earplugs. The potential exists for substantial over-estimation of attenuation, especially of custom plugs.
authors.affiliation: Department of Communication Sciences, University of Connecticut, Storrs, CT 06269-1085, USA. jennifer.tufts@uconn.edu
authors.forename: Jennifer B
authors.initials: JB
authors.lastname: Tufts
authors.forename: Jillian V
authors.initials: JV
authors.lastname: Palmer
authors.forename: Lynne
authors.initials: L
authors.lastname: Marshall
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D004430:Ear Protective Devices / Q000592:standards*; D005260:Female; D006801:Humans; D008297:Male; D055815:Young Adult