title: Rinne test: does the tuning fork position affect the sound amplitude at the ear?
abstract: BACKGROUND
  Guidelines and text-book descriptions of the Rinne test advise orienting the tuning fork tines in parallel with the longitudinal axis of the external auditory canal (EAC), presumably to maximise the amplitude of the air conducted sound signal at the ear. Whether the orientation of the tuning fork tines affects the amplitude of the sound signal at the ear in clinical practice has not been previously reported. The present study had two goals: determine if (1) there is clinician variability in tuning fork placement when presenting the air-conduction stimulus during the Rinne test; (2) the orientation of the tuning fork tines, parallel versus perpendicular to the EAC, affects the sound amplitude at the ear.
  
  
  METHODS
  To assess the variability in performing the Rinne test, the Canadian Society of Otolaryngology - Head and Neck Surgery members were surveyed. The amplitudes of the sound delivered to the tympanic membrane with the activated tuning fork tines held in parallel, and perpendicular to, the longitudinal axis of the EAC were measured using a Knowles Electronics Mannequin for Acoustic Research (KEMAR) with the microphone of a sound level meter inserted in the pinna insert.
  
  
  RESULTS
  47.4 and 44.8% of 116 survey responders reported placing the fork parallel and perpendicular to the EAC respectively. The sound intensity (sound-pressure level) recorded at the tympanic membrane with the 512 Hz tuning fork tines in parallel with as opposed to perpendicular to the EAC was louder by 2.5 dB (95% CI: 1.35, 3.65 dB; p < 0.0001) for the fundamental frequency (512 Hz), and by 4.94 dB (95% CI: 3.10, 6.78 dB; p < 0.0001) and 3.70 dB (95% CI: 1.62, 5.78 dB; p = .001) for the two harmonic (non-fundamental) frequencies (1 and 3.15 kHz), respectively. The 256 Hz tuning fork in parallel with the EAC as opposed to perpendicular to was louder by 0.83 dB (95% CI: -0.26, 1.93 dB; p = 0.14) for the fundamental frequency (256 Hz), and by 4.28 dB (95% CI: 2.65, 5.90 dB; p < 0.001) and 1.93 dB (95% CI: 0.26, 3.61 dB; p = .02) for the two harmonic frequencies (500 and 4 kHz) respectively.
  
  
  CONCLUSIONS
  Clinicians vary in their orientation of the tuning fork tines in relation to the EAC when performing the Rinne test. Placement of the tuning fork tines in parallel as opposed to perpendicular to the EAC results in a higher sound amplitude at the level of the tympanic membrane.
authors.affiliation: Division of Otolaryngology - Head and Neck Surgery, Vancouver General Hospital, Vancouver, BC, Canada. butskiy.alex@gmail.com.|Department of Surgery, University of British Columbia, Vancouver, BC, Canada. butskiy.alex@gmail.com.|Gordon & Leslie Diamond Health Care Centre, 4th. Fl. 4299B-2775 Laurel Street, Vancouver, BC, V5Z 1M9, Canada. butskiy.alex@gmail.com.
authors.forename: Oleksandr
authors.initials: O
authors.lastname: Butskiy
authors.affiliation: Department of Mechanical Engineering, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Denny
authors.initials: D
authors.lastname: Ng
authors.affiliation: Department of Mechanical Engineering, University of British Columbia, Vancouver, BC, Canada.|School of Population and Public Health, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Murray
authors.initials: M
authors.lastname: Hodgson
authors.affiliation: Division of Otolaryngology - Head and Neck Surgery, Vancouver General Hospital, Vancouver, BC, Canada.|Department of Surgery, University of British Columbia, Vancouver, BC, Canada.|Gordon & Leslie Diamond Health Care Centre, 4th. Fl. 4299B-2775 Laurel Street, Vancouver, BC, V5Z 1M9, Canada.
authors.forename: Desmond A
authors.initials: DA
authors.lastname: Nunez
mesh_terms: D001844:Bone Conduction / Q000502:physiology*; D004424:Ear Canal / Q000503:physiopathology*; D004867:Equipment Design; D034381:Hearing Loss / Q000175:diagnosis* / Q000503:physiopathology; D006320:Hearing Tests / Q000295:instrumentation*; D006801:Humans; D013016:Sound; D014432:Tympanic Membrane / Q000503:physiopathology*
keywords: Physical examination; Rinne test; Tuning fork