title: The effect of angulation of the vibrating floating mass transducer on stapes velocity.
abstract: OBJECTIVE
  Changes to the angular position of the vibrating floating mass transducer (FMT) coupled to the long process of the incus will not affect stapes velocity.
  
  
  OBJECTIVE
  The MED-EL Vibrant Soundbridge is an active middle ear implantable device, which constitutes an effective alternative to acoustic hearing aids for the rehabilitation of patients with sensorineural and mixed hearing loss. Because of varied anatomy, it is not always possible to position the FMT in line with the vibrating axis of the stapes. Changes in stapes velocity after angulation of the FMT are measured using laser Doppler vibrometry (LDV).
  
  
  METHODS
  The study was performed on 7 human cadaveric temporal bones. The FMT was attached to the incus and angled at the recommended 0 degree or at 45 degrees relative to the vibrating axis of the stapes, and the stapes velocity measured using LDV.
  
  
  RESULTS
  In comparison to the 0-degree position, angulating the FMT to 45 degrees reduced cochlea input as measured by stapes velocity, although there was no statistical significance to this difference. Placing the FMT at 45 degrees did not compromise the peak output of the device but resulted in a phase lag which was more marked compared with the 0-degree position.
  
  
  CONCLUSIONS
  If it is not anatomically possible to position the FMT in line with the vibrating axis of the stapes, then placement at up to 45 degrees does not significantly alter the performance of the implant particularly in the midfrequencies that are crucial to the understanding of speech.
authors.affiliation: *Department of Otolaryngology, Guy's and St. Thomas' Hospital, London; and †Centre for Biomimetics, School of Construction Management and Engineering, University of Reading, UK.
authors.forename: Nwaneka
authors.initials: N
authors.lastname: Eze
authors.forename: Antonio
authors.initials: A
authors.lastname: Mirón
authors.forename: Genevieve
authors.initials: G
authors.lastname: Rogers
authors.forename: George
authors.initials: G
authors.lastname: Jeronimidis
authors.forename: Alec Fitzgerald
authors.initials: AF
authors.lastname: O'Connor
authors.forename: Dan
authors.initials: D
authors.lastname: Jiang
mesh_terms: D006801:Humans; D007188:Incus / Q000502:physiology / Q000601:surgery*; D009998:Ossicular Prosthesis; D013199:Stapes / Q000502:physiology*; D013701:Temporal Bone / Q000601:surgery*; D014159:Transducers; D014732:Vibration