Acoustic events and "optophonic" cochlear responses induced by pulsed near-infrared LASER

Ingo Ulrik Teudt, Hannes Maier, Claus Peter Richter, Andrej Kral

Research output: Contribution to journalArticlepeer-review

74 Scopus citations

Abstract

Optical stimulation of neural tissue within the cochlea was described as a possible alternative to electrical stimulation. Most optical stimulation was performed with pulsed lasers operating with near-infrared (NIR) light and in thermal confinement. Under these conditions, the coexistence of laser-induced optoacoustic stimulation of the cochlea ("optophony") has not been analyzed yet. This study demonstrates that pulsed 1850-nm laser light used for neural stimulation also results in sound pressure levels up to 62dB peak-to-peak equivalent sound pressure level (SPL) in air. The sound field was confined to a small volume along the laser beam. In dry nitrogen, laser-induced acoustic events disappeared. Hydrophone measurements demonstrated pressure waves for laser fibers immersed in water. In hearing rats, laser-evoked signals were recorded from the cochlea without targeting neural tissue. The signals showed a two-domain response differing in amplitude and latency functions, as well as sensitivity to white-noise masking. The first component had characteristics of a cochlear microphonic potential, and the second component was characteristic for a compound action potential. The present data demonstrate that laser-evoked acoustic events can stimulate a hearing cochlea. Whenever optical stimulation is used, care must be taken to distinguish between such "optophony" and the true optoneural response.

Original languageEnglish (US)
Article number5701771
Pages (from-to)1648-1655
Number of pages8
JournalIEEE Transactions on Biomedical Engineering
Volume58
Issue number6
DOIs
StatePublished - Jun 2011

Keywords

  • Auditory system
  • hearing aids
  • infrared-radiation effects
  • optical-radiation effects
  • photoacoustic effects

ASJC Scopus subject areas

  • Biomedical Engineering

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