title: Susceptibility of linear and nonlinear otoacoustic emission components to low-dose styrene exposure.
abstract: OBJECTIVE
  To investigate potential susceptibility of active cochlear mechanisms to low-level styrene exposure by comparing TEOAEs in workers and controls.
  
  
  METHODS
  Two advanced analysis techniques were applied to detect sub-clinical changes in linear and nonlinear cochlear mechanisms of OAE generation: the wavelet transform to decompose TEOAEs into time-frequency components and extract signal-to-noise ratio and latency of each component, and the bispectrum to detect and extract nonlinear TEOAE contributions as quadratic frequency couplings (QFCs).
  
  
  METHODS
  Two cohorts of workers were examined: subjects exposed exclusively to styrene (N = 9), and subjects exposed to styrene and noise (N = 6). The control group was perfectly matched by age and sex to the exposed group.
  
  
  RESULTS
  Exposed subjects showed significantly lowered SNR in TEOAE components at mid-to-high frequencies (above 1.6 kHz) and a shift of QFC distribution towards lower frequencies than controls. No systematic differences were observed in latency.
  
  
  CONCLUSIONS
  Low-level styrene exposure may have induced a modification of cochlear functionality as concerns linear and nonlinear OAE generation mechanisms. The lack of change in latency seems to suggest that the OAE components, where generation region and latency are tightly coupled, may not have been affected by styrene and noise exposure levels considered here.
authors.affiliation: * Institute of Electronics, Computers and Telecommunication Engineering, CNR Italian National Research Council , Milan , Italy.
authors.forename: G
authors.initials: G
authors.lastname: Tognola
authors.forename: E
authors.initials: E
authors.lastname: Chiaramello
authors.forename: R
authors.initials: R
authors.lastname: Sisto
authors.forename: A
authors.initials: A
authors.lastname: Moleti
mesh_terms: D000328:Adult; D003051:Cochlea / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D066192:Manufacturing Industry; D016555:Matched-Pair Analysis; D008875:Middle Aged; D009623:Noise, Occupational / Q000009:adverse effects*; D016273:Occupational Exposure / Q000009:adverse effects*; D017084:Otoacoustic Emissions, Spontaneous / Q000187:drug effects* / Q000502:physiology; D059629:Signal-To-Noise Ratio; D020058:Styrene / Q000633:toxicity*
chemical_list: D020058:Styrene
keywords: Styrene exposure; cochlear active mechanisms; ototoxic effects; time-frequency distribution; non-linearity; transient evoked otoacoustic emissions