title: Otoacoustic emissions growth rate threshold: distortion product in neonates.
abstract: BACKGROUND
  Distortion product otoacoustic emission measures (DPOAE) verifies, among other characteristics, the emergence and growth rate of the DPOAE response according to sound stimulus intensity (growth curve).
  
  
  OBJECTIVE
  To estimate the DPOAE threshold in neonates according to the DPOAE growth curve at 2 kHz and 4 kHz, with stimulus presentation ranging between 35 and 70 dB SPL.
  
  
  METHODS
  Participants were 51 neonates, with 24 to 84 hours of life and with no indication of risk for hearing impairment. The DPOAE were registered in the growth curve function at 2 kHz and at 4 kHz. Neonates were evaluated during the period of hospital stay, after birth. Three possible thresholds were considered (LIM 1, LIM 2 and LIM 3) based on the presence of response at 3 dB SPL in the signal to noise ratio.
  
  
  RESULTS
  The average thresholds intensities ranged from 47.55 to 49.85 dB at 2 kHz and from 55.52 to 59.94 dB at 4 kHz. The mean amplitude response ranged from 6.67 to 8.27 dB at 2 kHz and from 6.99 to 11.35 dB at 4 kHz. There was significant difference between the three thresholds for the two studied frequencies.
  
  
  CONCLUSIONS
  The procedure was feasible for the neonatal population revealing mean thresholds of up to 60 dB for both frequencies. Even though participants presented elevated thresholds, robust amplitude responses were observed.
authors.affiliation: Faculdade de Medicina, Universidade de São Paulo. patriciapalmeida@gmail.com
authors.forename: Patricia Pinheiro de
authors.initials: PP
authors.lastname: Almeida
authors.forename: Seisse Gabriela Gandolfi
authors.initials: SG
authors.lastname: Sanches
authors.forename: Renata Mota Mamede
authors.initials: RM
authors.lastname: Carvallo
mesh_terms: D001309:Auditory Threshold / Q000502:physiology*; D003051:Cochlea / Q000503:physiopathology; D005072:Evoked Potentials, Auditory; D005240:Feasibility Studies; D005260:Female; D006320:Hearing Tests; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*; D010469:Perceptual Distortion / Q000502:physiology*; D012016:Reference Values; D018709:Statistics, Nonparametric