title: [Electrophysiological characterisation of envelope-following responses].
abstract: BACKGROUND
  The auditory ability to discriminate rapid changes in the envelope of language sounds is essential for speech comprehension. This ability is deteriorated in some neurological diseases such as multiple sclerosis, auditory neuropathy, sensorineural hearing loss, presbycusis and primary developmental language disorder. Envelope-following responses (EFRs) in humans are useful in objective measurement of temporal processing in the auditory nervous system.
  
  
  OBJECTIVE
  To evaluate EFRs in healthy younger subjects and to investigate the effects of subject states on the EFRs recorded.
  
  
  METHODS
  Eleven young subjects were included; six of them were awake and five were asleep. EFRs were evoked by white noise carrier stimuli with a sweep of modulation frequencies from 20 to 200Hz presented at 50dB HL.
  
  
  RESULTS
  The EFRs we recorded were similar in all subjects. There were two principal components. During both subject sleep and wakefulness, the first component (located between 30-50Hz) was significantly larger than the second component (located between 80-110Hz). There was also a significant effect of sleep on the EFR amplitude for the modulation frequencies between 88-110, 155-165 and 190-200Hz. However, there were no significant effects of sleep on the principal EFR components.
  
  
  CONCLUSIONS
  These results corroborate the usefulness of the EFR technique for objective measurement of human auditory temporal processing.
authors.affiliation: Departamento de Audición y Lenguaje, Centro de Neurociencias de Cuba, La Habana, Cuba. eleinamijares@yahoo.com
authors.forename: Eleina
authors.initials: E
authors.lastname: Mijares Nodarse
authors.forename: María Cecilia
authors.initials: MC
authors.lastname: Pérez Abalo
authors.forename: Alejandro
authors.initials: A
authors.lastname: Torres Fortuny
authors.forename: Mayrim
authors.initials: M
authors.lastname: Vega Hernández
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D004594:Electrophysiology / Q000379:methods; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D008297:Male; D012016:Reference Values; D012890:Sleep / Q000502:physiology*; D013998:Time Perception / Q000502:physiology; D055815:Young Adult