title: Ear and electrode effects reduce within-group variability in middle latency response amplitude measures.
abstract: OBJECTIVE
  To establish normative amplitude values for relative difference measurements of the middle latency response (MLR) in normal-hearing pediatrics and to determine if these measurements provided a significant reduction of within-group variability when compared to raw, absolute amplitude measures. A relative amplitude difference is defined in the present paper as the difference in Na-Pa amplitude between two electrodes (e.g. |Na-Pa at C3 minus Na-Pa at C4|, or electrode effects) or between two ears (e.g. |Na-Pa on left ear stimulation minus Na-Pa on right ear stimulation|, or ear effects). In contrast, an absolute amplitude is defined as a single Na-Pa measurement made at one electrode for stimulation of one ear (e.g. Na-Pa measured at C3 on left ear stimulation).
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  155 pediatrics with normal peripheral and central hearing, and no history of psychological, neurological, or learning disability issues.
  
  
  RESULTS
  Within-group variability was significantly smaller for relative differences when compared to absolute amplitude measures. Electrode effects showed significantly less variability than ear effects. Normative values for ear and electrode effects were reported.
  
  
  CONCLUSIONS
  Relative differences may provide better utility in the clinical diagnosis of central auditory pathology in pediatrics when compared to absolute amplitude measures because these difference measures show significantly lower variability when examined across subjects.
authors.affiliation: Department of Surgery, Division of Communicative Disorders, University of Louisville, Louisville, Kentucky 40202, USA. jaweih02@louisville.edu
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Weihing
authors.forename: Eliane
authors.initials: E
authors.lastname: Schochat
authors.forename: Frank
authors.initials: F
authors.lastname: Musiek
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002648:Child; D004423:Ear / Q000502:physiology; D004566:Electrodes; D005072:Evoked Potentials, Auditory; D006801:Humans; D012016:Reference Values