title: Fitting and verification of frequency modulation systems on children with normal hearing.
abstract: BACKGROUND
  Several recent investigations support the use of frequency modulation (FM) systems in children with normal hearing and auditory processing or listening disorders such as those diagnosed with auditory processing disorders, autism spectrum disorders, attention-deficit hyperactivity disorder, Friedreich ataxia, and dyslexia. The American Academy of Audiology (AAA) published suggested procedures, but these guidelines do not cite research evidence to support the validity of the recommended procedures for fitting and verifying nonoccluding open-ear FM systems on children with normal hearing. Documenting the validity of these fitting procedures is critical to maximize the potential FM-system benefit in the above-mentioned populations of children with normal hearing and those with auditory-listening problems.
  
  
  OBJECTIVE
  The primary goal of this investigation was to determine the validity of the AAA real-ear approach to fitting FM systems on children with normal hearing. The secondary goal of this study was to examine speech-recognition performance in noise and loudness ratings without and with FM systems in children with normal hearing sensitivity.
  
  
  METHODS
  A two-group, cross-sectional design was used in the present study.
  
  
  METHODS
  Twenty-six typically functioning children, ages 5-12 yr, with normal hearing sensitivity participated in the study.
  
  
  METHODS
  Participants used a nonoccluding open-ear FM receiver during laboratory-based testing.
  
  
  METHODS
  Participants completed three laboratory tests: (1) real-ear measures, (2) speech recognition performance in noise, and (3) loudness ratings. Four real-ear measures were conducted to (1) verify that measured output met prescribed-gain targets across the 1000-4000 Hz frequency range for speech stimuli, (2) confirm that the FM-receiver volume did not exceed predicted uncomfortable loudness levels, and (3 and 4) measure changes to the real-ear unaided response when placing the FM receiver in the child's ear. After completion of the fitting, speech recognition in noise at a -5 signal-to-noise ratio and loudness ratings at a +5 signal-to-noise ratio were measured in four conditions: (1) no FM system, (2) FM receiver on the right ear, (3) FM receiver on the left ear, and (4) bilateral FM system.
  
  
  RESULTS
  The results of this study suggested that the slightly modified AAA real-ear measurement procedures resulted in a valid fitting of one FM system on children with normal hearing. On average, prescriptive targets were met for 1000, 2000, 3000, and 4000 Hz within 3 dB, and maximum output of the FM system never exceeded and was significantly lower than predicted uncomfortable loudness levels for the children. There was a minimal change in the real-ear unaided response when the open-ear FM receiver was placed into the ear. Use of the FM system on one or both ears resulted in significantly better speech recognition in noise relative to a no-FM condition, and the unilateral and bilateral FM receivers resulted in a comfortably loud signal when listening in background noise.
  
  
  CONCLUSIONS
  Real-ear measures are critical for obtaining an appropriate fit of an FM system on children with normal hearing.
authors.affiliation: Department of Speech and Hearing Sciences, University of North Texas, Denton, TX.
authors.forename: Erin C
authors.initials: EC
authors.lastname: Schafer
authors.affiliation: Department of Speech and Hearing Sciences, University of North Texas, Denton, TX.
authors.forename: Danielle
authors.initials: D
authors.lastname: Bryant
authors.affiliation: Department of Speech and Hearing Sciences, University of North Texas, Denton, TX.
authors.forename: Katie
authors.initials: K
authors.lastname: Sanders
authors.affiliation: Department of Speech and Hearing Sciences, University of North Texas, Denton, TX.
authors.forename: Nicole
authors.initials: N
authors.lastname: Baldus
authors.affiliation: Department of Speech and Hearing Sciences, University of North Texas, Denton, TX.
authors.forename: Katherine
authors.initials: K
authors.lastname: Algier
authors.affiliation: Department of Speech and Hearing Sciences, University of North Texas, Denton, TX.
authors.forename: Audrey
authors.initials: A
authors.lastname: Lewis
authors.affiliation: Department of Speech and Hearing Sciences, University of North Texas, Denton, TX.
authors.forename: Jordan
authors.initials: J
authors.lastname: Traber
authors.affiliation: Department of Speech and Hearing Sciences, University of North Texas, Denton, TX.
authors.forename: Paige
authors.initials: P
authors.lastname: Layden
authors.affiliation: Department of Speech and Hearing Sciences, University of North Texas, Denton, TX.
authors.forename: Aneeqa
authors.initials: A
authors.lastname: Amin
mesh_terms: D001308:Auditory Perceptual Disorders / Q000175:diagnosis*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006309:Hearing / Q000502:physiology*; D006801:Humans; D008297:Male; D059629:Signal-To-Noise Ratio; D013067:Speech Perception / Q000502:physiology*