Optimizing FM Systems: Verification of Device Function at Fitting and Follow-Up Preserves Advantages of Use Many clinicians are familiar with the use of FM systems (incorporating a transmitter microphone used by the speaker and a receiver used by the listener) for children and adults. Studies indicate FM systems are effective for peripheral hearing loss, central processing deficits, and learning disabilities, as well as for facilitating ... Features
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Features  |   October 01, 2011
Optimizing FM Systems: Verification of Device Function at Fitting and Follow-Up Preserves Advantages of Use
Author Notes
  • Huong Nguyen, PhD, recently completed her doctoral degree in the Department of Communication Sciences and Disorders at the University of Iowa. Contact her at hananey767@gmail.com.
    Huong Nguyen, PhD, recently completed her doctoral degree in the Department of Communication Sciences and Disorders at the University of Iowa. Contact her at hananey767@gmail.com.×
  • Ruth Bentler, PhD, CCC-A, is professor and chair in the Department of Communication Sciences and Disorders at the University of Iowa. She teaches and conducts research in the area of amplification. Contact her at ruth-bentler@uiowa.edu.
    Ruth Bentler, PhD, CCC-A, is professor and chair in the Department of Communication Sciences and Disorders at the University of Iowa. She teaches and conducts research in the area of amplification. Contact her at ruth-bentler@uiowa.edu.×
Article Information
Hearing Aids, Cochlear Implants & Assistive Technology / Features
Features   |   October 01, 2011
Optimizing FM Systems: Verification of Device Function at Fitting and Follow-Up Preserves Advantages of Use
The ASHA Leader, October 2011, Vol. 16, 5-6. doi:10.1044/leader.FTR6.16122011.5
The ASHA Leader, October 2011, Vol. 16, 5-6. doi:10.1044/leader.FTR6.16122011.5
Many clinicians are familiar with the use of FM systems (incorporating a transmitter microphone used by the speaker and a receiver used by the listener) for children and adults. Studies indicate FM systems are effective for peripheral hearing loss, central processing deficits, and learning disabilities, as well as for facilitating listening in theaters, lecture halls, and places of worship. For children with hearing loss, the use of FM systems also has been shown to enhance reading skills, increase attention span, and reduce distractibility (Crandell, Smaldino, & Flexer, 1995; Flexer, Biley, Hinkley, Harkema, & Holcomb, 2002; McSporran, 1997). Current evidence shows, however, that some advantages may be lost without verification of device function at the fitting and during all follow-up visits.
Optimizing FM System Settings
One of the advantages of using an FM system is placement of the microphone very close to the speaker’s mouth, transmitting speech to the listener at a higher level than would otherwise occur. Several sets of guidelines are available to assist the clinician in optimizing the settings of the FM microphone in relation to the environmental—or hearing aid—microphone (ASHA, 1994, 2002). The 1994 guidelines are worded to provide equal output for both the FM and hearing aid (HA) microphones. That is, even though the input level to the FM microphone is typically higher than the input level to the HA microphone (for a conversation partner), the outputs generated in the ear were set at an equal level.
With input from a number of pediatric clinicians and researchers, the guidelines were rewritten in 2002 to provide an FM-advantage approach. That is, it was appropriately determined that the input to the FM microphone should provide the primary signal to the child. Consequently, the guidelines suggested a 10-dB-higher output for FM-microphone inputs.
FM Systems and Hearing Aids
Hawkins (1984) assessed the impact of HA and FM system use on children with mild to moderate sensorineural hearing loss (SNHL) in various combinations: HA-only, FM-only, FM+HA (with omnidirectional or directional FM microphones), and other combinations. The findings suggested that children’s word-recognition scores were better in FM-only mode than in HA-only and FM+HA modes. There was no significant difference between HA-only and FM+HA when the microphone of the FM system was omnidirectional.
Similarly, Boothroyd and Iglehart (1998) evaluated the efficacy of FM systems for teenagers with severe to profound hearing loss. The study revealed that subjects’ phoneme correction was higher in FM-system use than HA use in both quiet and noisy listening environments. More recently, Anderson and Goldstein (2004) assessed the impact of FM systems (e.g., infrared system, desktop personal soundfield system, and FM systems linked to personal hearing aids) on kindergarten children with hearing loss. The results revealed no difference between HA-only and infrared systems. However, the children’s speech perception in noise increased when desktop and personal FM systems were connected with their hearing aids.
Verifying Microphone Function
We recently conducted a single-subject design study to assess FM effectiveness under various controlled conditions (Experiment 1). We also were interested in how training of the parent/caregiver would affect those interactions (Experiment 2). Experiment 1 consisted of four listening conditions (HA+quiet, HA+noise, FM+quiet, and FM+noise). The order of implementation of the four conditions was randomized. Experiment 2 consisted of two phases (A=pre-training and B=post-training). Data for phase A were the recordings obtained from Experiment 1. Data for phase B, collected following parent/caregiver training, consisted of parent/caregiver and child interaction across the four listening conditions.
We held two sessions of data collection, each after a 15-minute training period. A training package, “It Takes Two to Talk” (Girolametto & Weitzman, 2006), was used to prepare a one-page handout of communication strategies for the parent/caregiver. During the training, the parent/caregiver and the investigator discussed strategies of interest that the parent/caregiver felt comfortable applying when interacting with the child after the training section. Following the trainings, the interaction between parent/caregiver and child was reassessed randomly across the four conditions.
Two dyads of parent/caregiver and 5-year-old child were recruited. The children had documented mild to moderate hearing loss and no previous FM experience. Interactions were assessed on three types of communicative behaviors: child’s vocalization, parent/caregiver’s response, and parent/caregiver’s initiation. The parents/caregivers were blinded to the condition.
Findings
Our findings indicated that for one subject, use of the FM system (i.e., FM-only mode) facilitated the child’s ability to maintain the same level of interaction in noisy as in quiet environments. Caregiver training also enhanced the impact of FM system use for this child. That is, the child’s vocalization was greater in HA+quiet than in HA+noise, but not different between FM+quiet and FM+noise, suggesting that use of the hearing aid in the presence of background noise reduces a child’s likelihood to communicate.
Alternately, the use of the FM system facilitated communication equally whether noise was present or not. Because an FM system can capture the intended voice, while overcoming both noise and distance factors, these data suggest that children may be more likely to practice their emerging language with FM use. Training also seemed to facilitate communication between the child and his caretaker, in that vocalization frequency increased for both in the FM+noise post-training trials.
The other child did not fare as well in the FM-only condition with background noise, with or without parent training. Follow-up examination of the amplification systems revealed a device “flaw” that was not obvious in the electroacoustic or listening evaluations. That is, the HA microphone was still active in the FM-only mode, resulting in unintentional and unwarranted noise input to the child in the FM-only condition. This input was not intended and likely resulted in the different outcomes for these children.
The usefulness of FM systems for both children and adults has been extensively studied and documented. Our recent study suggested that an FM system facilitates child communication in noisy environments better than a hearing aid (alone) is capable of doing. However, it is important to verify the function of both FM and HA microphones during fitting and follow-up for all amplification devices. Otherwise, FM advantage(s) might be lost, resulting in diminished perceptual/language-learning opportunities for these children.
Sources
Anderson, K. L., & Goldstein, H. (2004). Speech perception benefits of FM and infrared devices to children with hearing aids in a typical classroom. Language, Speech, and Hearing Services in Schools, 35, 169–184. [Article] [PubMed]
Anderson, K. L., & Goldstein, H. (2004). Speech perception benefits of FM and infrared devices to children with hearing aids in a typical classroom. Language, Speech, and Hearing Services in Schools, 35, 169–184. [Article] [PubMed]×
American Speech-Language-Hearing Association (1994). Guidelines for fitting and monitoring FM systems. ASHA 36 (Supplement 12), 1–9. [PubMed]
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American Speech-Language-Hearing Association (2002). Guidelines for fitting and monitoring FM systems. Available from www.asha.org/policy.
American Speech-Language-Hearing Association (2002). Guidelines for fitting and monitoring FM systems. Available from www.asha.org/policy.×
Boothroyd, A., & Iglehart, F. (1998). Experiments with classroom FM amplification. Ear and Hearing, 19(3), 202–217. [Article] [PubMed]
Boothroyd, A., & Iglehart, F. (1998). Experiments with classroom FM amplification. Ear and Hearing, 19(3), 202–217. [Article] [PubMed]×
Crandell, C., Smaldino, J., & Flexer, C. (1995). Sound-field FM amplification: Theory and practical applications. San Diego, CA: Singular.
Crandell, C., Smaldino, J., & Flexer, C. (1995). Sound-field FM amplification: Theory and practical applications. San Diego, CA: Singular.×
DiSarno, N., & Schowalter, M. (2002). Classroom amplification to enhance student performance. Teaching Exceptional Children, 34(6), 20–26.
DiSarno, N., & Schowalter, M. (2002). Classroom amplification to enhance student performance. Teaching Exceptional Children, 34(6), 20–26.×
Flexer, C., Biley, K. K., Hinkley, A., Harkema, C., & Holcomb, J. (2002). Using sound-field systems to teach phonemic awareness to pre-schoolers, The Hearing Journal, 55(3).
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Girolametto, L., & Weitzman, E. (2006). It takes two to talk. The Hanen program for parents: Early language intervention through caregiver training. In McCauley, R. and Fey, M. (Eds.), Treatment of language disorders in children (pp. 77–103). Baltimore, MD: Paul H. Brookes.
Girolametto, L., & Weitzman, E. (2006). It takes two to talk. The Hanen program for parents: Early language intervention through caregiver training. In McCauley, R. and Fey, M. (Eds.), Treatment of language disorders in children (pp. 77–103). Baltimore, MD: Paul H. Brookes.×
Hawkins, D. B. (1984).Comparisons of speech recognition in noise by mildly-to-moderately hearing-impaired children using hearing aids and FM systems. The Journal of Speech and Hearing Disorders, 49(4), 409–418.
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McSporran, E. (1997). Towards better listening and learning in the classroom. Educational Review, 49(1), 13–20. [Article]
McSporran, E. (1997). Towards better listening and learning in the classroom. Educational Review, 49(1), 13–20. [Article] ×
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