The Use of FM Technology for Infants andYoung Children

Sandra Abbott Gabbard

Introduction

The successful trend of identifying hearing loss inthe first few weeks of life has resulted in many newchallenges for audiologists. For the approximately 2of every 1000 infants born who are identified withbilateral hearing loss (Mehl and Thomson, 1998), theuse of amplification is commonly the first step in theintervention process for the family. The use of hear-ing aids, combined with early intervention, has beenshown to significantly improve the speech and lan-guage skills of young children with hearing loss(Yoshinaga-Itano, 2000). Therefore the goal of ampli-fying infants with congenital hearing loss optimallybegins immediately after identification. The processincludes selection, fitting, verification and validationfor a population with its own unique issues andneeds.

Audiologists working with young infants play animport role in the lives of families including informa-tion sharing, counseling, and case management. It isimportant that parents understand the relationshipbetween hearing and communication. The goal ofamplification for infants focuses around the emergingdevelopment of language, speech perception andspeech production. Reaching decisions about theamplification for an infant includes examining avail-able technology features with the parents andempowering them with the knowledge to choose thebest option for their child given all of the availableinformation and circumstances. Technology choicesinclude the use of an FM system with the personalhearing aids with the goal of optimizing residualhearing in less than optimal environments and listen-ing contexts.

Address correspondence to: Sandra Abbott Gabbard, Ph.D., Uni-versity of Colorado, Health Services, 4200 E. 9th Ave, Box B210,Denver, CO 80262, USA.

Information for Parents FollowingEarly Diagnosis

There is compelling evidence that children bornwith hearing loss who have been identified and begunintervention by 6 months of age will have signifi-cantly better language development than their lateidentified peers (Downs and Yoshinaga-Itano, 1999;Yoshinaga-Itano et al., 1998). Recent advances inaudiologic assessment technology gives audiologiststhe opportunity to focus on the results of electro-physiologic tests including click and frequency spe-cific auditory brainstem response (ABR), AuditorySteady State Responses (ASSR), otoacoustic emis-sions (OAEs), and acoustic immittance measures(Gabbard et al. 1998). There is consensus that thediagnosis of congenital hearing loss should be com-pleted in the first three months of life and should befollowed immediately with the consideration of ampli-fication use (Joint Commission on Infant Hearing,2000).

Issues with this population often arise which maychallenge the transition from identification to earlyamplification and intervention. These include younginfants limited behavioral response to sound, thepotential for complicating middle ear fluid, parentaluncertainties, possible existence of additional handi-caps, and often limited resources to support and payfor technology. In spite of these potential hurdles, theinitiation of early intervention should not be delayed.The audiologist’s role in providing information to thefamily is a continuous one; however the quality of theinformation given to parents in the first few weeks ofthe diagnosis can effect their ability to make informedchoices about the intervention the child receives. Theparents need to be given information about theimportance of ongoing early intervention and need to

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be connected to a system. This is also an optimal timeto establish parent-to-parent support for families andto connect them to resource and funding information.

The first step in the intervention process is oftenexploring the amplification options. It is the role ofthe pediatric audiologist to share information abouthearing loss and available technology with the par-ents as well as their medical and support team. Withthe expansive growth in amplification technology inthe past few years, audiologists face constant chal-lenges in keeping up-to-date with the available tech-nology and the research to support specific strategiesin signal processing. Parents should receive informa-tion about available hearing aid types, styles, process-ing strategies, and features so they can play an activerole in the technology selection.

The possible use of FM technology with theinfant’s personal hearing aids should be included inthe comprehensive discussion of amplificationoptions. Families of infants who are only a few weeksof age should be encouraged to consider the current orfuture addition of FM to supplement the benefits ofthe hearing aids. This accessibility will be especiallyimportant when the child becomes older and mobile.FM compatibility of the hearing aids should be dis-cussed as a consideration that may influence thefamily’s hearing aid choice. For example, a family’sinterest in using FM technology may lead to a deci-sion to select hearing aids that are compatible withdirect audio input and/or a multi-memory option thatcan incorporate a hearing aid/FM setting. These earlychoices made regarding the selection of hearing aidshave consequences for the child for years to comewhile they are using the selected hearing aids.

Benefits of FM

As amplification choices are being explored forinfants, it is important to remember that it has beendemonstrated that children with all degrees of hear-ing loss often require a signal-to-noise ratio (SNR)advantage to preserve optimal speech perception innoise (Killion, 1997; Finitzo-Hieber and Tillman 1978;Gengel 1971; Ross and Giolas 1971; Crandell 1993).In order to obtain a consistent SNR ratio advantage,assistive listening technology may be necessary. Thesignal from a remote microphone can be sent directlyinto the ear of a listener by using FM system technol-ogy and a variety of transmitters and receivers. Thisdirect transmission from a remote microphone has

been widely studied and is commonly used in a class-room situation to reduce the interference between achild and the teacher (Johnson et al., 1997; Crandell& Smaldino, 2000). FM is used in educational set-tings for children with and without hearing loss as aneffective strategy to improve the listening environ-ment and reduce the problems associated withspeaker-to-listener distance, poor SNR, and roomreverberation (Crandell, 1993).

Like older children, infants and toddlers facechallenges of poor acoustic environmental conditions.Young children however are unique in their depend-ence on good speech perception abilities for the devel-opment of auditory skills and speech and languageacquisition. The use of FM technology is not com-monly used with this population and there are veryfew studies that examine this application. Benoit(1989) investigated home use of FM with toddlers.The FM systems used in this evaluation were bodyworn which challenged the acceptance of the technol-ogy by several families. Six of ten families adjustedwell to the technology. The parents reported that theFM transmitter microphone had a benefit ofencouraging their children to imitate their parent’sspeech and also resulted in parents talking more totheir children.

Moeller and her colleagues (1996) used formallanguage measures to compare two groups of two tofour year old children. One group was encouraged touse FM as much as possible at home and the othergroup used hearing aids alone. While the languagemeasures did not result in significant differencesbetween the groups, some subjects had increasedrates of language acquisition that suggested theyreceived benefit from the use of FM. The authorsreported several technology challenges includinginterference with single-channel transmitters andbody worn receivers with multiple components. Par-ents in this study did report that FM usage in noisysituation was beneficial.

Implementing FM Use

While the information about FM systems mayaffect the hearing aid choices made, it may be severalmonths before the family is ready to implement aplan for the addition of FM to the child’s listeningoptions. As infants become toddlers, the distancebetween their ear and the mouth of their parent orcaretaker begins to increase which may compromise

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audibility. Much of a young infant’s awake and listen-ing time is spent in close proximity to their parent.When the child begins to spend more and more timeseveral feet away from their parent, often not attend-ing directly to the parent’s language model, it isappropriate to consider adding the use of FM. Dis-tance however is only one issue that may influence afamily’s decision to choose FM. Others include thedegree of the childs hearing loss, the amount of com-peting background noise in the child’s environment,the child’s ability to tolerate the full time use of hear-ing aids, and the parents willingness and ability tomanage the technology.

The use of FM with young children may be bene-ficial to improve audibility for children with severe-profound hearing loss (Madell, 1992, Moeller et al,1996). The use of FM can increase the input intensityto the hearing instrument from the remote micro-phone, increasing audibility of that signal. Bothpersonal hearing aids and FM systems can benefitchildren with all degrees of hearing loss, however thefunctional benefits are often most obvious with moresignificant losses.

Parent training and support are integral com-ponents to the implementation of FM use. The par-ent’s willingness to handle the devices is a criticalvariable in the success with the instruments. Demon-stration and practice with devices in the clinical set-ting will increase the parent’s comfort in utilizing thetechnology. The use of ear level receivers minimizesthe number of components needed. Body worn unitshave been traditionally used with young children;however, completely at-the-ear components are uni-versally preferred by parents interested in FM sys-tems through the Colorado FM loaner bank. It isimportant to train the parents to perform regular lis-tening checks of the hearing aid alone and when con-nected to the FM system. Parents usually welcomethe use of a family friendly hearing aid stethoscopethat can be used for regular listening checks of theequipment.

It may be helpful to the parents to add the use ofFM technology after they have mastered the care anduse of the personal hearing aids. Many parents areoverwhelmed with the unexpected demands of hear-ing use and often are better prepared to accept andappreciate the challenges and benefits of FM technol-ogy when the child is a few months of age and is read-ily accepting the use of the hearing aids. Additionally,it may be useful to create a list of possible environ-mental applications for the FM. A discussion of the

family’s life style may result in a list which includesuse in stores, museums, parks and while the child isin a car seat, stroller, backpack, bike seat and justrunning around. The list should only be used as ageneral guideline as parents often add to or modifythe list over time.

Very young children are dependent on a variety oflistening environments for exposure to opportunitiesfor communication and language modeling. They arenot only dependent on the quality one-on-one timethat often occurs with their parents, but they are alsodependent on exposure to incidental listening thatcomes from their environment. Their own speech, aswell as speech and environmental sounds in theirenvironment, needs to be audible for the emergence ofauditory skills, speech and oral language. For thesereasons, it is important that amplified speech fromthe FM transmitter have the same high quality pro-cessing as amplified speech from the hearing aidmicrophone. This consistency in sound quality isimportant as infants attach meaning to environ-mental sounds and speech. Using an FM receiver thatis either built into the hearing aid or attached to thehearing aid will allow for this consistency. In add-ition, the hearing aid and FM microphone shouldboth be sending audible signals to the child’s earwhenever possible. For this to occur, the hearing aidused by the child needs to allow for simultaneoushearing aid and FM input.

Assessing FM Function and Benefit

The FM systems used with young children arecommonly connected directly to their personal hear-ing aids. All hearing aids should be optimallyadjusted to meet targets using a prescriptive methoddesigned to measure or estimate the audibility ofamplified speech. Both the Desired Sensation Method(Seewald et al, 1999) and the NAL-NL1 (Byrne et al.,2001) procedures have methods that can be applied toevaluate audibility. It can be valuable to evaluate thehearing aids while the FM is activated to validatethat the input from the transmitter meets the pre-scribed targets. It may be helpful to also assess theincreased audibility from the FM transmitter.

Performing informal functional listening checkswith the child in HA only and HA/FM settings in anoisy environment is a valuable way to demonstratebenefit for the child. Often the demonstration willreveal an obvious improvement in the parent’s ability

The Use of FM Technology for Infants and Young Children a 95

to get their child’s attention and in the child’s abilityto attend to the parent’s speech. This FM advantagecan also be demonstrated in the sound room using aspeech-in-noise stimulus, however until the child isable to perform a speech perception task, it may bedifficult to quantify this improvement.

The FM Listening Evaluation for Children(Appendix A) was created by Cheryl Johnson as a toolto evaluate use and benefit of hearing aids and FMsystems for young children. This questionnaireincludes a scoring system and an opportunity forsituational analysis. Each listening situation requiresa subjective score based on the child’s response. It canbe completed by a parent or professional workingwith the child. This tool can be used to assess counsel-ing and technical support needs of the family, as wellas provide outcome measures of FM benefit.

The Colorado Loaner FM Project

Colorado has had a loaner FM bank administeredby the University of Colorado Hospital since 1998.The need was first identified by parents who werevery interested is accessing the technology but hadbeen recently challenged to find the resources to sup-port their child’s personal hearing aids. The lack ofdocumented benefit of FM use with infants oftenmakes it nearly impossible to persuade third partyfunding sources to pay for the technology. The firstgeneration receivers in the bank included a mix ofear-level and body worn devices. Currently all loanersystems include two ear level receivers and onetransmitter. Some preliminary information collectedfrom parents and interventionists of young childrenparticipating in this program is presented below.

Parent and Professional Perspectivesof Early FM Use

The use of the FM Listening Evaluation forChildren (Appendix A) is routinely used in the Colo-rado Loaner FM Program as a tool to better under-stand the use and benefit from the hearing aids andFM system used by the child. Both parents and earlyintervention providers are asked to return the ques-tionnaires following at least 3–6 months of FM useand then quarterly thereafter. The results are pri-marily used to counsel and give technical assistanceand training when appropriate for families and pro-

viders. The initial survey results from nine infantsand toddlers are presented in tables 1 and 2.

The subjects included nine children between theages of 15 and 30 months of age. Hearing aid and FMsystems were all judged as easy to operate, remainedin goods working order and were comfortable for chil-dren to wear. The perceived benefit in listeningperformance between the hearing aids and the FMsystems were identical. The greatest benefits fromthe FM systems were described in the parent’s com-ments. They reported the benefits of FM systemsincluded, “being moble while continuing to hear”,“consistent sound whether noisy or not”, provides thebest amplification to help auditory skills”, “gives extraboost to hearing aids”, “keeps him focused on thespeaker”, and “improves attention in noise”.

Discussion

The choice of using an FM system for a youngchild clearly requires family commitment and sup-portive professionals. In the past, FM use has beenlimited to school children who have had to access theFM signal separate from their personal hearing aids.

Table 1. Description of participants

Number 9Age range 15–30 monthsAverage age of confirmed HL 3 monthsAverage age of HA fitting 4.5 monthsAverage age intervention start 6 monthsAverage age of FM fitting 17 monthsDegree of hearing loss mild-profoundHA use in hours/day 10 (range 4–12)FM use in hours/day 4 (range 2–12)FM technology 6 ear level, 3 body

worn

Table 2. Results of FM Listening Evaluation for Children(scores based on 1-seldom, 3-sometimes, 5-usually)

HA FM

Technology easy to operate 4.0 3.88Technology remained in good working

order4.0 5.0

Technology judged as comfortable forchildren to use

4.28 4.6

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With the technology available today, ear levelreceivers allow the FM system to be coupled to thechild’s hearing aids without the use of cords and bodyworn devices. This not only facilitates a consistentsignal to the child’s ear from either the hearing aidand/or FM microphone, it also results in an easiersystem to manage from the parent’s perspective.

Our positive experiences with families accessingtechnology from the Colorado Loaner FM programhave led us to the conclusions that many families caneasily use and maintain the equipment with on-goinginformation and support. While the use of an FM sys-tem is not chosen by all families, many families valuethe contribution they have on the child’s ability tocommunicate in difficult listening situations. Clearlymore research on the benefits of FM use in youngchildren is needed, however assessing outcomes ofFM cannot be completely separated from the bene-fits of the personal hearing aids and the early inter-vention services. It is easy to value a system thathas the ability to provide an improved listeningenvironment for young children during their criticalyears of auditory skill and speech and languagedevelopment.

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Appendix 1

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