Ensuring well-fitted earmolds for infants and toddlers

Abstract

Universal newborn hearing screening has allowed audiologists to fit hearing aids on children during their first few weeks of life. But ensuring well-fitted amplification for newborns is challenging, especially providing well-fitted earmolds. Here are several tips on optimizing earmolds for infants: GET READY FOR A CLOSE RELATIONSHIP Infants grow quickly during their first few months. The average child's weight doubles between birth (almost 8 pounds) and 6 months (just over 17 pounds). In contrast, it takes about 3 years for a 6-month-old's weight to double again. Accompanying this rapid growth during children's first 6 months are concurrent changes in their ears. In fact, the RECD (DSL-i/o 5.0) at 3000 Hz changes more between the ages of 1 and 6 months than from 6 months to 3 years. These changes and occur in a child's external ear during the first few months of life quickly result in loose-fitting earmolds that produce acoustic feedback. With this in mind, we scratch our heads every time we read an article or hear a speaker state that young children will need 4 to 6 earmolds during their first year. In our experience, earmolds must be replaced as frequently as every few days during the child's first few months. Thus it is not uncommon for a newborn fitted during her first few weeks of life to require 15 to 20 earmolds by her first birthday. Frequent earmold re-makes are especially important for infants with severe hearing loss in the high frequencies. Harvey Dillon's work has shown that a BTE with an occluded earmold will provide, on average, 40 dB of insertion gain before feedback for an adult. Since the speech sounds at 4000 Hz frequently occur near 20-25 dB HL (/s/, /f/, /th/), a 70-dB-HL hearing loss at 4000 Hz requires at least 45 dB of gain to provide audibility for high-frequency phonemes. As Dillon has noted, providing 40 dB or more of high-frequency gain necessitates a tight-fitting earmold. Of course, feedback cancellation in contemporary hearing aids can provide as much as 15 to 20 dB of additional gain before feedback and should be considered as imperative for infants with significant hearing loss. To achieve this, new earmolds are needed at least every 2 weeks—and often every few days—during the first couple of months after fitting (a little less frequently for infants with mild hearing loss). It's essential to be proactive. A good rule of thumb is to schedule weekly hearing aid checks during a baby's few months. Ear impressions can be taken to obtain new molds, and additional time may be spent discussing hearing aid care and function with the parent. From age 3 to 6 months, hearing aid checks should take place every 2 to 4 weeks. Also, families should be taught to recognize when earmolds begin to fit loosely or when acoustic feedback starts and to call the clinic to schedule an appointment. The impressions should be taken within a day or 2 of the call, and the earmolds should be fitted within days of the impression taking. At about 6 months, ear growth usually begins to stabilize and earmolds are more likely to provide several weeks of use without feedback. RACING AGAINST THE CLOCK In fitting infants, ear impressions should be delivered to the laboratory within a day of when they are taken. Every day that elapses after the impression taking is another day the baby goes without well-fitted hearing aids and a day less that the new earmolds will fit well. Discuss with your earmold lab how to obtain same-day service for earmolds for young children. Also, try to schedule the fitting on the day the earmolds arrive. TEMPORARY SOLUTIONS The folks at Boystown have developed a clever temporary earmold for infants awaiting permanent custom molds. Wrapping a Comply strip around standard size 13 tubing creates a functional mold for a short fix. We've also had pretty good success with personally manufacturing earmolds in the clinic for children with mild to moderately severe hearing loss. Specifically, using Instamold we can fit a custom earmold on an infant in minutes. REMINDERS Soft earmold material should be used with infants. Vinyl is usually a good choice, because it is comfortably soft but not so flexible that insertion is difficult. Silicone is effective at reducing acoustic feedback, but its enhanced pliability may make insertion difficult for parents. In the end, the rewards associated with well-fitted amplification make it worth the time and energy you invest. Good luck!