The Widex Pediatric Rationale endeavors to simplify hearing aid fitting in children so that the correct amount of gain at all input levels can be prescribed accurately and efficiently.
Pediatric Rationale objective:
The hearing aid shall provide equal sound pressure level at the eardrum of a child
and an adult with equal hearing loss.
Highlights of the Pediatric Rationale:
The “true” hearing loss of the young child is not reflected by the audiometer dial reading.
- At the same audiometer dial reading, the SPL in a child’s ear is higher than that of an adult’s (because of a smaller ear canal volume). This difference decreases as the child ages.
- Earcanal is shorter and has a smaller volume (Figure 4)
- Earcanal resonance is at a higher frequency (Figure 5)
Thus a child under 5 years who has a hearing loss of 40 dB HL actually has a hearing loss that is more than 40 dB dial reading.
Widex has adopted the term Equivalent Adult Threshold (EAT) from NAL to report on the true hearing loss of the child. This we do by considering the age of the child as well as the transducer that was used to estimate the child’s audiometric thresholds. The EAT, like the dB HL notation, is independent of the child’s age and transducers.
Because of the smaller ear canal volume of a child (under 5 years of age), the same settings on a hearing aid will result in a higher sound pressure level in the earcanal of a child than that of an adult. Thus, infants and young children need less coupler gain on a hearing aid to achieve the desired output from hearing aids compared to older children and adults who have the same degree of hearing loss.