In North Carolina, children are screened only prior to starting public school in kindergarten, although many speech-language pathologists (SLPs) commonly screen children in kindergarten and third grade. This practice differs from the guidelines issued by the American Speech-Language-Hearing Association (ASHA)1 and the American Academy of Audiology (AAA),2 both of which recommend screening multiple grades. As a result, it is hypothesized that many children with progressive, fluctuating, or acquired hearing loss may be missed. In addition, state guidelines vary with regard to recommended hearing screening procedures. In this study, consideration was given to the impact of screening criteria on the failure rate. Although it is recommended that 20 dB HL be used for detecting minimal hearing loss,1, 2, 3 25 dB HL is often used due to the level of ambient noise in schools. Some guidelines also recommend including 6,000 Hz in detecting noise-induced hearing loss in school children.4, 5, 6 Finally, a diagnostic evaluation is necessary to document the sensitivity and specificity of the hearing screening and determine follow-up compliance.7 Given the potential negative impact of hearing loss on auditory learning and communication, this study aimed to document how school hearing screening procedures impact outcomes.
A total of 1,181 children in kindergarten (K) through ninth grade were screened at a charter school during fall 2016. Two years later, 862 children (K to eighth grade) were screened in an effort to replicate these findings and collect additional data for analysis. Two audiologists, two SLPs, and numerous graduate student clinicians assisted with the screening. The hearing screening protocol is described below:
- Children were screened at 1, 2, 4, and 6 kHz at 20 dB HL with at least two stimulus presentations before a response (or no response) was recorded.
- All children who failed at least one frequency were immediately rescreened at 20 dB (and increased to 25 dB if needed) as a reliability check. Headphones were removed, the child was reinstructed, and missed frequencies were rescreened.1,2
- Failure to respond at one or more frequencies in either ear was considered a fail at 25 dB HL.
- Children were rescreened within three weeks by a clinician blind to the initial results and referred for a diagnostic evaluation if they did not pass the rescreening.
- An audiologist performed otoscopy and tympanometry on all children who failed the initial screening.2 In addition, distortion product otoacoustic emissions (DPOAEs) were measured from 1 to 6 kHz in 2018.
IRB approval was received to offer all children who failed the rescreening in 2018 a free diagnostic evaluation. Letters were sent home and follow-up phone calls were made by the SLP at the school. Although several parents said they were interested in a diagnostic evaluation, only two children were seen as part of this study (6% rate of follow-up compliance). At least nine parents reported following up elsewhere, with some reporting that they went to a pediatrician's office for screening. Thus, the actual rate of follow-up compliance is likely higher, albeit still poor and inadequate for diagnosis.
The study found that a similar number of children failed the pure tone screening in 2016 and 2018, suggesting that the results are replicable. In 2016, 107 children (9% of total) failed the initial pure tone screening, and 38 children failed the rescreening, resulting in a three percent failure rate. In 2018, 96 children (11% of total) failed the initial screening, and 31 children failed the rescreening, resulting in a four percent failure rate.
As shown in Figure 1, the children who failed the rescreening were distributed across grades, with the most failures in third grade in 2016 and fifth grade in 2018. This finding was not surprising given that the two samples overlapped and comprised the same children tested two years apart.
Figure 2 compares the number of referrals that would be missed using the following guidelines: North Carolina requirements, SLP Practice, ASHA, and AAA. Notably, as few as one in 12 children (8%) who failed the screening would have been referred for a diagnostic hearing test if only K is screened. Although more children are captured using the other guidelines, 39 percent of referrals (n = 12) would still be missed at best (using the AAA guidelines).
Findings of otoscopy and tympanometry were abnormal in four percent of children screened in 2016 (n = 27) and in three percent of children screened in 2018 (n = 23). Of the 10 students who passed the pure tone rescreening at 25 dB (2018), all were referred for medical intervention based on the outer/middle ear screening (e.g., occluding wax, flat/negative tympanograms). At the rescreening, 40 percent of children had absent DPOAE responses. Of these, seven had absent DPOAEs, with normal outer/middle ear function supporting the need for diagnostic testing. Notably, the frequencies failed on the pure tone screening and DPOAEs were congruent in 100 percent of these cases, indicating good reliability between subjective and objective measures.
As expected, the results indicated that the screening criterion (20 vs. 25 dB HL) increased the failure rate of the initial screening. While 11 percent of children failed the screening at 25 dB HL (1 – 6 kHz) in 2018, 17 percent would have failed at 20 dB HL. Notably, the difference was far less at the rescreening (five children), emphasizing the need for the rescreen to reduce the number of false positives. Inclusion of 6,000 Hz also resulted in more rescreens, with 39 children (5% of total) failing the initial screening at 6 kHz only. However, of the six children who failed 6 kHz only at the rescreening, half had absent DPOAEs in the same ear, which was consistent with possible hair cell dysfunction.
The two children who received a diagnostic evaluation as part of this study were in K and third grade. Both were found to have undiagnosed hearing loss. One child had mild sensorineural hearing loss above 1,000 Hz bilaterally, and the other had profound sensorineural hearing loss in one ear and mild low-frequency conductive hearing loss in the other ear. In both cases, DPOAEs were absent, consistent with pure tone findings. Notably, these children failed the screening at 25 dB HL, including (but not limited to) 6 kHz; thus, selection of screening criteria would not have changed the outcome. Although the parents of both children expressed concerns about their child's hearing, the children were not sent for diagnostic testing before.
The study findings suggest that a school-wide hearing screening is beneficial in identifying more children with potential hearing loss as well as outer and middle ear problems. Although screening procedures affected outcomes, more research should be done before universal criteria can be recommended. Finally, although diagnostic testing after a screening is recommended, this study found that parents are not likely to follow up even when testing is offered at no charge. Barriers to follow-up compliance need to be evaluated further.
Acknowledgement: The author acknowledges the contribution of Amy Myers, AuD, CCC-A; Emily Hamuka, MA, CCC-SLP; Sarah Black, BS; McKenna Dowdell, BA; and Connie Williams, MA, CCC-SLP, who assisted with this research. Also, thanks to Kim Norcross, superintendent of Phoenix Academy, for her support of the hearing screening program.
1. American Speech-Language Hearing Association. (1997). Guidelines for Audiologic Screening [Guidelines]. Available from: www.asha.org/policy
3. Dodd Murphy, J., Murphy, W., & Bess, F. (2014). Accuracy of school screenings in the identification of minimal sensorineural hearing loss. American Journal of Audiology.
5. Meinke, D.K. & Dice, N. (2007). Comparison of audiometric screening criteria for the identification of noise-induced hearing loss in adolescents. American Journal of Audiology.
6. Sekhar, D.L, Zalewski, T.R., Ghossaini, S.N., King, T.S., Rhoades, J.A., Czarnecki, B., Grounds, S., Deese, B., Barr, A.L., Paul, I.M. (2014). Pilot study of a high frequency school-based hearing screen to detect adolescent hearing loss. Journal of Medical Screening.
7. Allen, R.L., Stuart, A., Everett, D., & Elangovan, S. (2004). Preschool hearing screening: Pass/Refer rates for children enrolled in a head start program in eastern North Carolina. American Journal of Audiology.