Description

1.1 Study Groups Each subject will undergo both PTA and OAE screening and be assigned post hoc to both TS-PO and SS-O groups with within-subject comparison of hearing screening outcomes.

1.2 Study Interventions In this study, we will compare the effectiveness of 1) TS-PO versus 2) SS-O in a community- based preschool setting to identify hearing loss. The interventions will be implemented in two distinct phases - a data collection phase, in which every subject will undergo both PTA and OAE screening; and group allocation phase, in which every subject will be allocated to both study groups (TS-PO and SS-O) virtually, for within-subject comparison.

1.2.1 Two-stage PTA+OAE Screening (TS-PO) Children will first undergo PTA screening, recommended for children aged 3 and older, using conditioned-play responses to 25 decibel (dB) HL pure tones at 1000, 2000, and 4000 Hz. Screening results include PASS, REFER, or UNABLE to test. Children unable to be tested immediately undergo OAE screening. Children who REFER either the PTA or the OAE test, or are UNABLE to be tested by both, are referred for further evaluation with their pediatrician. This two-stage method successfully screened 99.6% of preschoolers, with 3.1% identified with HL.

1.2.2 Single-Stage OAE Screening (SS-O) Children undergo screening with OAEs, detecting distortion-product OAEs in response to tone pairs centered at 2000, 3000, 4000, and 5000 Hz. Multiple studies support the efficacy of OAE hearing screening in preschool-aged children, with a success rate of 94% and identification of HL in 2.4%.

1.3 Study Timing and Duration Screening, recruitment, and enrollment will occur annually at each preschool site.

Hearing screening will take place annually. Diagnostic testing will be completed within 6 months of hearing screening.

1.4 Attrition and Study Withdrawal Subjects are enrolled at the moment of screening, and all possible outcomes (including failure or inability to complete screening and loss to follow-up) will be included in the final analysis, eliminating the opportunity for voluntary withdrawal or attrition.

1.5 Site Recruitment and Subject Enrollment Preschool site participation models vary based on whether site or study personnel perform hearing screening and case management. Three participation models are outlined based on who conducts screening and diagnosis.

Subject enrollment is performed by Site Personnel. A Screening and Enrollment Log (SEL) is maintained locally, with no identifiable information transmitted to the Study Team. Parents are notified of the hearing screening and study, with written or verbal permission obtained for screening. Children outside the inclusion age range (2.0-6.0 years) or with known permanent HL are not eligible. Children screened in previous years undergo annual screening, with only their first hearing screen used for analysis.

1.6 Study Procedures and Data Collection Screening Pathway Protocol covers site preparation, hearing screening, and screening outcomes. Screening Pathway Protocol involves screening personnel and training, including initial training and monitoring and quality assurance. Training levels of hearing screening personnel are defined as Level 1, Level 2, and Level 3 based on their screening experience. Data Collection involves collecting information on screening outcomes, equipment calibration, OAE and PTA screening protocols, PASS/REFER/UNABLE criteria, and randomization of test order. Randomization ensures unbiased test order presentation and is not related to group allocation.

1.7 Group Allocation

Group allocation occurs after Data Collection. Subjects are assigned to either the TS-PO or SS-O group based on primary data, including PTA and OAE results, hearing screen outcomes (PASS or REFER), and final hearing outcomes (HL or No HL). Allocation involves assigning PASS outcomes based on PTA and OAE results, while REFER outcomes lead to determining the actual final hearing outcome (HL or No HL). This process generates comprehensive datasets for both comparator groups for subsequent data analysis of primary and secondary outcome variables.