Hearing Intervention Effects on Brain and Language Development in Children With Bilateral Mild Hearing Loss

The GDS-C was adapted from the 2006 Griffiths Mental Development Scales - Extended Revised (GMDS-ER) and standardized with Chinese norms for children aged 0-8 years. It evaluates six subdomains: (A) Locomotor, (B) Personal-Social, (C) Language, (D) Eye & Hand Coordination, (E) Performance, and (F) Practical Reasoning. The General Developmental Quotient (GDQ) is derived as:(developmental age ÷ chronological age) × 100. Higher scores indicate better overall developmental status.

Including six subscales: Locomotor (A), Personal-Social (B), Language (C), Eye-hand Co-ordination (D), Performance (E), and Practical Reasoning (F). Each subscale quotient is calculated as (subscale developmental age ÷ chronological age) × 100. Higher subscale quotients indicate better performance in the specific domain.

Brain structure and function changes evaluated by MRI

Electrical potentials recorded with scalp electrodes in response to electrical stimulation of the cochlear nerve. The ABR threshold will be measured in decibels normal hearing level (dB nHL) for each ear. Lower thresholds indicate better auditory function.

Behavioral audiometry measures the lowest pure tone level children can respond. Its thresholds will be measured in decibels hearing level (dB HL) for each ear at standard frequencies. The Pure Tone Average (PTA) will be calculated by the average of four frequencies (0.5, 1, 2, 4 kHz). Lower thresholds indicate better hearing.

Measured by percentage of correctly identified words (ranging from 0% to 100%) from standardized Mandarin Chinese word lists, presented in a quiet sound booth. Higher percentages indicate better speech perception ability.

The Categories of Auditory Performance (CAP) is a hierarchical rating scale assessing real-life auditory functioning. It comprises 10 categories graded from 0 to 9, where 0 = "cannot detect environmental or speech sounds" and 9 = "able to use the telephone with an unfamiliar speaker in unpredictable situations". Higher scores indicating better auditory performance.

The Speech Intelligibility Rating (SIR) is a hierarchical rating scale assessing the intelligibility of a child's speech in everyday communication. It comprises 5 categories graded from 1 to 5, with higher scores indicating greater speech intelligibility.

This scale includes the original MAIS version for children aged ≥3 years and the IT-MAIS (Infant-Toddler version) for children <3 years. It is a parent-report structured interview designed to assess the child's spontaneous auditory responses in everyday environments, consisting of 10 items evaluating three domains: vocalization behavior, alerting to sounds, and deriving meaning from sound. Each item is scored from 0 to 4, yielding a total score ranging from 0 to 40. Higher scores indicate better auditory integration ability.

The Meaningful Use of Speech Scale (MUSS) assesses speech production and communication ability. It comprises 10 open-ended questions answered by parents/guardians, each scored 0-4). The total score ranges from 0 to 40, with higher scores indicating better speech use. Scores are often reported as percentages (score ÷ 40 × 100%).

The ABAS-II is a comprehensive, norm-referenced assessment of adaptive functioning across multiple skill areas relevant to daily living. Depending on the respondent form used, it yields a General Adaptive Composite (GAC) as an overall standard score (mean = 100, SD = 15), three domain composite scores (Conceptual, Social, and Practical), and individual skill area scaled scores covering domains such as Communication, Community Use, Functional Academics, Home Living, Health and Safety, Leisure, Self-Care, Self-Direction, Social, Work (where applicable), and Motor. Higher scores consistently indicating more advanced adaptive functioning.

DPOAEs were recorded bilaterally at standard frequencies. For each frequency, the DPOAE amplitude (in dB SPL) and signal-to-noise ratio (SNR, in dB) were obtained. The amplitude represents the absolute sound pressure level of the distortion product response, while the SNR is the difference between the amplitude and the background noise floor at the same frequency. Higher amplitude and SNR indicate stronger outer hair cell (OHC)-mediated cochlear amplification and better cochlear function. A DPOAE response is conventionally considered present (PASS) when the SNR exceeds 6 dB.

Acoustic immittance is measured via tympanometry using a 226-Hz probe tone. Three quantitative parameters are reported: tympanometric peak pressure (measured in daPa), peak compensated static admittance (measured in mmho), and equivalent ear canal volume (measured in mL). Results are classified as pass or fail based on standardized criteria.

Including basic family environment survey, and Index of Child Care Environment (ICCE)