From Early Music Audiometry to Tone Audiograms

BACKGROUND AND SCIENTIFIC RATIONALE:

Visual Reinforcement Audiometry (VRA) is the standard behavioral hearing assessment for children with a developmental age of 6 months to 2.5 years, achieving successful threshold determination in up to 92% of neurotypical children. However, testing success drops to approximately 50% in children with Social Communication Disorders (SCD) and Autism Spectrum Disorder (ASD). Incomplete assessments delay the identification and management of permanent hearing loss, impairing speech and language development. To improve test compliance, clinicians frequently present familiar music stimuli (FMS) in the sound-field. Some services apply manual band-pass filtering (BPF) to these music files to isolate discrete octave bands. However, current practice relies on time-consuming, non-standardized off-the-shelf audio editing tools, leading to high acoustic variability across centers. Crucially, the relationship between BPF-FMS behavioral response thresholds and gold-standard puretone/ warble-tone audiometric thresholds remains unknown in listeners with hearing loss, preventing clinicians from accurately plotting music responses onto standard diagnostic audiograms. This non-interventional basic science study utilizes a novel prototype software interface developed by Audio3 Ltd to deliver standardized, octave-band filtering of familiar music stimuli. The project evaluates the fundamental psychoacoustic threshold relationship between BPF-FMS, narrow-band noise (NBN), and goldstandard warble tones in listeners with confirmed permanent hearing loss.

STUDY STRUCTURE AND EXPERIMENTAL DESIGN:

The project operates across seven work-packages (WPs):

• WP1 (Management): Governance and steering committee oversight across the 17-month study lifecycle.
• WP2 (Filtering Strategy & Acoustic Verification): In situ free-field calibration and acoustic verification (complying with BS EN ISO 8253-1 across soundproof booths at Guy's and St Thomas' NHS Foundation Trust (GSTT) and CHEAR Ltd.
• WP3 (Clinical Setup): Finalization of research protocols, ethical approvals, and data management architecture.
• WP4 (Initial Data Collection - Phase 1): Comparative behavioral soundfield testing in 50 participants with confirmed permanent bilateral hearing loss (35 children/teenagers at GSTT; 15 participants at CHEAR Ltd).
• WP5 (Analysis & Optimization): Statistical modeling (Bland-Altman analysis and Linear Mixed-Effects Models) to evaluate threshold agreement between BPF-FMS and warble tones. The filtering parameters (bandwidth, slope, time-windows) are refined based on Phase 1 data.
• WP6 (Review Data Collection - Phase 2): Repeat testing protocol using the optimized BPF-FMS filtering strategy in an independent cohort of 50 participants (35 at GSTT; 15 at CHEAR Ltd).
• WP7 (Final Analysis & Dissemination): Final synthesis, reporting, and deposition of anonymized datasets to open science repositories.

TESTING PROCEDURE (PARTICIPANT EXPERIENCE):

All testing takes place in a single 15-minute session immediately following a routine, standard-of-care diagnostic hearing appointment:

• Setup: Testing is conducted in a soundproof booth meeting BS EN ISO 8253-1 standards using calibrated diagnostic audiometers (Otometrics Astera2 at GSTT; Interacoustics AC40 at CHEAR Ltd).
• Stimuli Profile: Participants are evaluated in the binaural sound-field at four standard frequencies (500, 1000, 2000, and 4000 Hz) under four distinct acoustic conditions: (1) Warble Tones, (2) Narrow-Band Noise, (3) BPFFMS Soundfile 1, and (4) BPF-FMS Soundfile 2. Unfiltered broadband music is also presented.
• Counterbalancing: Test condition order (1-4) is fully counterbalanced using 24 cyclic permutations to eliminate order, fatigue, and practice effects.
• Response Mechanics: Participants indicate sound detection via standard button-press mechanics in accordance with British Society of Audiology (BSA) recommended procedures.
• Recognition Assessment: Following testing, participants report whether the musical stimuli were familiar, unfamiliar, or unsure.

SAFETY AND DEVICE POSITIONING:

The prototype filtering software acts strictly as a signal-processing tool to standardize stimulus parameters and does not perform active medical diagnosis or treatment. Maximum volume outputs are hardcoded within the software interface to guarantee testing remains within safe acoustic limits. All hardware output devices remain unmodified, CE-marked medical audiometers calibrated to BS EN ISO 389 standards.

Inclusion criteria

• Aged 7 to 45 years old
• Able to reliably perform conventional Pure Tone Audiometry
• Confirmed stable bilateral hearing loss with a 4-frequency (500, 1000, 2000, 4000 Hz) pure-tone average ≥25 dB HL in the better hearing ear

Exclusion criteria

• Aged under 7 or over 45 years old
• Unable to complete reliable conventional audiometry task mechanics
• Satisfactory hearing or purely unilateral hearing loss (4-frequency pure-tone average in better ear <25 dB HL)
• Fluctuating or unconfirmed hearing threshold variations
• History of Auditory Processing Disorder (APD)
• History of Auditory Neuropathy Spectrum Disorder (ANSD)