This work presents a unified, neurobiologically grounded specification for auditory coding that integrates cochlear mechanics, spatial hearing, categorical perception, music processing, emotional evaluation, and speech generation into a single computational architecture. The model combines three mathematical principles—rate–distortion optimization, renormalization‑group dynamics, and group‑theoretic structure—to explain why perceptual categories across auditory domains (vowels, pitch classes, timbre clusters, emotional primitives, spatial bins) consistently cluster around 5–7 elements. The specification is biologically constrained, mathematically rigorous, and computationally implementable, with explicit links between neural mechanisms, formal derivations, and engineering applications. Appendices provide detailed proofs, including the extension of RD scaling to non‑uniform input distributions and a fixed‑point analysis of RG stabilization. The framework offers a unified account of auditory cognition and suggests improvements for hearing aids, cochlear implants, music AI, speech synthesis, and affective computing. December 24, 2025 — Christmas EveOn this quiet Christmas Eve, I simply offer warm wishes to all who continue to think deeply about the future of cognition and world‑modeling.