For a musician, keen tuning to the pitch and timbre of one’s instrument is important. For a bilingual, the distinctive pitch, phonetic repertoire, and cadence of one’s two languages are important. For an auto mechanic, the sounds coming from an engine in distress are important. The listening brain must respond optimally to the sounds a listener cares deeply about. The sounds of music, language, or pistons become prioritized over time – to become processed automatically, rapidly, and preferentially by an ear-to-brain system tuned to a default state, informed by efferent-modulated brain-to-ear plasticity. In other words, the brain shapes how the ear hears.