The brain speaks in layered rhythms, not single tones — and for decades, the tools we used to listen could not tell the difference between genuine conversation and mere echo. A research team has now introduced a mathematical framework, built on antisymmetric polyspectral indices, that detects true multi-frequency neural interactions while filtering out the phantom signals created when electrical current spreads through tissue. Published in Nature, the work addresses one of neuroscience's most persistent measurement problems, offering a more faithful way to hear how the brain's many oscillation