Hello guys, I read the other threads about HR, resonances and so on, but I couldn't find a clear explanation of what the practical implications of using a HR are. From one side, HR is described as a "reactive element", used in several contexts to attenuate a specific noise by means of reflection (phase cancellation). From the other side, HR is used as a "sound amplifier", used in all sort of musical instruments to amplify their sound. My questions are: 1) A HR is characterized by a very narrow-band resonance, used to address unwanted noise components. However, if that is a proper resonance, that should in theory amplify that frequency instead of dampen it! Can you help explaining this phenomenon? 2) Each HR has a very narrow-band resonance, therefore it could "amplify" only a single tonal component. However, acoustic guitar/bass bodies effectively and uniformly amplify a wide range of sounds, without any notch or "blind spot" due to the HR noise-cancelling effect. How does this phenomenon relate to the HR theory?