Headphones

Such has been the decades-long emphasis on controlling structural and diaphragm resonances in loudspeakers that HFN's lab reports often carry cumulative spectral decay (CSD) waterfalls in which resonance barely features, at least at treble frequencies – measurement at lower frequencies is tougher. CSD measurements are rarely applied to headphones, suggesting that designers have not addressed this issue with the tenacity of their loudspeaker cousins. Many modern 'phones have readily identifiable structural and diaphragm resonances, with planar magnetic types often some of the worst performers. There's a widespread assumption that because PM diaphragms are driven evenly across their surface they must be resonance-free, but this is not true. However, we don't have the knowledge or tools to assess whether these resonances are audible and, if they are, what effect they have on sound quality. All that's certain is that zero resonance is the ideal – and one that many headphones fall far short of. KH