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@jude what's your take on Hi-Res thing and do you think 40kHz extension matter for IEMs at all?...
@piotrus-g, I'm just trying to get meaningful headphone measurements out to 20 kHz, and haven't given this as much thought!
![KSC75 Smile :ksc75smile: :ksc75smile:](https://cdn.head-fi.org/e/headfi/ksc75smile.gif)
At the 2016 AES International Conference on Headphone Technology, Steve Temme from Listen, Inc. presented a poster covering this. From my notes and photos:
- His poster quoted David Griesinger: "The phase relationships of harmonics from a complex tone contain more information about the sound than the fundamentals."
- Temme asked, "So, why exceed 20 kHz?" His answers:
- "For a transducer to have a flat phase response out to 20 kHz, a flat magnitude out to 40 kHz is required (by definition, at resonance, there is a 90° phase shift)"
- "Inaudible high frequency components, e.g. 30 & 33 kHz resonances, can produce intermodulation products that 'beat' down into the audio band of frequencies"
- "A sampling rate of 44.1 kHz @ 16 bits adequately covers the range of human hearing and musical instruments"
- "To achieve a flat frequency response (mag & phase) out to 20 kHz requires a bandwidth beyond 20 kHz"
- "Loudspeakers and microphones that measure beyond 20 kHz can exhibit trade-offs in performance, e.g. audible intermodulation distortion"
- "Try down-sampling a hi-res audio file to CD quality and do an ABX listening comparison. Can you hear the difference?"
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