Headphone Soundstage and Imaging: Definitions & Measurements

Discussion in 'Blind Testing and Psychoacoustics' started by samvafaei, Apr 23, 2018.

  1. briskly

    briskly Friend

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    • Distance from the sound source, yes.
    • Phase correction would be necessary as a part of compensation curves. Magnitude shifts impose their own effect on the phase, and the group delay as a consequence. Since you brought it up, I don't think group delay can appropriately be defined beyond the envelope of the waveform. That is, how the spectrum is superposed. If you assert group delay as a strict measure of information, then this admits certain conflicts with causality.
    • CSDs are STFTs with a rectangular window function applied to the impulse. Group delay would shift the envelope of lower frequency content forward. This includes both the initiation and the end tail.
    • By free-field, I meant facing the speaker directly. That is how the standards normally define the free field. It isn't very much like ordinary 2 channel listening.

    What's not clear to me is how the PRTF is being used to incorporate the directivity of the ear. If this were all that were needed, amplitude shifts can be easily encoded into the signal. In a room, however, the early reflections scatter over the ear from different angles, yielding additional cues. Given the size of headphones, I don't find it so plausible that time interval leads to easy isolation of the first sound to correlate to the very short time reflections.
     
  2. MF_Kitten

    MF_Kitten Banned per own request

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    Apologies for the bump, but I am still struggling with the idea of soundstage/width, in terms of what actually causes a pair of DT880's to sound insanely wide, while HD600/650's are known to be super narrow and "in your head". HD600 and DT880 are similar in general tonal balance (beyer treble spike aside). The Beyers are actually LESS open than the Sennheisers here, with the DT880/990 having cups with a coin-ish size hole in the middle back of the cup, and a grill outside of that.

    Messing with RePhase and flattening the phase response of my cans based on measurements, I am starting to think that phase is a big part of this. I'm not sure how you can maximize soundstage with phase adjustment though? If you could really define what the phase needs to be doing in order to get a wiiiiiide sound, you could induce that with phase adjustments in DSP.
     
  3. MF_Kitten

    MF_Kitten Banned per own request

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    I'm just going to back myself up here... After looking up some headphobes that have wide soundstage, and thinking about what that means, I noticed the same thing in all the measurements: the low mids/mid bass have a big phase dip. From my experience in actually making and mixing/mastering music, I know what that actually means. Not only is that the range where we perceive width the strongest, but that phase difference is going to reject the "middle" image in favor of the "sides" image in that range. I am willing to bet that I can replicate the sound of super wide headphones in a track, and I bet you can use rephase and a minidsp to create soundstage that rivals the hd800 or DT880 or whatever.

    I have plans to actually test this :)
     
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  4. purr1n

    purr1n Finding his inner redneck

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    You can feed reverse phase of opposite channel to increase width. I don't recommend it as I'd prefer a modicum of depth to extra wide super special headstage.

    Crossfeed helps with depth, but getting the EQ right is tricky.

    The openness thing is mostly related to transient response (it's damped in a closed or partially closed system) and possibly lack of reflected soundwaves back through the driver. People who have experimental with OB speakers such as @sphinxvc, @Hooncake, @zerodeefex, @Donald North totally understand this and will probably never go back to box speakers. Note that lack of isolation also contributes to less damping of the transient response as there is still a chamber inside the cups between ear and driver.
     
    Last edited: Jul 28, 2018
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