jank measurements, featuring omni mic capsules worn at ear canal openings

Discussion in 'Audio Science' started by E_Schaaf, Mar 12, 2019.

  1. E_Schaaf

    E_Schaaf MOT: Upscale Audio (Thread Judge Code-6 District)

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    Out of curiosity I plugged my Soundman OKM II 'binaural' mic into the 3.5mm mic input of my laptop, fired up the demo version of ARTA, messed around with the settings a little bit (no compensation curve), put the mics in my ears, and took some FR measurements of some of the headphones available to me at work. These are certainly unsanctioned.

    All of them show a suckout around 6k-9k, which I suppose is related to reflection off of my eardrums causing some phase cancellation. This is likely due to the distance from the transducers to my canal opening to the eardrum and back. Like comb filtering starting in the lower treble. The bass through mids responses shown do tend to reflect how I hear relative differences between these headphones to some degree, though I've always felt Marv's flat plate measurements most tightly align with my ears.

    Not sure how reliable the high frequency measurements are outside of these dips. The dip moves a bit given the mic isn't perfectly fixed in position in my ear canal and sometimes shifts as I switch between headphones.

    I measured each headphone multiple times until I was satisfied with consistent results. Wish I had HD650 on hand for reference.

    Focal Clear:
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    Focal Elear:
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    Focal Utopia:
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    Focal Stellia:
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    ZMF Atticus:
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    ZMF Eikon:
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    ZMF Aeolus (Perf Universe Pads?):
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    ZMF Auteur (Perf Eikon Pads):
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    ZMF Verite (Perf Universe Pads?):
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    Not sure if it's worthwhile to concoct a compensation curve for this rig or simply start from scratch with a more traditional setup. I don't trust this rig in it's current state to represent distortion and CSDs reliably.
     
    Last edited: Mar 12, 2019
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  2. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    I think you need to put the mic in a dual or tri flange tip with hot glue. You don’t want it totally flush with the tip’s end, but extended out a bit so the mic and glue make a sort of cone shape out of your ear canal. Ideally the mic will sit just slightly out of the ear canal entrance. Mostly flush, following the natural curvature, but out a millimeter or two.

    Total seal is important with all this.

    Sometimes filters over mics will do weird shit like this.

    It could also just be causing a really peculiar resonance situation for you. Some sort of room effect in your pinna.

    I wouldn’t expect the mic itself to be doing it...But you should check whatever mic input and PSU you have to make sure they aren’t causing FR anomalies. Loop back test would be a good start.

    If you have windows 10 make sure it isn’t doing it’s own sound processing nonsense.
     
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