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Monday, August 6, 2012

Introducing my 60318-4 occluded ear simulator


This is the 60318-4 occluded ear simulator I use for IEM measurements, with the conically-concaved proprietary external ear adapter attached. A pair of these are encapsulated in my dummy head, EURI, as well (level difference less than 1 dB from 20 to 20,000 Hz). Last time I got a quote from BSWA USA in April 2011, the price of this simulator was $3150 each.


Above is the calibration chart I received from the manufacturer, and the simulator has an acoustic input impedance effectively matching that of the human ear canal.

9 comments:

  1. Very Nice...

    Jim

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  2. Is this different from the GRAS RA0045 and B&K 4157? Has IEC 60318 been revised from 60711?

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    1. They are all equal, at least with the acoustic impedance, due to dual-ring helmholtz resonators implemented. And yes, it is a revised version of the IEC 60711 standard.

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    2. What are the differences between the standards? I can't seem to find a listing...

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    3. changed some of terms & added measurement circumstances, as far as I know. And the diagram looks nicer. Also,

      - extension of the usable frequency range to 100 Hz - 16 000 Hz;
      - addition of values of maximum permitted expanded uncertainties to all tolerances.

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  3. I have a question: if I measured a earphone with a 2cc coupler and applied a RECD compensation curve, would it give me a rough idea of how "flat" the response is compared to a real ear's response?

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    1. A 2cc has its own acoustic input impedance characteristic, and the degree of resulting SPL deviation might vary depending on the amount of acoustic output impedance a transducer has.

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    2. Wouldn't that occur with every type of coupler then? I guess I should say that the RECD compensation would be specific to the 2cc...

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    3. My 2 cents. better to be done than said: Upon the compensation, you will notice the corrected response look a lot different than expected, and the same compensation technique is not universally applicable to all IEMs.

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