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Impedance Tube Parameter Estimation with Data Generation
Posted 15 feb 2024, 11:12 GMT-5 4 Replies
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I've utilized this tutorial (https://www.comsol.com/model/impedance-tube-parameter-estimation-with-data-generation-71561) for parameter optimization, which was originally tailored for synthetic data generation and subsequent optimization of five JCA parameters. However, my specific need entails importing experimental sound absorption data obtained from the impedance tube method, and then conducting parameter optimization for the same set of five JCA parameters to fit the experimental data. Could you please guide me on how to adapt the provided steps to accommodate my requirement? Thank you for your assistance.
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Hi Pramodya,
The model you linked uses data for pressure vs. frequency measurements for the two microphone method. So the data used for the optimization is the complex frequency for two different points. In the model, there are corresponding probes that are setup for the pressure for each of the measured points.
If you only have absorption coefficient vs. frequency data, load this data into the Parameter Estimation Study. Then in the model, compute the absorption coefficient and use this as the model expression value in the Parameter Estimation study, instead of the point pressure probes.
Note that just using the absorption coefficient magnitude vs. frequency does not contain any phase information that is present when using the microphone probes. So likely the optimization will be better if using the two microphone complex pressure or complex surface impedance from the measurement if you have that data available.
-Mark
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Hi Pramodya,
The model you linked uses data for pressure vs. frequency measurements for the two microphone method. So the data used for the optimization is the complex frequency for two different points. In the model, there are corresponding probes that are setup for the pressure for each of the measured points.
If you only have absorption coefficient vs. frequency data, load this data into the Parameter Estimation Study. Then in the model, compute the absorption coefficient and use this as the model expression value in the Parameter Estimation study, instead of the point pressure probes.
Note that just using the absorption coefficient magnitude vs. frequency does not contain any phase information that is present when using the microphone probes. So likely the optimization will be better if using the two microphone complex pressure or complex surface impedance from the measurement if you have that data available.
-Mark
Hi Mark, Thank you very much for your response. I understand the method you descibed and will follow with parameter estimisation. I have impedance ratio for microphones which I also got from impedance tube. So could I use that at the two probes?
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Yes, provided you computed the equivalent quantity in the model and use it together in the optimization.
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Yes, provided you computed the equivalent quantity in the model and use it together in the optimization.
Thank you Mark!Will try and update!