# $\rho$, $K$ and the future of ISO 10534-x

1. ISO 10534-x series currently describes "surface" measurements
2. But we can do more with impedance tubes : measuring "intrinsic" quantities
(such as $\rho$ and $K$)
3. So here are changes submitted to the standard series

Follow & play with these slides at:
http://apmr.matelys.com/2020_Lyon/

video at https://youtu.be/T6FgXPTpNQA

The main motivation for this work can be summarize as :
We can do more with an impedance tube than just measuring the normal surface impedance $Z_s$, the normal reflection coefficient $R$ and the normal sound absorption coefficient $\alpha$ for a material sample.
Indeed, we can assess the dynamic mass density $\rho$ and the dynamic bulk modulus $K$.
These complex quantities are intrinsic to the material and they are related to the material parameters (such as the 6 ones of the Johnson-Champoux-Allard-Lafarge model for example).
We propose changes to the ISO 10534 series, describing the assessments of these 2 latter quantities $\rho$ and $K$ (which are directly related to the characteristic wave-number $k_c$ and the characteristic impedance $Z_c$ of a material).

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