scattering calculation ISO 17497-1:2004

[ahms5]

I was drafting a submodule for the ISO calculation of the scattering coefficient based in the reverberation chamber method:

in order to provide all methods, which are required for the user to do the postprocessing of the measurement results. reverberation times, speed of sound and air attenuation are already assumed for this submodule. (can be calulated with pyfar.constants and pyrato)

I would suggest the following methods unter imkar.scattering.diffuse.*

• maximum_sample_absorption_coefficient(frequencies)->FrequencyData (returns 0.5 for the given freqeunceis)
• maximum_baseplate_scattering_coefficient(N)->FrequencyData (the table 1)
• calculation(reverberation_times, speed_of_sound, air_attenuation_coefficient, volume, surface_sample) calculates scattering, alpha_s, scattering baseplate, and alpha specular. reverberation_times (averaged over all measurement positions), speed_of_sound, air_attenuation_coefficient represents the values for all the test_cases (1-4) (could be another name)
• accuracy of the measurement results based on appendix A. same input as calculation but withour averaging the reverberation times.
• there are also some other conditions, which could be checked, e.g.:
  • A_1<=0.3*V^(2/3)
  • V>=200*N^-3
  • check vs max scattering baseplate
  • check vs max absorption coefficient of test surface
  • one method for all or one method for each condition could be introduced.
  • a dedicated imkar warning like imkar.ISO17497Warning which is raised it a condition is not fulfiled.

previously I was thinking about a class, but splitting up each step and make it independed of each other has a lot of advatages for users and maintainers. a draft for a class but for ISO 354 (absorption) was here #27