Have you seen the latest Loudspeaker Industry Sourcebook?
Then you might have spotted our CTO Claus Futtrup and his article on Speakerbench, a web-based tool for converting your impedance measurements to advanced parameters. In the article he also discusses viscoelastic materials, the advanced model, compares with the Klippel analyzer, and how the results can be analyzed. The read is quite interesting for the loudspeaker enthusiast! You can find the article here at page 124. Speakerbench and the article in LIS was announced by AudioXpress.