PUREPATHCONSOLE: Thermal Measurement Test Stimulus & SOA

Hello

Just wondering if  you can give some background on the Thermal Measurement Test stimulus during the speaker characterization using the Learning Board within the Purepath Console?  I notice the test signal rises in level and stays at that level for about 40 sec.  Then turns off and turns back on at that last level.  Why does that Power slowly decay to a lower power than when first excited with the highest level stimulus? 

Also, for the SOA Power Limit, can you explain Watt continuous?

Thanks

-Mike