Maybe, maybe not, but an indicator to me is when I see a very nice drop in ringing as you have (evidenced by wide spacing between slices), and this continues until about 50-55dB, and then you have these tunnel tails coming out straight at you and actually rising in level (as shown in the purple waterfall). What else could cause an increase in the level as time passes other than outside influence noise). But I've been wrong before.I think you may have hit the nail on the head though
No, not if you measure the same speaker. The waterfall should be the same each measure. If the noise was consistent though, the measure would also result in the same display.Can a static room change it's reverberation times radically from measurement to measurement without some noticeable pattern if it's not noise?