I have a small mic "booth" in my studio comprised of three EQ Acoustics L10 tiles, and a carpet below. I want to know if adding a fourth absorber to close the top or "roof" makes a substantial difference with regard to perceived reverberation on the recordings.

0:00 with open top 3:10 with closed top (additional absorber) 5:37 series of A/B comparisons 6:35 A/B for background noise 6:47 A/B comparisons with sounds pitched down by two octaves

To make any judgement, you'll have to wear headphones. I found the difference not as pronounced on the recording as perceived when standing in the "booth". Towards the end, there are pitched down versions which of course emphasise the reverb durations.