Long Flutter Echo in Big Hall

In this video, I’m clapping my hands in a big hall. The black surface is acoustically absorbent material. Even though it covers about 80% of the walls, the reverberation time in the space is very long. This is because of flutter echoes between the lower untreated parts of the parallel walls.

After recording this video, I have metrologically assessed the space in more detail by measuring the room impulse response with a class-1 sound level meter as part of my work as an acoustical consultant. BKL, the company I work for, offers world-class sound and vibration monitoring, diagnostics, predictions and assessments to recognized standards and guidelines. We guarantee the highest quality of acoustical services available.

The video was recorded in February 2021, near Vancouver in Canada.
Camera: iPhone 6S (audio/video has not been adjusted or edited afterwards)

[mulebeatsdrums]

Cool flutter! I'm an acoustics consultant in the UK and I'm currently writing a paper on flutter echoes, so had to ask: was there any absorption on the ceiling? It looks like there's some metal frames up there, but not enough to create much diffusion — with that much absorption on the walls, the obvious path for the flutter seems to me to be vertically, but I can't see what's up there.

[elenalohrey]

Dang it I don’t know why but hearing that flutter sends chills of pure satisfaction down my back 🫠

[alvarojesusnietoillescas]

Nice video sir. Did you record the IR at that moment? It would be nice to have such a fx profile for sound design. :)