Sound Iridescence

Trying to make something which creates Acoustic Iridescence

Light iridescence gives butterflies their shimmering colours. The minute structures of the wings give this beautiful structural colour via interference effects. This means as you turn the butterfly around and look at the wings from different angles, the colour of the butterfly changes (animation of this). The structures also makes the colours incredibly intense.
I can’t think of any iridescent sound structures in nature. What I need is a surface which reflects sound with different acoustic ‘colours’, one where the sound changes frequency (pitch) as I listen at different angles. Current plans involve a large quantity of perforated metal.
What I’m doing today is trying to generate some sound files which simulate what might be heard. This is what it sounds like, if I ‘illuminate’ the surface with noise:

It’s very satisfying to hear the pitch increase – what a shame it sounds horrendous. I certainly haven’t produced a sonic beauty to compare to the butterfly wings.
Acknowledgements: Blue Morpho butterfly image (Morpho menelaus) by Gregory Phillips.