tl;dr: analyzing the sound of a balloon popping in Hagia Sophia, they made an audio filter using techniques and understanding of sound in space that only became available in last 10 years. Cappella Romana made an album called Lost Voices of Hagia Sophia using this filter to recreate the experience of listening to Christian chants in that space. It's available on Spotify, headphones probably best.
> they made an audio filter using techniques and understanding of sound in space that only became available in last 10 years. This is an old technique. The idea of convolving the impulse response of a system with an input to yield the output is the basis of LTI systems theory. And while convolution isn't the most computationally light operation in the world, computers have been up to the task of practically performin…
I think the reason they used balloon pops was because that was all they were allowed to use: many heritage or archaeological sites can be nervous about researchers bringing in large loudspeakers and amplifiers, whereas a portable recorder and a bag of balloons can feel a little more harmless. Most acoustics researchers are aware of and use those new techniques whenever it's possible!