Hello Angus and welcome to the Cow Audio Forum,
You have run into the wall of Physics.
Try this. Open the door, step outside. Place talent and mic, hit record.
Even outside spaces have their own "room tone" (ambience tone?), so you may have a problem there, but at least you won't have room reflection problems.
The louder the voice, the more problem you'll have because the louder the voice the more it excites the space around it. Like blowing into a pop bottle to make it sound a tone, any space has one or more resonant frequencies. Put enough energy into a space and you will find those resonant frequencies.
Outside, the sound is not contained and just disperses.
Regards,
Ty Ford
Want better production audio?:
Ty Ford's Audio Bootcamp Field Guide
