Folded horn to capture very low freqs

Hi,
I am making a application that listening to human body sounds.
The sounds are in a bass range bellow 150Hz (20Hz-15Hz)
I am using a horn applied to the skin (like a wood fetal fetoscope to pregnants) to capture them
I need to decrease significant the size of it ( 23 cm height) and I thought about folding it.
Is there some limitation or "rules" to folding horns?

Thanks!
Anna

 

Hi John, thanks for your answer!
Do you have any idea how to capture this reflections in the best way?
Thanks