Hello Tom and welcome to the Cow Audio Forum.
You did a great job of explaining your situation.
A lot depends on, how sticky you are for details and little sounds.
If nothing’s outside the window making noise, that great. If not then you need to think about covering that window with a built out frame with more glass to provide a dead space that will hopefully be enough to knock down the exterior noise.
Or create your booth in a space that doesn’t look out the window,.
All foam makes for a very foamy sound…sproingy, especially with loud voices our loud moments, because the voices will be exciting the foam. A balance of foam and diffusion works best. The glass shouldn’t be too big because it’s just a large reflective surface.
The skinny side with the wall between the room and the hallway; is it carpeted? Hard soles shoe sound will likely transfer right under the wall and into your space.
5’6′ x 4′ is not a bad size. You will also probably want to look into re directing the HVAC in that space. If you don’t and anyone is in there for any length of time, it’ll get hot and stuffy. Small ducts increase the noise of air moving though ducts. That’s bad. I don’t know what your HVAC noise situation is right now but that’s something else to think about.
There’s another approach; use a frame upon which to hang sound blankets that surround the talent, including something to block the ceiling bounce and don’t forget to put a light in there so they can see to read.
How noisy is your computer? Present day machines can be pretty quiet. Unless yours is, a good mic will pick up that noise.
Regards,
Ty For
Cow Audio Forum Leader
Want better production audio?: Ty Ford\’s Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford\’s Blog