Hey, I'm currently working on a sci-fi short film in which the majority of action takes place in an abandoned cellar underground. The director wants bassy, rumbly factory/machinery sounds coming from the floor above.
I thought this should be easy to just fire up some Logic Space Designer IR, roll off the top end and be good to go, but this just sounds muddy and undefined.
How do you guys go about making sounds coming from the floor above?
I agree with Internet Human's approach, I think physical baffling is the way to go. I have found success in the past by actually using the floor of my previous house. I needed to record footsteps (and a fight) from above, so I set up 4 mics in the basement facing upwards about a foot below the ceiling, and then I had fun running around upstairs, slamming my body down, kicking furniture, etc.
If you can access a house (particularly a wooden one) with such a basement, try recording a few impulse responses through the floor. What this will get you is a feeling of resonance and size that smaller baffling can't really duplicate. A large, wide floor, especially in an older house with less rigid supports, can act like a "diaphragm" of sorts and resonate low/low-mid frequencies quite well. It might take a little location scouting, but I bet the results would be worth it.
You can also try "worldizing" (re-recording through a speaker in a real acoustic space) your sounds in various interesting acoustic spaces. I'd go for a stereo recording at a minimum, but multichannel would be even better. A few that come to mind:
If you have Altiverb or access to it, the "Next Door" set of impulse responses is quite reliable for these kinds of sounds. You can always blend back in the original sounds in the mix for clarity.
Best of luck!
~Matt
Setup something physical that can block the sound, so you'll get natural filtering. Then depending on whether you have a prop for the sound or a sample, either use the prop or play the sound from a speaker and record the sound from a position, where the sound is blocked. I imagine something like a closed door and some distance could be a good start, or at least it would be worth trying, how it sounds. Or it may provide a base for further small eq adjustments.
Sounds like a nice challenge. These sounds coming from a floor above us are often a little difficult to create because you're walking a thin line between 'just low rumble' and 'too clear sounds so they don't seem to be enough next-door-sounding'. But I think you should be aware that once you have a range of sounds that are believable you can use them to influence the mood of the scene in quite a major way, exactly BECAUSE they are so difficult to indentify, so they work even more unconcious than sound normally does! If you have different options like, for example, aggressive/ wide/ howling/ weeping/ whatever you need, you can sometimes use them almost like music, if the film leaves room for that.
As for the techniques: I would recommend recording real things that are big and far away/ next door, pitching stuff down, filtering it, reverb, massive granular synthesis can make things sound huge... Also go mad with completely unrelated sounds that can be made to sound machinelike.
