@JimmyT said:
OK, do you have a “smart phone” with a voice recording facility. If not, go HERE and look at your options to by a simple digital recorder.
You could also get a simple microphone and connect it to your PC. A recording at a far higher quality than you are likely to need (mono, 22,000 samples per second, 16 bits per sample – like I said, almost certainly far better quality than is necessary, but overkill is better than underkill), uncompressed, for ten hours will weigh in at about 1.5 GB. You can then transcode to MP3, which will be much smaller. I would record the date and time at the start of each clip, and let it run uninterrupted. Enough of those clips showing the noise should be enough to demonstrate malicious intent.
Good luck.