Mike Stranks wrote:I apologise in advance that I shall be blunt...
The Zoom and an SM58 are nowhere near accurate - or neutral - enough to let anyone judge anything apart from, "Yes, that was some noise." And noise-meters are not worth pursuing in an amateur context.
Having been involved in an informal 'neutral third party' noise assessment a few years ago, the other aspect is that, of course, the aggrieved soon notice every sound and noise emanating from the complained-of premises.
I could go on about my experience, but it won't advance the discussion any.
My tuppence...
1) Once social isolation has ended try and face-to-face with the occupiers of the noisy flat. Not letter, email, phone-call, but talk. Have an acquaintance with you - not a family member - and try and keep it light and smiley, but being clear about the issues as you see them. Don't get into an argument... do your best to part on at least calm terms.
2) If you really want to get evidence follow James Perrett's advice and hire some proper kit and keep those logs.
I agree that I'm probably more sensitive to noise as a result of this ongoing problem but I think I'm still objective enough to be able to distinguish noises that I notice but aren't that loud and other people wouldn't be bothered by from noises that are very intrusive and would annoy most people, like screeching water pipes that wake you up at 2am and the thud of a football being kicked against the wall for hours on end. I'd hoped the latter had stopped after I spoke to my neighbour at No.21 about it but unfortunately it's just started up again after a few days of relative peace and quiet. I say relative, because there's still been the noise from the neighbours directly above me at No.22 stomping about and slamming doors but at least that only happens for a short time each time and it doesn't do my head in as much as the constant thud of the football for hours.
Clearly the Zoom and the SM58 are useless for recording these noises, so I'll return the Zoom. I don't think there's any point spending hundreds of pounds hiring professional equipment though, as the council aren't going to accept that as evidence when I have the key to the case and could have tampered with it. I don't think there's anything magic about the professional noise recorders, they're just calibrated, combine an SPL meter with a noise recorder and some features for analysing the recordings.
So I'm sure there must be a cheaper mic and pre-amp/USB soundcard I could buy that would record the sound to at least prove I'm not imagining it. If no mic can record the noise, then hiring the professional calibrated recorder for a week isn't going to help me and if I can get a recording of the noise, then together with my logs it will help me persuade the council that the noise is unreasonable and get them to investigate further.