Looking for advice on low frequency noise coming from condo common element
I'm looking for advice on dealing with low frequency noise coming from my condo's comment element (indirectly from heat pump). It's a pulsing low frequency noise that hums 3 times per second and I have already complained to the condo manager about this noise and they sent engineers to reduce the noise. I didn't notice any difference in the noise reduction and the condo manager said they couldn't find the source of the majority of the low frequency noise. The noise happens when the heat pump is on and goes away when the heat pump is off. However, the noise is not directly coming from the heat pump. This low frequency noise started earlier this year, and wasn't there before in the previous 5+ years. What else can I do?
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