Hindu - Ohm related question

[ohm]

Our neighbours are Hindu.

About 6:30am every morning they do a deep ohm type mantra loud and repeatedly.

I find it quite annoying as it wakes me up but would like to be more sympathetic with a little understanding.

Can anyone tell me the connection or what it means to do this?

I am sorry but I will not ask them as I don't want to make them feel uncomfortable about it or them consider it to be a complaint.

Thanks

People will attach different meanings to it

but they are being loud at the crack of dawn, just talk to them about it.

Well - Aum is a sacred mantra, representing the entire universe & embodies the sound of creation. They may well use it as a prayer as part of their puja/worship, or it might be meditation related. But you wouldn't be unreasonable to talk to them about it and ask them to do it in a different room or more quietly.