There could be a logical explanation or there may be no explanation !
We once had large heavy bangs so loud the floor vibrated .....you'd run upstairs expecting something large had fallen over .....nothing.
Mother in law there here alone once reported a loud bang ....nothing amiss.
Once worked at a large industrial plant this rugby player a big lad was working alone one night and someone tapped him on the shoulder he turned round expecting to see a workmate ...nothing shrugged it off .......turned round continued working and it happened again.....he sprinted out of there !
Two years ago working at a house where no one was at home a tremendous loud bang from upstairs when the customer got home told them they went upstairs nothing.
Psycharatrist customer told me they'd bought this house 1600's where we were .......she heard medieval singing outside when she asked the neighbours who it was as she was a amateur opera singer and would like to chat with them, she was told there was no one in this cluster of half a dozen houses that could, sing like that
She was eventually told the hard nosed buisness people they'd bought the house ftom had had a priest round half a dozen times !
Readers decide for yourselves I'm merely passing on stuff I've come across.