What does my chaffinch want?

There is a chaffinch in the tree in my garden. He is constantly making a noise every second. Its a single noise and not a song. It is a male chaffinch and will do this noise for hours and hours. Pretty much all day only stopping when he briefly feeds or when the sun goes down. It is not like any chaffinch call ive ever heard and the mating season is over (it being end June now and their mating period is supposed to be April). Ive reasearched their calls and it is definately not this and I am absolutely certain its a male chaffinch. Ive grown fond of the bird but the noise is irritating a lot of my neighbours. One of them shoots squirrels im worried he might shoot this bird if it continues to annoy everyone. What causes a bird to change its call? Ive clapped my hands at it to tests its hearing. It moved to another branch when i did, but that could have been from the vibrations of the clap. Any light on this subject would be amazing thankyou.