Noise from Well Tank

My 20 year old well pump works fine building up pressure, but when it stops I hear a quick series of noises coming from the tank. It is 5-6 who-hoo-hoo-hoo-hoo noises over about 1.5 seconds. They are not very loud and decrease in intensity from beginning to end of the series. The noise sounds like combination of a whease, moan or, sob and laugh, perhaps with a slight rub or low squeak to begin with underneath the noise. As it happens the water gauge goes down quickly.

What is it and what do I do about it? Thanks.

That many human noises coming from the tank sounds like it would make a funny utube video. If the pressure drops as soon as the pump shuts off, the check valve on the pump is probably bad. Tanks don’t usually make noise unless water is entering or leaving the tank. A bad check valve could cause the pump to cycle on and off enough to destroy the bladder in the tank. If the noise you hear is the bladder rubbing the tank, it won’t last much longer.