Does the sound of water dripping into the fish tank from water pump or filter bothers the fish?

No the filter noise wont bother them. Stand beside a small waterfall or rapids in a river, it's noisey, the fish dont care.

As for your bacterial bloom, try doing smaller water changes. more often, 25% at a time.

What may be happening is your tap water has traces of phosphate / nitrate etc When you add this to the tank the extra nutrients encourage a bloom of algae, diatoms or bacteria and the water goes cloudy for a while. Then things settle down, untill the next big water change. Smaller water changes, less cloudiness and it will clear up faster.

Ian

Stand by a river and listen to the noise it makes then compare that to your tank noise. The river noise is probably just as loud or even louder than your tank. The fish probably dont mind then

never turn off the filter that will kill the hundreds of good bacteria

Never change more than 30% of the water a week and also how many goldfish do you have and what sized tank do you have?

2 goldfish! never turn off that filter:D...it wont bother them for all they know its reaning in one spot of the pond:P might bother u but thats another story...if u have to do 75 u need a bigger tank...just the chemicals u use to treat the water...no need to worry usually benifical bacteria that are loving the amount of ammonia ur fish give off:D

leave the filter on, fish live in rivers and streams, not exactly quiet, not sure on the bloom

Nah, their brains are micro. As far as the bacteria..not sure, but it seems to even out once filtered tho right?

fish has hardly have any sense of hearing, especially gold fish.