Arrest it please.

One of two things are generally responsible,high water pressure or loose washer. Unless you have this at other toilets and/or faucets we will assume loose loose washer and that you know how to replace faucet washers. Check washer screw in angle valve to see if it's snug. Tighten if it isn't snug,reassemble and and hope hammer is gone. If that doesn't cure it you can try replacing ballcock washer (not all have replacable washers) . If washer isn't replacable or new washer doesn't fix it you will need to replace ballcock. If you aren't piticularly handy with minor plumbing repair I suggest finding valve located near floor beneath toilet and turn it clockwise 1/4 turn. If you hear the hammer next flush,turn another 1/4 turn clockwise. Continue this routine until hammer stops or water ceases to fill tank. If there's no joy you will need to replace ballcock. Good luck

I'm not the most handy with plumbing stuff but I will give that a shot. I didn't think a faucet would impact flushing but this is not my forte. It's a relatively new house so I'm a bit surprised I would have an issue so soon.

I have new information to share on this:

The sound occurs upon the flushing of either of the upstairs toilets. Essentially what happens is I hear loud whooshing noises in the drain of the tub in my primary bath. One or two times when flushing the primary toilet I also heard a knocking noise. When flushing the guest toilet I just hear very similarly loud draining noises in the master bath tub, not really the knocking. Why this is concerning is this is completely new. I've only just started hearing these noises in the master tub from either of these toilets flushing. The house is only a little more than one year old. Should I be concerned? Is it a build defect? Again we never flush anything other than TP down the toilets. Thanks!

I can try to post audio if that would be helpful.

Trap in tub drain might be dry,run a gallon or so of water in tub then see if wooshing sound diminishes. Wooshing and hammer is not related. Now that you say two toilets hammer I suspect it is caused by type ballcocks.

Well I have yet to use my tub so it makes sense that the trap would be dry. I will give that a shot

that actually worked!!! does this mean I don't have to worry about these ballcocks? (Trying not to laugh at this word...)

What do you mean by " does this mean I don't have to worry about these ballcocks?" I don't know why being rid of woosh makes hammer less annoying. I've done my best to answer your questions,can you please answer mine to help me better understand people.

It probably wasn't actual hammering that I was hearing. The sound in the bathtub drain was so loud I thought maybe that's what I was hearing. Because there is now no noise at all when I flush.

Thank you , that's certainly a lesson in understanding people.

To wit, slow questions deserve slow answers, fast questions deserve fast answers and half fast questions should receive half fast answers..