It's something wrong with the pipes! One pipe is on too tight so it whistles when flushing.
Here is THE answer!!! I did it to my own toilet. A plumber came over to fix our stuck toilet... The first thing he did was turn off the water supply valve at the back of the toilet. Then he unstuck our toilet. When he left, he turned the water supply valve back on, but he turned it up to high. the water pushes the air up through the pipe and the pressurized air comes out the top little slits on the stopper thingamagigie. To put in words you can understand, it's like blowing a Flute.
The Fast fix is to do this... Turn the water valve one way and then another. You will know when the water flows faster because the whistling will still be there. What you want to do is SLOWLY turn the water valve to the off position UNTIL the whistling stops and then a little more. You now have water coming in, but not at a speed to pressurize the air and make the whistling sound!
My experience is when you flush the toilet, the fill valve opens and starts re filling the tank......sometimes if the water pressure is too high, it will "whistle". Close your fill valve until it stops whistling.....usually this slight adjustment will stop it from making that annoying noise
it's called stop holding down the flusher.
When a toilet bubbles when flushed, it is usually due to a blockage in the plumbing system. The blockage causes air to get trapped in the pipes, leading to the bubbling effect when the toilet is flushed.
When a toilet burps when flushed, it is usually due to air trapped in the plumbing system being released. This can happen if there is a blockage or restriction in the pipes, causing air to get trapped and then released when the toilet is flushed.
I do not know if popcorn can be flushed down the toilet. So, I wouldn't try it.- Ashton Smith
Toilet bubbles appear when flushed because of air trapped in the pipes or a partial blockage in the drain. This can happen even if the toilet is not fully clogged.
The sewer
Your toilet may be leaking from the bottom when flushed due to a damaged wax ring seal or a cracked toilet base. This can cause water to seep out when the toilet is flushed. It is important to address this issue promptly to prevent further damage and water wastage.
Depends on if it needed to be flushed or not.
Usually the water filling up the flush valve in the tank. If it's bugging you, you can change the flush valve to a new one.
Bad venting
Water and waste