The ballcock is bad. Replace it.
ANS 2 - It's inexpensive and easy to replace with new style fill valve. Ballcocks are inefficient and prone to problems. Go to any 'big box' store and look at new Valves like Fluidmaster A 400, Pro 45, or similar - less than $20 and can be fitted in a half hour .
turn your inlet tap on fully and then return back to 1/4 on
When a toilet is flushed, the rushing water creates vibrations in the pipes, which can produce a high-pitched noise due to the rapid movement of water and air in the plumbing system.
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.
When a toilet makes noise when flushed, it is usually due to air being pushed through the pipes, causing vibrations and sounds. This can happen if there is a blockage in the pipes, a faulty valve, or air trapped in the system.
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.
either the vert is plugged and there is no air getting through or there is no vent at all
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
The discharge line (soil ) may be slightly back pitched so it takes longer to drain
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.