Hotpoint Superplus 7822 dishwasher

Check to see if there is water in the bottom of the DW after the buzzing sound is over.
If the water valve engages and no water flowing (Because water valve is turned off), it will make a buzzing sound
If not the problem, try to isolate the specific cycle time in which the buzzing sounds

it is a capacitor to start the motor for the next cycle. I think it is inside the door. you may have to call a tech.

Sounds like there is something in the filter trap that is right before the mini disposal that is a fan blade, on top of the motor.

Many Frigidaire dishwashers come with the promise of being the "quietest dishwasher in its class," according to Frigidaire. However, a quiet dishwasher doesn't necessarily mean that the dishwasher is silent, as some noises are normal. It can take some troubleshooting at times to determine if a noise coming from the dishwasher is typical or if it indicates a larger problem Listen for the sound of water filling and draining throughout the wash cycle. These sounds are normal and do not indicate an issue.

2 Pay attention to the drain motor, which operates at the beginning of each cycle. This noise should be fairly quiet and should not sound like a loud, grinding or banging sound.

3 Note that the sound will change when the wash cycle moves between the lower and middle spray arms. This sound should be temporary and fairly quiet.

4 Look for hard items in the dishwasher grinder or filter if a loud crunching, buzzing or grinding sound is heard. The dishwasher can typically grind up these items within one or two cycles, but the item may be lifted out and discarded to eliminate the sound.

5 Remove the bottom rack and spray arms from the bottom of the dishwasher if there is a loud noise coming from the dishwasher that does not resolve itself. Look inside for the impeller, which is round and spins. Remove any debris that may be clogging up the impeller or pump.

No longer "ultra quiet" huh?

A sound during certain cycles indicates a broken part. By the information provided sounds like a pump may be the problem. You may need to contact a service tech about this issue. If the appliance still under warranty, the service should be provided for free.

Every time when you hear noises (other than the normal ones) in the appliance, it indicates there is something wrong and it will worsen over time, so as soon you hear something is not ok, get assistance.

check pump strainer

dear sir the problem you have sounds like the solenoid that opens the drain actuater can be worn out open the bottom panel run tru a cycle observe when the solenoid open it may be that there is something causing the solenoid to buzz either worn out or a wire or something in the way causing not to close proprly thanks from gilles

This buzzing sound can be from a couple things. A lose a lose kick/access panel when the motor and pump is in operation can cause a slight vibrating noise. Try tightening securing the dishwasher and kick/access panel.

Second, (most likely) their can be an obstruction or debris in the water pump. You may see a plastic grid (4" x 6"; filter like) in the right rear of your dishwasher; Try removing the grid (1 or 2 screws 1/4"/cross tip), then use a dry-vac to remove any debris. *

Safety: As a beginning, please remember to perform the repairs with the power-off and ensure you have water in the dishwasher before restarting the water pump cycle (the water-pump can become damaged while dry-spinning and water enters the pump suddenly)

Hi.
The filter basket in the bottom could be blocked, but it is more likely the outlet hose having become full of foul smelling gunge.

You could try filling the machine with very hot water and plenty of dishwashing detergent, running it without dishes for ten minutes and then pumping it out to get plenty of hot detergenty into the drain pipe.

If you want to be economical you could aim the drain pipe into a bucket on a chair to catch the emerging water and go through the process a few times to try to clean out the pipe without wasting water or detergent or energy.

The contents of the bucket after the first run will give you an idea if you are on the right track.

If these suggestions do help you solve the problem, please give my reply a rating to help others judge my knowledge / guessing skills. If they do not, please add a comment with more details so I can try to help you further.
Cheers, D