You could have one or more of the following problems:
1. Noise induced back into the AC line from one or more of the loads (motors, etc) powered on that circuit. Many newer appliances use motors with electronic commutators in them that induce a lot of electrical noise back into the AC line.
2. Line voltage fluctuations when the loads come on line, possibly caused by undersized wire gauge to the load.
3. Common mode noise, from an external source, such as a nearby radio transmitter. Common mode noise is electrical noise that appears on both the + and - conductors at the same time and at the same amplitude.
The ferrite toroid type filter, used as shown, will only help with #3 above, the case where there is common mode noise. It won't help with #1 or #2. You can get inline AC filters that will help with #1 and #3. AC outlet strips, ones that claim to include surge protection, often have line filtering included. This is also something to try.
Also, if you have a battery backup unit, a UPS, like what are used for computers, that would help with all three issues. It's also likely cheaper that hiring an electrician. If you have one you can spare for a trial, it's worth a try.
I'm a retired electrical engineer, and a Ham Radio operator. It's really depressing to discover how many devices around the house generate a LOT of electrical noise. And the manufacturers don't give a hoot about it.
Mike