I'm amazed WiFi or Bluetooth ever works at all. 8) You can thank Hedy Lamar for that.
Try cleaning the mating surfaces around the door thoroughly. If that doesn't work, consider replacing the microwave or relocating the speaker.
Wifi also has a listen-before-talk model. If it "hears" a microwave running, it thinks it's another station transmitting, and backs off. This feature of the protocol is why long-range networks worked so poorly in the past. If station A can't hear station B, but the AP can hear both of them, then A and B are going to step on each other and the AP won't be able to communicate with either station. This is why the "enterprise" way of deploying networks was to have a ton of access points running at low power; that works well with the listen-before-talk model since the AP likely can't talk to or hear stations that are too far away for the stations in its range to hear.
I don't know if interference robustness still exists in modern standards, as I haven't seen it in a control panel for decades, but it was definitely in 802.11b. I have never tested Bluetooth (or read the standard), but basically... the industry knows this is a problem, and handled it a long time ago. Bluetooth might ignore the problem because it plans on frequency-hopping (away from the microwave) anyway, but like all software, that can easily be bugged.
Now my bluetooth only drops when I'm fairly close to the microwave as it runs. (EDIT: my WiFi, not my Bluetooth)
Yeah, the WiFi is improved. The Bluetooth is the same as it ever was.
I pardon your confusion.
Bluetooths frequency hopping system avoids interference to it and from it by dropping channels with interfernce or other users from the hop set.
So with enough interference, even monentary interference and the hop set reduces and regulatory limits require dropping power from 100-200mW to 25mW. This usually cuts the connection.
I'd post a screenshot from a HackRF-produced waterfall, but I don't have a microwave :). Some wifi controllers can measure energy in the spectrum and can be used to plot a simple waterfall.
Living the dream!
(I'm obviously not an electrical engineer, given this is 10x stuff) If we're talking a 2.45 GHz microwave signal, that's a 12.2 cm wavelength.
But I thought for shielding you only needed to have gaps of <wavelength to null emissions.
Is there some fractional-wavelength propagation, or is my understanding of EM shielding off-base? How are microwaves noisy? E.g. https://physics.stackexchange.com/questions/269672/does-a-fa...
It is "both* dimensions that must be a long way below the wavelength to keep microwaves in.
Instead the door seal uses a technique called a quarter wave choke. It relies on reflecting back any microwaves wanting to escape, and by making incoming and reflected waves perfectly cancel, no power is transmitted.
As OP said, even a small amount of soup dripped onto the seal and your microwaves will all start escaping.
"Propagation" is probably not the right word, but fractional wavelengths can "leak" some amount of field.
Unfortunately there were a few microwaves sold recently in Europe which forgot that design element, and if you pointed at food while cooking it, you would cook your fingers too.
eh... maybe. Don't forget the microwave isn't CW so there's plenty of transmission slots available on the off cycle.