How to get into sound test (repost and for all models)

[Potchiitchi]

First, press a + c and hold them down and reset your Tamagotchi and then it will go into sound test! I hope this helped you.

 

[Bentobuff]

First, press a + c and hold them down and reset your Tamagotchi and then it will go into sound test! I hope this helped you.

Which models is this for? I know the post title says ALL, but I personally find this a bit difficult to believe. Which models have you tested this on? Which ones have you not?
What does this sound test do? Does it vary from unit to unit? If so, how?

 

[Potchiitchi]

Which models is this for? I know the post title says ALL, but I personally find this a bit difficult to believe. Which models have you tested this on? Which ones have you not?
What does this sound test do? Does it vary from unit to unit? If so, how?

I have done it on my R2D2 Tama, 2017 Og Tama rerelease, and Pac-Man Tama

Which models is this for? I know the post title says ALL, but I personally find this a bit difficult to believe. Which models have you tested this on? Which ones have you not?
What does this sound test do? Does it vary from unit to unit? If so, how?

And the different versions have different sounds if they are different licensed ones, and sound test lets you listen to the sounds

Which models is this for? I know the post title says ALL, but I personally find this a bit difficult to believe. Which models have you tested this on? Which ones have you not?
What does this sound test do? Does it vary from unit to unit? If so, how?

I haven’t tested on every other but the ones I listed before