Emit Particles when Area turns into specific color

Hello!
I am looking to make a piano synesthesia video. (I would post a URL but I am not allowed to
)
In these videos, there is a virtual keyboard in which a key changes color when it is getting hit. It also emits particles vertically when the virtual key is being pressed.
I understand how to make particles and change their basic properties in fusion from all the tutorials out there, but I was wondering if anyone can fill me in on how to make the particles emit automatically once the piano key is hit (and the color in that area changes) as in the videos? I know that I can probably do it manually using keyframes but I would rather have it automatically change as it would save me a lot of time.
Thanks ahead of time for anyone that looks into this. If something is unclear let me know.
I am looking to make a piano synesthesia video. (I would post a URL but I am not allowed to

In these videos, there is a virtual keyboard in which a key changes color when it is getting hit. It also emits particles vertically when the virtual key is being pressed.
I understand how to make particles and change their basic properties in fusion from all the tutorials out there, but I was wondering if anyone can fill me in on how to make the particles emit automatically once the piano key is hit (and the color in that area changes) as in the videos? I know that I can probably do it manually using keyframes but I would rather have it automatically change as it would save me a lot of time.
Thanks ahead of time for anyone that looks into this. If something is unclear let me know.
