From a bit of quick research, it sounds like there are a few options - especially if the Android tablet is always powered as having the microphone always checking for noise levels might consume a decent amount of battery - one of those options being to use the Noise Level state from the AutoVoice Tasker plugin to trigger the action and then use SharpTools for Android to interact with SmartThings…
AutoVoice has a sound level (noise) context. Not calibrated to a db scale, but the trigger can be set.
It’s under new profile → state → plugin → AutoVoice
…you have to enable the AutoVoice Noise Service so that it starts monitoring for noise
…The issue with setting it to -90 and it being a State Profile is that the State won’t trigger again until the condition becomes untrue, then true again. And if you have the sensitivity set to maximum sensitivity (-90) it’s probably going to be “always on” just from ambient noise in the room and it won’t ‘reset’ to trigger the Profile again.
…There’s an “Invert” checkbox when you are configuring the plugin in the Profile? If it’s doing the opposite of what you want, see if this box is checked. If so un-check it. If it isn’t, try selecting it. One of those two might be able to correct it.
Edit: I haven’t tried it, but it looks like there’s also a Sound Detector plugin for Tasker that might work as well.