PARTICIPLES NOT CHECKED – Please help urgently?

I just don't understand the past participles. No matter how hard I try, everyone says something different: On YouTube, one person says "I laughed " (laughed: past participle), then another says "The switched-off cell phone" (switched-off: past participle). ChatGPT says "switched-off" = past participle, but the first participle is, for example, "lachend," isn't it? I…

Subwoofer with active control?

There are many companies that manufacture subwoofers and many subwoofer models. But unfortunately there are hardly any models (anymore) with active feedback based on an accelerometer. It's clear that such active feedback is difficult and therefore expensive at high frequencies. But at frequencies below 200 Hz, it shouldn't be a technical problem. And since most…