[lordmathis]

I started designing and building a voice assistant for myself and then realized that the only time I'd find it useful would be during cooking to set timers. But a loud extractor fan would be running making the voice recognition very difficult.

[jlokier]

An extractor fan is the kind of consistent noise that good signal processing and voice recognition ought to be able to strip out, especially if using a dispersed mic array. Even if your voice is much quieter (to your human ears) than the fan. It's a channel separation problem.