@unseenlarks, I always forget to add windchimes in my Sims' houses, so thanks for telling us that they work indoors! 😎 Like @jpkarlsen said, temperature change (heat) makes air move. This is what makes wind outside. (My mom has indoor windchimes in real life, but it is usually her fan that makes them chime 😃). I used to work in a candle shop where we had a little candle stand that you would light 4 small candles and the heat from these lit candles would turn a windmill set above the candles. This would make 2 angles spin and as they went around they would hit 2 bells and they would chime! 🥳
Of course, if your Sims' house has any Ghosts in it, then for get what me & jpkarlsen just said ... it is clearly the Ghosts that are making the wind chimes move! 😉😃 LOL