Aim the speaker at the candle flame and play music to see the candle flame beating, indicating that sound waves can transmit energy;

If you place a homemade windmill above the candle flame, the windmill can When it rotates, it means that the surrounding air is flowing. The flow of air means that the density of the air has changed. This phenomenon shows that the density of the air is related to the temperature.

So the answer is: energy; temperature.