When we buy candles, we generally consider how they look or how they smell. Therefore, most candle makers carve their candles artistically or add scents to the candle waxes (e.g., Red Roses of Jo Malone). However, some candle makers pay attention to a different aspect of candle: wick.
A candle wick is usually a braided cotton that holds the flame of a candle. Wicks can be made of material other than string or cord, such as wood, although they are rare (Wikipedia). Recently, I met a candle maker who was selling wood wick candles. She told me her candles make a relaxing SOUND of burning wood. Since I was fascinated by the sound, I bought her candle without considering how it looked or how it smelled.
Designers and marketers are always searching for latent needs, the needs that consumers do not express verbally. Since a wide variety of shapes and scents are existing in the candle market, candle designers and marketers consider innovating their candles by offering different types of burning sounds.