Crunchy describes food that makes an audible crisp sound when bitten and chewed — a texture defined as much by acoustics as by mouthfeel. The sound comes from brittle structures fracturing under the teeth: the dry starch matrix of a crisp, the sugar glass of toffee, the cell walls of a fresh apple or raw carrot. Food scientists link perceived crunchiness to moisture content, cell turgor, and the force needed to break the structure, and they measure it with texture analysers that record the jagged force peaks of fracture. Consumers read crunchiness as a signal of freshness and quality in produce and of correct frying or baking in snacks and coatings. Because the sensation fades as foods absorb moisture, packaging that protects crispness — moisture barriers, nitrogen flushing — is a major part of snack manufacture.