Sensory science is a scientific method used to “measure, analyze, and interpret human responses to products as perceived through their senses of touch, taste, sight, smell, or sound.” Sensory science is often used to improve existing products or to test people's views on new products, such as the softness of tissues, the crunchiness of an apple variety, or the aroma of air fresheners. It is also used to test the taste and color acceptance of new products, such as purple ketchup, or the sound characteristics of products, as in the crunch of snack foods.