What is the function of a blow dryer’s cool shot button?

The function of a blow dryer’s cool shot button is primarily to set the hairstyle by cooling the hair. When styling hair, the use of heat helps to mold and shape it, but a cool shot helps to lock that style in place. Cool air causes the hair strands to contract, which can help in setting curls or waves created while styling. This can enhance the longevity of the style and provide a polished look.

The other options pertain to different actions that a blow dryer can perform but are not related to the purpose of the cool shot feature. Increasing drying speed involves maintaining a constant flow of hot air, while reducing noise levels usually requires different design features in the blow dryer itself. Lastly, adding volume typically involves the use of heat combined with styling techniques, rather than the cool shot function, which serves to set rather than add volume.