 The Elsberg method was one of the first to determine the threshold value for odorous substances.To date, his olfactometric method is known as one of the best methods to stimulate the threshold of olfactory senses and determine the decaying of the senses once there has been a continuous supply of same smell.Some perfumers stock coffee beans near their displays as it is commonly believed that smelling coffee between perfume testing can limit or reverse olfactory fatigue.