Are different people able to sense different stimuli? We all have the same five senses right? Even though that is true many of our senses have a natural variation and some lose their ability over time.
The sense of hearing or audition is a sense that loses its ability to perceive certain stimuli. "Teen Buzz" is a product to take advantage of this phenomena. It is basically a loud and annoying buzz that is emitted at a frequency of approximately 17.4 kHz. At this frequency the sound is only really heard by people under the age of 25. Its intended purpose is to be projected around businesses in order to stop loitering, vandalism, and drug use. I tested myself and my 19-year old friend, we both could hear the 17.4 kHz buzz. It was loud and almost hurt to listen to. It would definitely be a good deterrent.
All senses also follow a natural variation when it comes to ability. Just like height or weight a person's ability to sense stimuli will be different compared to almost anyone else. Just as there are super tall people, there are also people who have a heightened ability to sense things. Olfaction, or the sense of smell, follows this and a person with a heightened sense of smell could "smell the beans in Brazil", as the proverbial phrase goes.
As with the other senses certain animals have a sense of smell that is many times better than even the best human's. The silvertip Grizzly Bear (pictured below) has the best sense of smell of all animals. Their sense of smell is 7 times stronger than a Bloodhound's which are renowned for their ability to detect and follow scents.