You can really look at it in different ways. One is as Paul and Chris have highlighted. It can be used commercially for marketing and business purposes, but I have a feeling you're looking at it differently?
I studied Sound Art and my dissertation was about how sound and noise has dictated the way we live in our world. An example... Thames Barrier park in London is built with acoustics in mind, the park is raised above traffic to deflect harsh sounds and has fountains at the entrance to mask traffic with white noise. http://static.london.gov.uk/mayor/strategies/noise/docs/urbandes/14thamesbarrierpark.pdf
There are also schools in London which have been redeveloped with noise in mind as well as it being aesthetically pleasing to the eye/brain. There is even proof that it has improved grades. Here's more info on some projects in England which have done this. http://static.london.gov.uk/mayor/strategies/noise/
Acoustics make a massive change to how we perceive our spaces, you only need to walk into a huge cathedral to understand.
You don't have to make sound for it to be sound art/design :)
Also check out some sound sculptures which are purpose made for where they have been placed. Singing, Ringing Tree by Tonkin Liu, http://youtu.be/Ve6PTrlLGOU A sound sculpture that the wind plays. Eerie sounds played by the executed witches that once inhabited the area? :P