A sound trademark is a non-conventional trademark where sound is used to perform the trademark function of uniquely identifying the commercial origin of products or services.
Sometimes referred to as "sonic branding."
A Trademark is a word, phrase, symbol or design, or a combination thereof that identifies and distinguishes the source of the goods of one party from those of others.
A Servicemark is the same as a trademark, except that it identifies and distinguishes the source of a service rather than a product.
Trademarks can be registered with various individual states, the USPTO, and other countries.
With trademarks, the phrase "Likelihood of Confusion" refers to the idea that you would not want two things to have the same trademark as to confuse the buyer about the origin of the goods or service.