It boggles the mind, the things that one can claim to “own” — not to mention the notion that there are bureaucracies that are willing to offer up this kind of “property” to claimants: San Francisco Journal – A Quack Sets Off a Legal Squabble in San Francisco (pdf)

But if a new duck in town, if you will, has its way, Mr. Scannell’s quacking days could be over. Last month, a rival company, Ride the Ducks, filed suit in Federal District Court here to stop Bay Quackers from using quacking devices on its tours.

At issue is a “sound mark,” the auditory equivalent of a trademark, which Ride the Ducks says it holds on a quack created by a yellow bill-shaped kazoo (called a Wacky Quacker) and which it says Bay Quackers has violated by using a similar kazoo that creates an identical quack.

“If you blew theirs and ours, you wouldn’t hear any difference,” said Bob Salmon, vice president of marketing and sales for Ride the Ducks, whose company has been using its kazoo for more than a decade. “It’s a very important part of our product. We’re very interactive with people on the street, and the way that we interact is using our Wacky Quackers.”

[…] “We don’t have a problem with competition, even direct competition,” Mr. Salmon said. “But we have a problem with them infringing on our trademark.”

The “sound mark” serial number is #75686528 (registration number #2484276); filed April 14, 1999, registered September 4, 2001. (You can look it up on the USPTO.GOV website) The description of the mark is as follows:

The mark consists of a quacking noise made by tour guides and tour participants by use of duck call devices throughout various portions of the tours.