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A convenience store in downtown Portland has turned to using a high-pitched, ringing noise to keep homeless people from gathering on the sidewalk in in front of the store.

The 7-Eleven store sits at the intersection of SW Taylor and 4th, on a corner that's regularly occupied by people who appear to be homeless or transient. Up until recently, the store was blasting classical music from its outdoor speakers. Within the last week, that music was replaced with a single piercing note, similar to the noise emitted by a security alarm system.

A 7-Eleven clerk said the noise is meant to keep homeless people away. "The classical music just put them to sleep," the clerk said.

The new tactic is working: The corner outside of 7-Eleven was clear Wednesday afternoon. But it may not be legal.

In Oregon, it's illegal to "make unreasonable noise" with the "intent to cause public inconvenience, annoyance or alarm." A person found guilty of making unreasonable noise could be charged with disorderly conduct in the second degree.

The City of Portland also explicitly forbids this kind of noise. "It is the intent of the City Council to control the level of noise in a manner that promotes the use, value, and enjoyment of property, conduct of business, sleep and repose and reduces unnecessary and excessive sound in the environment," reads an ordinance entered into the city charter in 2001.

Violating this ordinance comes with a penalty of up to $5,000. Several members of the public have contacted the city with complaints about the 7-Eleven noise, as of Wednesday afternoon.

"The business establishment is clearly intending to annoy members of the public who walk by or use the sidewalk in the public space outside their store," said Chris O'Connor, an attorney with Metropolitan Public Defenders.

"I suspect that if you walked into city hall or a police station or sat outside the 7-Eleven manager's house (or the mayor's home) with a speaker at the same volume with the same sound, they'd arrest you for the crime of Disorderly Conduct first and send it to Noise Control later."

7-Eleven did not respond to the Mercury's request for comment.

The building owner, Standard Insurance Company, did explain the noise in a statement to KGW: "Our goal is to protect the safety of our employees, tenants and guests in a location that has been consistently plagued by public drug use and menacing behavior. The sound is a safe tool to help address the problems that have persisted at this location."