NORWAY – Officials at military bases around the Northeast said Friday that their jets were not the cause of a large sonic boom-like noise heard in parts of Androscoggin and Oxford counties Thursday morning.

The Oxford County Regional Communications Center in Paris received several calls around 9 a.m. Thursday after the loud noise, but emergency responders were not able to determine a source. A dispatcher at the center said the noise may have been a sonic boom.

Lt. Col. Lloyd Goodrow, public affairs officer with the Vermont Air National Guard, said that while F-16 jets with the 158th Fighter Wing do train over Maine, they did not take off until 8:45 a.m. Thursday and were not flying over Maine that day.

The fighters are based in Burlington, Vt.

Goodrow said F-18 jets from a Virginia naval base have been training out of Burlington and were flying near Kennebunkport on Thursday, but would have been at a high enough altitude that a sonic boom wouldn’t have been audible.

Goodrow said that while pilots sometimes do sonic runs, they are done at altitude or over the ocean.

“No military aviator intends to break the sound barrier over populated areas,” he said.

Goodrow said fighters sometimes inadvertently break the sound barrier during exercises, and that atmospheric conditions can allow for the sonic boom to carry for a long distance.

Evan Lagasse, public affairs specialist for the Otis Air National Guard Base in Massachusetts, said the 102nd Fighter Wing was transferred to the 102nd Intelligence Wing earlier this year. The base’s F-15 aircraft were dispersed to other locations.

Capt. Mary Harrington, public affairs officer for the 104th Fighter Wing based in Westfield, Mass., said a flight of three jets was exercising Thursday off Atlantic City, N.J., but no planes from the base were over Maine.

David McKivergan, a SAD 43 board member from Rumford, said he saw three jets fly over his residence between 8:45 a.m. and 9:30 a.m. Thursday. He said the jets remained in the air for 45 minutes, but he did not hear a sonic boom.

McKivergan said such flights have been occurring, though not on a regular basis, for the past two to three years.

John James, public affairs officer for the Brunswick Naval Air Station, said northern Maine and New Hampshire are partially covered by two low-level flying zones that have been approved by the Federal Aviation Administration for military flights.

James said the speed of sound is 761 miles per hour at sea level in standard temperature and pressure, and can be affected by temperature, pressure and humidity.

A sonic boom occurs when conical pressure waves off the front and rear of an aircraft are supercompressed, causing a sudden rise in pressure and a shock wave which causes the booming noise.

James said the sound doesn’t necessarily dissipate with altitude, as it can be heard from aircraft traveling at 70,000 feet. James said no supersonic aircraft are based at Brunswick.