Amazon's delivery drones are so loud they are like a 'giant hive of bees'

• Amazon faces pushback from residents in Texas, where it's testing its delivery drone program.
• Residents are complaining about the level of noise as Amazon seeks to expand the project.
• Amazon's Prime Air drone program wants to increase flights in the area from 200 to 469 a day.

Amazon's delivery drone robots once seemed like a futuristic joke. But now, as the company seeks federal approval to expand its drone program, it's facing a fundamental challenge: They're too loud.

Drones are generally loud machinery. Anyone who has tried to relax on a beach while someone flies their drone can relate.

Australians have for years complained about the noise level from Alphabet-owned drones used by Wing, a food delivery service in the area. And even locals in Nepal say the drones Sherpas plan to start using to clean up trash from Mount Everest sound like "a swarm of bees."

John Case, an orthodontist from College Station, Texas, where Amazon's delivery drone experiment is taking place, told CNBC that he recently encountered an Amazon delivery drone that "sounds like a giant hive of bees."

"You know it's coming because it's pretty loud," Case said.

Amazon is seeking approval from the Federal Aviation Administration to expand its drone delivery operation beyond College Station into Tolleson, Arizona, according to CNBC.

College Station's city manager, Bryan Woods, ran tests on one Amazon drone and found it emitted noise in the range of 47 to 61 decibels, according to the report. Decibel levels of 40 to 65 are similar to a typical suburban area at night, a household refrigerator, or a business office, according to the decibel level comparison chart from Yale Environmental Health and Safety .

In May, Amazon submitted a proposal to the administration to increase deliveries in College Station from 200 to 469 flights a day. Shortly after, College Station Mayor John Nichols wrote in a letter that residents were getting fed up with the noise.

"Since locating in College Station, residents in neighborhoods adjacent to Prime Air's facility have expressed concern to the City Council regarding drone noise levels, particularly during take-off and landing, as well as in some delivery operations," Nichols wrote, according to CNBC.

Amazon and Mayor Nichols did not immediately return Business Insider's request for comment.

Amazon said in a statement to CNBC that it is "proud of the thousands of deliveries we've made and the hundreds of customers we deliver to" through its Prime Air drone program.

"We appreciate the community of College Station and take local feedback into account wherever possible when making operational decisions for Prime Air," the statement said.