It happens several times each day.
by Brian Frank
The noise of a helicopter is difficult to describe. The thwap, thwap can be so loud to wake you up in the middle of the night or force you to close the front door in the middle of a summer hot spell.
Helicopter noise can emanate from a few different operations, but the most ubiquitous helicopters are the patrols of the Los Angeles Police Department – the largest police helicopter unit in the country. Though we don’t know how close or how far away the reason for the air support is, it takes a mental toll on me and my neighbors because it means something bad is happening somewhere nearby.
What is helicopter sound? Why does it seem more intrusive than other noises? Is this an issue or an annoyance? What are the rules and regulations over helicopters? Should the rules apply to the helicopters that are there to keep us safe? These are the questions that I think about when helicopters keep me awake at night.
Some call it blade slap, or blade-vortex interaction – the pulsating deep bass and high pitch sound “created when a rotor blade hits the wake left behind from the blade in front of it.”
The San Francisco Department of Public Health stated an increase of just 3 decibels doubles the acoustical energy emitted. In San Francisco, officials estimate that 1 in 6 are at risk for health problems due to annoyance, anxiety and sleep problems because of traffic noise.
Traffic noise, though more persistent, is about the same volume as a helicopter flying around 500 feet, the lower end of the altitude the Los Angeles Police Department regularly flies.
In addition to hearing loss at the extreme and a loss of concentration at the least, noise exposure in a workplace or classroom setting can cause behavioral changes and problems with self-confidence and irritation, according to the World Health Organization.
Noise also can affect mental health and has been implicated in producing stress-related health effects such as strokes, ulcers, heart disease and high blood pressure, according to the “Noise Effects Handbook,” published in 1979 by the U.S. Environmental Protection Agency.
So though noise may be an annoyance, there are serious consequences.
Eight different studies in the 1970s found that the annoyance created by a helicopter does not equate with the decibels it registers. The chopper’s unique sound causes people to rate its sound level as much as 10 decibels higher than it registers, doubling the noise impact.
The Los Angeles County Department of Public Health agrees that 10 decibels is significant, according to Robert Vasquez, who monitors such things for the County.
Officials will visit to your home and set up noise monitoring equipment outside if a resident has a noise complaint. If anything is making a sound above 50 decibels or 45 at night for more than 30 minutes in an hour, they will make it stop. Vasquez almost always solves the problem without ever issuing a citation. He just works with the person or business creating the disturbance.
They do this about 40 times a year.
“Excessive annoying noise may be detrimental to public health,” Vasquez said. “We have set standards to address excessive noise.”
There’s only a five decibel difference between what’s allowed at night and day because “5 decibels is significant,” Vasquez said.
A sound level of 75 decibels – almost as loud as an alarm clock two feet away – will cause 37 percent of the population to be highly annoyed and a conversation would be unintelligible. At that level, noise is likely to be the most important of all adverse aspects of the community environment, according to the EPA’s noise handbook.
The LAPD’s AStar helicopter, an intermediate-sized craft, produces about 87 decibels at 500 feet. The LAPD usually flies between 500 and 700 feet.
Vasquez said the complaints from county residents are often for air conditioners, public address systems, fisherman at the harbor.
Of course, the county gets a lot of complaints about jets and helicopters. But those, Vasquez said, are “under the FAA.”
People think that Burbank is all fine, and that the airport is the cause. BS. Noise pollution is serious here. How about seven times a day? About 5 or 6 times a day, those are police. – A Burbank resident*
This series on helicopter noise is brought to you by Spot.Us, with contributing support from the California Endowment and KCET. Eddie North-Hager runs a news & social network for a number of L.A. neighborhoods, including Leimert Park.
* Starred comments are taken from a survey taken in May 2011 distributed to members of LeimertParkBeat.com, EchoParkOnline.com and SanPedroNewsPilot.com. It was also sent out on Twitter specifically through @Venice311, @CoCoSouthLA and @HubCityLivin. At the time of publication 57 surveys were completed. To see the survey, click here.
To take a survey about helicopter noise, Click here.