Why Are Leaf Blowers So Loud?

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Why Are Leaf Blowers So Loud

Leaf blowers are an incredibly useful tool. However, the loud noises they make can get pretty annoying. Where does the loudness come from, anyway? Here is a brief explanation that answers the question.

Leaf blowers are usually loud because of the engine, but the noise can also come from the 10-blade fan. Each time a blade running on 6,000 rpm* spins, it makes a popping sound. Multiply this by each blade, and you get a loud, high-pitched, irritating whine.

That explanation was a shortcut, though. If you’ve fallen victim to the cacophony generated by these machines, and want to understand what gives them the power to annoy you and millions of other leaf blower users, continue reading.

What Is a Leaf Blower?

It’s a gardening tool that propels air out of a nozzle to move debris, such as leaves and grass cuttings [1]. Powered by electric or gasoline motors, it’s a self-contained unit with a handheld wand. It comes in these formats:

  • electric corded
  • battery-powered cordless
  • gas-powered backpack
  • gas-powered handheld
  • blower vacuum—sucks in leaves and small twigs and shreds them into a bag
  • wheeled larger units (aka “walk-behinds”)—use a motor for propulsion but must be pushed by hand to be operated

Gasoline leaf blowers traditionally had two-stroke engines, but manufacturers recently introduced four-stroke models to partially address air and sound pollution concerns.

How Loud Do Leaf Blowers Get?

According to Dangerous Decibels, a public health campaign that aims to reduce hearing loss, leaf blower noise from a distance of 50 feet ranges from 64 to 78 decibels (dB).

Blower operators hear 95 to 115 dB. Compare this to typical speech—about 60 dB, a washing machine (75), and a chainsaw (115). Noises 85 dB and above can be harmful to hearing.

You may wonder why people aren’t as bothered by Harley-Davidson motorcycles, which are also very loud. It’s because their engines emit a low-pitched, guttural type of sound as opposed to a high-pitched screech.

Why Are Leaf Blowers So Loud?

We’ve compiled explanations for leaf blower loudness from various experts.

Tech writer Robert Lei leads with this:

“The leaf blower was originally intended as a chemical sprayer in the 1950s. Thus, the bad design. It wasn’t meant to blow leaves.” – Robert Lei

So one reason for the loud design is that it wasn’t initially created to blow leaves at all. It was adapted for this purpose, so the sound wasn’t something the creators were worried about.

Joe Szalko, a fluids and mechatronics professional, explains that there are two sources of leaf blower noise. One is from the sound of air rushing out at maximum velocity—which is when a machine has reached its utmost capacity and can no longer accelerate. This noise is like the blast of air you hear when you drive with windows open.

The second source is from vibrations made by the engine. These are the result of the fuel combustion process combined with the oscillations made by the engine cylinders on the crankshaft. These reverberations go through the entire unit while it is operating.

Muhammad Rabi Bin Mazhar from the National University of Computer and Emerging Sciences attributes leaf blower noise to the process of using high pressure to expel air.

When compressed air is pushed through a narrow tube (the nozzle, in this case), it rapidly expands as it shoots out. This causes the noise. Increased airflow comes from immense power, which creates more noise. This cannot be reduced without compromising on pressure—essential for blowing leaves.

leaf blower works

Chemical engineer Geoffrey Widdison demurs, saying that compromise is possible, but the blower would end up bulkier, heavier, and more expensive. If companies are convinced there’s enough demand for such a product, they’ll mass-produce it. But the common assumption is that very few would pay extra for a clunkier product just because it’s quieter.

Can They Be Made Completely Silent?

Szalko explains that even before the upheaval over gas-powered leaf blowers, engineers had already thought of practical ways to make quieter leaf blowers. It’s just that manufacturers were initially reluctant to implement them due to cost and usability issues.

One method suggested was the replacement of the internal combustion engine with an electric motor. Another recommendation was to put a vibration-dampening material in the backpack.

Both solutions, however, would drastically increase the size, weight, and cost of the backpack unit, which would greatly reduce user mobility. It would also increase costs, which meant less profit per unit. This would make the product undesirable from a corporate perspective.

Richard Li from Macquarie University concurs. He says that the cost of incorporating noise-reduction parts in a leaf blower far outweighs its practicality. Two- or four-stroke motors run leaf blowers—the same ones that operate chainsaws and mowers.

To dampen noise, sound-absorbing materials should encase the main body. This would significantly increase the size of the machine, however, defeating its purpose as a handheld gardening tool.

Eventually, big-name manufacturers like ECHO Incorporated—the company that invented leaf blowers—integrated these procedures in their low-noise models because of community pressure.

They were forced to redesign their original units due to mass complaints from environmental groups and irked victims of leaf blower noise. ECHO’s quietest model generates 65 dB—far from being silent.

Szalko predicts that one day, a company will produce a very quiet leaf blower, one that emits just a whoosh of air. He’s aware that electric models exist, but expect future ones to be significantly quieter.

Right now, though, a silent model isn’t yet possible because current battery technology isn’t sufficient for prolonged use, and contemporary copper coil motors are too heavy. He says we need to wait for more sophisticated materials to be readily available in electric motors first before theories can be applied and upgrades implemented.

Elon Musk announced last year that he was going to release a silent leaf blower. Many were underwhelmed, citing existing electric leaf blowers, lawnmowers, and string trimmers. A year later and a totally silent leaf blower hasn’t yet materialized.

How Leaf Blowers Contribute to Noise Pollution

How Leaf Blowers Contribute to Noise Pollution

Noisy environments can cause both mental and physical health complications, such as auditory conditions, sleep disorders, cardiovascular problems, and stress. The Centers for Disease Control and Prevention claim the noise leaf blowers generate can lead to serious hearing problems.

Some gas-powered leaf blowers emit between 80 and 85 dB while running. Most cheap or mid-priced units can expose users to up to 112 dB. (A plane taking off generates 105 dB.) The National Institute of Occupational Safety and Health recognizes that exposure to sounds over 85 dB causes hearing loss.

The low-frequency sound leaf blowers emit fades slowly over long distances or through building walls. Even from far away, a conventional blower is still over the 55 dB limit considered safe by the World Health Organization.

Acoustics experts auditory neuroscientist Mitchell Sutter and psychoacoustician [2] Michael Hecker say blower noise is especially irritating because of its particular pitch, changing amplitude, and the hearer’s lack of control.

How Manufacturers Have Quieted Leaf Blowers

To comply with the 1995 and 1999 California regulations for noise and air pollution, leaf blower manufacturers modified their engines.

This is what ECHO did to reduce the noise of their leaf blowers. They looked at spectrographs of all the sounds coming out of their blowers and eliminated the peak sounds. (A spectrograph is an apparatus for photographing or recording images or the distribution of sound components.)

They accomplished this with an array of modifications. They switched the mufflers with alternatives that weakened the sound volume. They modified the blower fan and scroll to eradicate the high-pitched squeal. They revamped the blower tubes and nozzles to adjust the air intake and output.

They introduced the four-stroke engine because the air pulsing through the carburetor cannon of the traditional two-stroke engine was very noisy. They also redesigned the cooling fins on the engines to prevent them from vibrating in tandem with the pulsing of the cylinder. They used acoustic foam to muffle noise.

Finally, they enclosed the engine in a sound-deadening, vibration-resistant plastic to contain the vibrations. ECHO claims they’ve reduced the sound pressure in their low-noise models by 75% (from 77 dB to 65 dB).

Battery-Operated Leaf Blowers Are Even Quieter

In the mid-2000s, to assuage critics further, manufacturers introduced the cordless leaf blower powered by a nickel-cadmium battery.

Another more powerful energy source with a longer run time followed—the lithium-ion battery. Most cordless leaf blowers today run on this. Battery-powered blowers operate at an estimated 70% noise reduction compared to their predecessors.

Some think battery-powered leaf blowers are quiet because they have electric motors. ECHO claims this isn’t true because their air impellers** are not sound-attenuated (weakened in force or effect).

Battery-powered electric blowers aren’t any quieter than gas models because their design generates a “siren” type of sound. They’re emission-free, though, and can operate for about 20 minutes before needing a recharge.

Where Are They Banned?

In 2018, the US had over 11 million leaf blowers annoying even more people. Most US cities don’t have legislation that deals specifically with leaf blower noise, so existing noise ordinances aren’t enforceable for these devices.

Many others, however, restrict the decibels (between 65 dB and 75 dB) of leaf blowers and the time of day they can be used. Gas-powered models are targeted as they are the loudest. Some restrictions only apply to residential areas, while others are citywide.

Many places where these rules exist are quiet communities that just want to minimize noise pollution. But a few larger cities passed these laws to keep the peace among residents.

Incessant leaf blower noise has caused many disagreements and altercations in neighborhoods that previously didn’t experience disorderly conduct. This is why some rules are the result of citizen petitions.

The states that regulate leaf blower use are California, Colorado, Connecticut, Florida, Illinois, Maryland, Massachusetts, Michigan, New Hampshire, New Jersey, New York, North Carolina, Oregon, Texas, and Washington.

Areas that have completely banned the use of gas-powered leaf blowers include some European cities, three cities in Colorado, seven in Illinois, one in New Jersey, one in Massachusetts, 19 in California, and many in New York.

Some places take these rules and regulations more seriously than others. Los Angeles has been banning gas blowers since 1998, yet landscapers and gardeners continue to use them. The newer electric leaf blowers aren’t illegal, though. The penalty for violation is a fine of $20 to $100, depending on the city and state.

Leaf Blowers vs Brooms

Detractors say, “Why not just use a broom? It’s silent.” True, but they’re disregarding the time saved by using a mechanical tool instead of manual means. To illustrate the time difference between using a leaf blower and a broom, ECHO documented the comparison with videos.

They pitted a broom against their PB-760LNT model ($550) in removing leaves from a 210-ft long driveway and a 5,540-sq ft courtyard. Using a broom took almost an hour compared to operating a leaf blower, which took only 6.5 minutes.

Tips for Buying a Low-Noise Leaf Blower

If, after everything you’ve learned about leaf blowers, you still want to purchase one, choose a reduced-noise model, at least. Check the American National Standards Institute (ANSI) noise rating printed on the packaging.

No ANSI decibel rating means it’s quite loud. ECHO quiet leaf blowers come in six variants: PB-250LN, PB-255LN, PB-265LN, PB-460LN, PB-760LNH, and PB-760LNT. Buy direct from them or from Amazon, where units start at $170.

It’s important to choose a leaf blower that can be easily switched between vacuum mode and blower mode.

You should also be aware of restrictions regarding leaf blower use. Many municipalities, for example, limit leaf blower noise to no more than 65 dB. You don’t want to violate local rules or ordinances without realizing it.

To find out if your city has a ban or restriction on leaf blower use, call your city clerk’s office or do an Internet search with keywords like “What cities ban leaf blowers?” or “(the name of your city) + leaf blower.”

Formats

Leaf blowers are available in heavy and lightweight formats. To know which one is appropriate, first find out the chore level of your yard or garden. How much cleanup do you require, and how often do you do it? What is the size of the area that needs to be maintained?

Next, choose the type from the list we’ve outlined above. We recommend handheld or corded models for small gardens and backpack or wheeled/walk-behind units for larger ones.

Bags and Speeds

Most leaf blowers have collection bags for leaves and other debris. Choose less bulky ones to make discarding easier. Consider the size of your garden when choosing the speed of your blower. The ratings for airspeed (miles per hour) and airflow volume (cubic feet per minute) give you an idea of a blower’s power.

Batteries

Choose the battery according to the size of your garden. A large battery means more charging time. Keep this in mind when you consider the area to be cleaned.

You may want to buy an extra battery to tide you over while the main one is charging, especially if you do a lot of vacuuming in addition to blowing. You need only one battery for a smaller garden.

Look for a blower’s amp-hour ratings and battery voltage to assess its power. Battery power is measured in voltage. Large batteries have a power capacity of 40 to 58 volts.

The power level of normal or smaller batteries is up to 20 volts. Calculate the capacity by the running time. The greater the capacity, the longer the running time. A small garden needs around 1.5 to 2.0 battery capacity. Medium to large yards need higher powered batteries.

Don’t worry about sacrificing power if you choose an electric or battery-operated leaf blower. With advances in technology, many modern cordless leaf blowers are as powerful as their gas counterparts.

Quiet Alternatives to Leaf Blowers

Say you’re sold on leaf blowers, then you find out that your city has banned all of them. What now? Don’t reach for the rake yet. Try lawn sweepers. You can choose from two variants:

  • Manual: The push lawn sweeper is for regular home and garden chores. The tow-behind type is for professionals with a riding lawn mower or ATV (all-terrain vehicle).
  • Powered: The low-noise battery-powered sweeper is for cleaning pavements, parking lots, and other hard surfaces.

The Flip Side

We’d like this report to be balanced, so we’re including the point of view of leaf blower operators.

In an ABC report, interviewers asked gardener Jesus Mercado how he would respond to leaf blower noise complaints. He said that if he cleared leaves by hand, it would take him hours and cost homeowners a lot more money. “I get some headaches sometimes when I use (a blower), but what can I do? It’s my job,” he said.

ECHO explains that operators generally have to run leaf blowers at maximum power. Otherwise, leaves won’t move. But it is now recommending that users adjust blower settings according to the task at hand. For instance, if you’re moving only grass clippings, you don’t have to run the blower at full power. You can always throttle it down.

Silence Is Golden

…and we’re still hankering for it. Now that we know why leaf blowers are loud, do we blame the manufacturers? They have complied with regulations while still plying their trade. Legislation has come to the rescue of leaf blower noise victims. Isn’t this enough?

Unless a totally silent creation emerges, protesters will continue to rant. Years from now, one just might. Meanwhile, those bothered by the noise of current models (and we mean the quiet ones) just have to invest in soundproofing… and wait for Elon Musk to get his act together.

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* The measurement unit ‘rpm’ stands for revolutions per minute.

** An impeller is the rotating part of a centrifugal pump, compressor, or other machine designed to move a fluid by rotation. [New Oxford American Dictionary]

[2] Psychoacoustics is the branch of science studying the psychological responses associated with sound (including noise, speech, and music).

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Dominic

Through several years of research and experience, I can say with confidence that I have acquired substantial expertise in the field of soundproofing. I only put out information which I know is genuine and is backed with research. Read More About Me..

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