quiet generator - high noise imageThe Quietest Generator?

So you’re looking for a quiet generator?  What about the quietest inverter generator?  This article will answer that question, but the answer cannot give you the absolute brand and model, because of the many factors that affect the sound produced and how it is measured.  So let’s start this explanation up and see how much noise we can make (pun intended).

The image above is meant to be humorous.  Sorry if it’s not.  The truth is, work safety organizations actually limit the amount of time that you can work in high noise areas.

The unfortunate thing is, some generators are so noisy that they WOULD have a limit to working with them.

There is one absolute statement we can make: inverter generators are the quiet generators.  These generators are quieter than an equally powered standard generator.  This is determined by the mechanics of how they work and from what materials they are made.  You can read about the differences between standard and inverters on this site.  But if quiet is what you must have, then look no farther than inverter generators.

Why it’s Hard to Answer the Question

The absolute way to tell which is the quietest is to make all other factors equal.  That is, put them side by side and start them up one at a time.  By equal factors, I mean same surroundings, same thing plugged in (or nothing plugged in), standing the same distance away, EVERYTHING.  You can use a decibel (dB) meter if you need an actual measurement.

Chances are, the dB reading will differ from the one reported by the manufacturer.  Because conditions MATTER.

When you review different generators, the company that makes them will rate how noisy (or silent) they are based on their decibel meter.  I’ll get into just what that means shortly.  Decibels are not that hard to understand, but when you understand them, you then have to consider how a company measures the sound.

Beware, decibels is a measurement only.  And is pretty subjective to a consumer when looking at the sound required for generator power.  Are you concerned with what is louder than another?  Or are you asking, what is noisy vs. what is annoying? 

Compare to temperature measurement in degrees.  What might be just right for you, may be too hot or cold for your spouse.  The steady sound of a generator may be too loud for me, but not too loud for you, regardless of the actual decibel measurement.  One may chug while another hums loudly.  For example, the 65 decibel range may be annoying to some, but normal conversation is rated at 60 decibels.  The rock concert measurement of 110 decibels may be great for you, but will drive Aunt Margaret from the building!

concert-and-loud-music

You want to buy a quiet portable generator, so the noise that it makes is important to you.  But so should be the other factors like cost per watt produced, fuel efficiency, environmental friendliness, portability, etc.  I mentioned that inverters are the more quiet portable generator, but there is no such thing as a silent generator (unless you include solar powered generators in the conversation).  However, an inverter can cost substantially more than a standard generator of the same watt output.

The Quiet Generator

For example the Yamaha ef2000is is an inverter, which is considered a super quiet generator which costs close to $1000, whereas the standard generator, All Power APG3014 costs less than $300.  Both are rated at 1600 running watts and have similar features.  But the Yamaha is rated at 52 to 60 dB and the All Power is rated at 65 dB.  (both are reviewed on this site).  The decibel rating of inverters can fluctuate based on how much load is being put on it.  A standard generator mostly runs at the same speed.

the quietest generator is the yamaha inverter

Yamaha ef2000is inverter generator

quietest generator - All Power APG3014

All Power APG3014 generator

 

 

 

 

 

 

 

 

 

Remember, as the power output (wattage) goes up, so does the decibels.  This is easily explained because to get more power output, you need a larger engine.  For example there is a Yamaha inverter model that is half as powerful at 900 running watts.  And its decibel reading is 47 – 57dB, because it has a smaller engine.  As you can see, it is a whisper quiet generator compared to the All Power model.

In general, as inverter generators increase from 1000 watts to 6000 watts output, their dB level increases from 47 – 57 dB to 58 – 64 dB.  Conversely standard generator dB’s increase from 65 dB to 75 dB over the same power output range.  The difference between 65 and 75 means that 75 is twice as loud as 65 according to the decibel scale.

OK, so we know if quiet is the deciding factor, then get an inverter generator.  If you want a standard generator due to cost or whatever reason, know that certain brands tend to operate more quietly than others.  For example the 7 horsepower (HP) WEN 56352 is reported to run at 67 dB, whereas the 7HP Durostar ds4000s is reported to run at  69 dB.

Now you ask, 2 dB?  Is that all?  Doesn’t seem like much.  Actually it is, and if you feel like understanding the science of it, read on.

Sound and the Decibel Scale

The sound that we hear is energy, and travels in sound waves.  For example when you pluck a guitar string, you hear a sound.  What is happening is the vibration of the string is affecting the air molecules around it.  These air molecules in turn affect the ones around it, and on and on until the air molecules in your ear are affected.  Your ears pick up the sound wave pattern so you hear the pluck of the guitar string.

If you pluck the string harder, more energy (increased amplitude of vibration) is displaced and finally you hear the louder noise.  Simple, right?

There is some fancy mathematical equations having to do with energy and area that give sound “intensity”.  It is this intensity that is measured on a scale measured in decibels.

A decibel reading of zero does not mean the absence of sound.  It means it is the lowest sound that the human ear is capable of hearing.  It is called the threshold of hearing.

Here’s where you must throw out your linear thinking.  That is, a decibel reading of 100 is not twice as loud as a reading of 50.  Let me explain.

Decibel scales are logarithmic.  Missed the day in math class where that word is explained?  Well simply put, for every increase in 10 dB’s is 10 times more.  So from 1 to 10, 10dB is 10 times more than 1dB.  But from 1dB to 20dB, 20 is 100 times more than 1.  30 is 1,000 times more than 1, and so on.

These differences are measured in “intensity” NOT “loudness” as loudness is a subjective measurement.  So 20 dB is not 100 times “louder” than 1dB.  Confused?  It is generally accepted that 6-10dB is “twice” as loud.  So a generator at 60 dB is “twice as loud” as one with a reading of 50dB.

Also, decibels are not additive.  That is, if you ran two 60dB generators side by side, you would NOT get a reading of 120dB.  Confused yet?

Here are some examples of common source sounds and their approximate decibel intensity level.

Common Sound SourceDecibel (dB) Intensity Level
Threshold of Hearing                          0 dB
Rustling Leaves                                10 dB
Whisper                                           20 dB
Library                                              40 dB
Normal Conversation                        60 dB
Street Traffic                                     70 dB
Vacuum Cleaner                               80 dB
Front Row Rock Concert                 110 dB
Threshold of Pain                            130 dB
Perforation of Ear Drum                   160 dB

Here’s a fun fact:  On the logarithmic nature of the decibel scale, the difference between the threshold of hearing and the threshold of pain is 130 dB, but is actually one billion times more intense and 13-15 times “louder”.

Portable generators range from 47 dB from a small 1000 watt inverter to 76 dB for a 15 HP 10,000 watt standard generator.  So the quietest generator based on this is the 1000 watt inverter, but does that make it the right choice for you?  Is it enough power?  Can you afford it?

dB Ratings – The Readings Could be Misleading

It depends on how the readings are taken by the manufacturers.

Here’s another fun fact:  If you double the distance you are from the sound source, the intensity is quartered.  So if the intensity is 16 at 1 meter away, the intensity is 4 at 2 meters away.

Now if I’m measuring the decibels for my company, the result would depend on how far away I take the measurement, right?  So I might take the reading from farther away.  The standard is measurement at a distance of 7 meters.  But how do we know that this is being followed?

Here’s a couple more fun facts:  Measuring decibels is further complicated by the density of the air between you and the sound source.  And also by the absorption of the sound by the ground and physical surroundings between you and the sound source.  And the measuring device also picks up the ambient noise.  For example, the same generator noise taken next to a freeway might be 80 dB, whereas if measured in a quiet open field, that same generator may measure 77 dB.  Remember decibels are not additive.

I guess what I’m saying here is that you should take the reported dB rating given by a generator brand with a grain of salt.

The generalities are that inverter generators are the quietest generators.  There is a quietest inverter generator, but you have to compare similar wattage.  The Noise level increases as you increase the engine size.  You can check out the inverter comparison table.

Some muffler systems work better at reducing noise output.  So ask yourself, “What is your annoyance threshold”?  You will then find the quietest generator for you.

The simple answer to which is the quietest portable generator?  Choose the portable generator that will serve your needs first, because unless your hearing is quite acute, the noise level within the brands is not a factor, once you decide between the inverter and the standard.

If necessary, you can operate the unit further away.  You can block it with sound absorbing materials.  You can wear headphones and listen to your favorite concerto.  Just don’t crank up the music too high.  Or you’ll be listening to 90 dB!  OUCH!

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