A Guide to Gauging Generator Noise Levels

Portable power generators are one of our main sources of electricity in the event of a power outage or interruption. They are extremely useful and exceedingly convenient for use in homes, offices and small businesses, and are within the reach of the ordinary budget. One deciding factor in choosing a portable genset is the amount of noise produced by a unit, depending on what one considers soft or loud, and portable power generators can be very loud, indeed.

How does one determine whether generator noise emissions fall within the limits comfortably tolerated by humans? First, you need to isolate where the noise actually comes from. Portable power generators normally emit noise from two separate sources: its engine and its exhaust. In many cases, noise level data provided by portable genset manufacturers do not factor in the noise created by a unit’s exhaust.

The volume of noise created by a generator is usually measured in terms of decibels, and decibels are the standard unit of measurement for the intensity of sound. There is a decibel scale that ranges from total silence (0 decibels) to the sound of a gunshot (140 decibels), and this intensity is affected by the number of sources of the sound and the distance from it.

That said, the more generators you have in operation, the louder the noise produced. If you take a look at the decibel levels of generator noise using a typical 60-decibel portable power generator and compare it with normal noises heard everyday, you’ll be able to get a clearer reading of the kind of generator noise level a portable power source can produce:

Sound Decibel Level Power Generator
Quiet Whisper (closed room) 30 decibels  
Conversation (3-5 feet away) 60 decibels 60-decibel generator (20 feet away)

Moving a portable genset closer by double the number of feet increases the noise by 6 decibels:

Sound Decibel Level Power Generator
Dial tone (telephone) 70 - 80 decibels 60-decibel generator (10 feet away)
City traffic (from inside closed car) 85 decibels 60-decibel generator (5 feet away)

Conversely, moving a portable power generator away by double the distance reduces the noise level by 6 decibels. Distance plays a big role in the lowness or loudness of generator noise. On the other hand, more than one generator within the same hearing distance automatically doubles the decibel levels:

Sound Decibel Level Power Generator
Loud rock concert 115-120 decibels two 60-decibel generators (20 feet away)
Pain threshold 125 decibels two 60-decibel generators (10 feet away)
Jet engine (100 feet away) 130-140 decibels two 6-decibel generators (5 feet away)
Damage to hearing tissue 180 decibels  

It is also interesting to note that a person can incur hearing loss from sustained generator noise levels of between 90 to 95 decibels, which is equivalent to trucks in traffic, or a subway train going 200 miles per hour.

When searching for a portable backup power source, it is important to look into acoustical dampening methods to reduce the noise level and prevent hearing loss from sustained noise. A lot of generator manufacturers and third-party retailers in the market today offer solutions, such as silencer devices and enclosures, to attenuate generator noise emanating from its engines and exhaust systems. A solid wall barrier separating a portable genset from main areas where people congregate can likewise lower decibel levels considerably.

References:
http://www.gcaudio.com/resources/howtos/loudness.html
http://www.campinglife.com/output.cfm?id=1047547
http://www.generatornoise.com/