One of the questions we are most frequently asked is, “How
noisy is the generator?”
Unfortunately, there isn’t an easy answer to this question
as everyone throughout history has interpreted noise differently,
just like art and music… That is, until 1928 when workers
at Bell Telephone Labs scientifically quantified noise levels as
a convenient way to express power losses in telephone lines, and
termed it decibel (dB) (literally, one tenth of a bel), in honor
of founder Alexander Graham Bell. Bell scientists defined decibel
as a unit for expressing the relative difference in power between
acoustic or electric signals, equal to ten times the common logarithm
of the ratio of the two levels.
For those who understood this definition, please click here on Tech
Noise Info and skip the remainder of this section.
For those who, like most of us, do not have a clue about Bell’s
definition, we decided to go back to the good old days when everyone
interpreted noise as they pleased, i.e., I can’t hear anything
(1dB); whisper quiet (15dB); library quiet (40dB); normal conversation
(50dB); noisy machinery (80dB); annoying lawnmower or leaf blower
(95dB); rock concert enraging (110dB); and back to I can’t
hear anything (anymore! 120dB+). Towards that end, we have recorded
the noise levels of a variety of generators with a variety of options.
As a reference to more familiar noises, we also recorded common
equipment like an air conditioner, a lawnmower, as well as the 2004
Cicadas (next update in 2021).
So please click on the tabs below to listen to the sound levels
for yourself keeping in mind that, contrary to the suggestion of
our sales department, lowering the volume on your speakers will
not reduce the noise level of the generators!
An important note which needs clarification is the log scale of
dB level ratios, meaning that every 3dB increase is equivalent to
doubling the noise level, and that every 10dB increase is equivalent
to a tenfold increase in the noise level. For example, 63dB and
70dB noise levels are equal to double and ten times the noise level
of a 60dB noise level, respectively.
The most significant factors that determine the noise that we hear
are, by order of importance, the type and level of sound-attenuation
(enclosures and natural barriers), the distance from the source,
and the size, type and specifications of the engine. A generator
with a custom sound attenuated enclosure will reduce by about 20
times the noise level of the same generator with a standard enclosure
(say from 72dB down to 59dB), and by about 1,000 times the noise
level of the same generator without any enclosure (say from 89dB
down to 59dB). Doubling the distance from the source will result
in halving of the noise level (say from 72dB down to 69dB); factors
that also influence the noise we hear are the existing ambient noise,
the positioning of the generator, and the type of base and ground.
In summary, we would like to note one last interesting fact while
addressing the original question at the top of the page. Every single
day of the year, regardless of the weather or of other conditions,
at least one of our customers is without utility power, and their
generator is actively providing emergency back-up. Over the years,
out of our hundreds of residential customers, we have only had one
noise complaint from a customer, following a period when our generators
had been running continuously for over a week. Accordingly, we can
safely state that all our generators emit an acceptable noise level,
and some are actually quieter than your AC and meet strict county
noise ordinances (typically 65dB during the day and 55 dB at night
as measured at the property line).
a final note , it is important to keep in mind that all standby
systems operate (and produce noise) on a temporary basis only when
utility power is unavailable.