Quieter Than A Whisper At An Incredible 33 SEER

When it comes to ductless mini split systems, the topic of conversation generally bounces from efficiency to aesthetics and rarely makes the long journey towards the topic of how quiet they are.

When you think about it and look at the specifications, ductless mini split systems are incredibly quiet! The minimal amount of noise pollution that these systems produce is rather incredible, but before we take a look at some numbers and make a few comparisons, let us take a look at what a decibel is and how they are perceived.
-The following is an excerpt from the Engineering Toolbox-
Decibels (dB)
“The ear has the remarkable ability to handle an enormous range of sound levels. In order to express levels of sound meaningfully in numbers that are more manageable, a logarithmic scale is used, rather than a linear one. This scale is the decibel scale.
What is a decibel?

Zero decibels (0 dB) is the quietest sound audible to a healthy human ear. From there, every increase of 3 dB represents a doubling of sound intensity, or acoustic power.”
Loudness and Sound Intensity (Power)
“The relative loudness that we perceive is a subjective psychological phenomenon, not something that can be objectively measured. Most of us perceive one sound to be twice as loud as another one when they are about 10 dB apart; for instance, a 60-dB air conditioner will sound twice as loud as a 50-dB refrigerator. Yet that 10-dB difference represents a tenfold increase in intensity. A 70-dB dishwasher will sound about four times as loud as the 50-dB refrigerator, but in terms of acoustic intensity, the sound it makes is 100 times as powerful.
Here’s another way of looking at it: If the sound from one typewriter registers 60 dB, then ten typewriters clacking away would register 70 dB (not 600 dB!), and they would sound only twice as loud as one typewriter. You would need 100 typewriters to reach a noise level of 80 dB, and together they would sound only four times as loud as a single typewriter.”
Now that we are all a bit more informed about the decibel, let us look at how ductless mini split systems stack up against rival noise making technology & nature.
Before we begin a few more facts:
• The threshold of pain in regards to noise levels is about 125dB
• At around 100 dB regular exposure of more than 1 minute poses the risk of permanent hearing loss.
• The threshold of normal hearing starts at about 1000-4000 kHz
Our first example will be of a Fujitsu 9RLS3 system like the one seen here. The indoor unit on the “quiet” setting will produce 23 dB or in other words, quieter than a whisper and not too much louder than the sound of your breathing.
The outdoor unit for this 9RLS3 system operates with all the enormity of a mouse at a mere 42 dB and if this sounds like a lot to you, 42 dB is around the same level as the hum of your refrigerator and this unit is outside.
Let us compare these numbers to a PTAC unit like what you would find in a hotel room. First of all, dB numbers are hard to find as they’re not widely advertised – because they’re loud. If you’ve ever stayed in a hotel room, you’ll be well acquainted at the level of noise these systems produce.
The following is a list of things that the outdoor unit of a mini split system is quieter than:
• A quiet office
• A normal conversation
• A vacuum cleaner
• Dishwasher
• Your shower
• A Howitzer cannon firing (Well, this one is a given)

The impressiveness of these mini split systems becomes more astounding with every new model. With incredible efficiency, SEER ratings (like 33.0), capacities and convenience – The level at which they produce these may be the most impressive of all.