I feel that my window air conditioners are too noisy. Actually, there
is nothing wrong with the air conditioners; I am just too sensitive to
noise especially when I need to go to sleep. I am thinking of replacing
them with some kind of split system that has the noisy compressor
placed outdoor. Because of the fact that my house is not suitable for
running ductwork (no attic), I probably prefer a ductless split system
that has a blower indoor. Now the question is:

How quiet those ductless split system is as
comparing to a window air conditioner?

I would really hate to spend a lot of money getting a ductless split
system installed and then discover that the it (the blower) is not much
quieter than the window air conditioner that it has replaced.

My questions a

- The spec of one of the most quiet mini-split system says that its
indoor unit generates 40-db or something. According to www.Oneida.com,
40-db is like the noise from a normal conversation. Honestly, I don't
really know how noisy a "normal conversation" is as applying to an air
conditioner. But surely this doesn't sound very good. What's people
opinion on this based on their personal experience with a ductless
split system? Do they find the noise level to be acceptable for
sleeping? How much difference of its noise as comparing to the noise
from air flowing through an air register of a central air conditioner
(with ductwork)?

- How a noise level was rated? Are they all rated 3-ft away from the
air conditioner?

- What's the common noise level of a modern window air conditioner
being sold within the last 2 years or so? Something like low-50-db or
high-60-db? I don't have a sound-meter available (at least not yet); I
cannot measure the noise level of my existing window air conditioners.

Thanks in advance for any info.

Jay Chan