Dealing with noise conducted through the hose ...

Many CPAPers are bothered by the noise of their machine. Much of the time, the noise that they find so bothersome is the conducted noise coming through the hose or coming directly from the mattress---if either the xPAP machine is actually touching the bed or if the table the xPAP is on is touching the bed. Conducted noise can magnify the sound of your breathing as it affects the pressurized air being blown into your mask by the machine as well as the sounds the machine makes all by itself. Moving the hose even slightly can help with this problem.

And what is conducted noise? All solids are capable of transmitting sound waves. It's just that we're usually not attached to a solid that is carrying sound waves in an environment that allows the conducted noise to be particularly noticeable to us. The sound waves the hose are carrying, by the way, include the sound of your breathing as well as the sounds the machine itself is making. And every inhale/exhale you make affects the flow of the air in the hose, which affects the sound of the flow of the air ....

In general, conducted noise that you notice is from sound waves that are transmitted through solid substances (the hose, your pillows, covers, body) to your head and skull, and directly into your inner ear; thus conducted noise completely avoids the usual transmission route for sound through the outer ear through the ear drum, into the middle ear, through the three small bones in the middle ear and into the inner ear. And because conducted noise gets to your inner ear without going through the outer ear at all, using earplugs to dampen or block noise can actually intensify the annoying and irritating conducted noise. That's because the earplugs fit into your outer ear and they only block the NON-conducted noise. Hence all that's left is the conducted noise, so you hear it loud and clear in all its irritating glory.

And how do you deal with conducted noise from the hose? First, try moving the hose: If it's lying on your pillow or actually touching your head---particularly the area around the back of your ears, try to move your head and the hose to minimize the contact between the hose and the pillow and your head. The hose touching the pillow is the usual number one suspect in conducted noise from the hose. (That's also part of why the special CPAP pillows with the cutouts for the mask not only help stabilize the mask and reduce leaks, but also may help with conducted noise issues.)

A simpler solution may be to give the conducted noise a bit of more pleasant competition to distract your conscious mind from the noise. In general irritating noises (be they real or nasty tinnitus) are often easier to ignore in the presence of a more pleasant auditory stimulus---such as a cd of nature sounds, other pleasant "white noise" or even quiet soft music. And note: You do NOT need to have the volume of the music/nature sounds/etc on high enough to drown the conducted noise out---no it's actually more effective in the long run if the pleasant sound is at a comfortable (quiet) level for sleeping that's just barely loud enough to give the conducted noise competition for your attention. That's all it takes to get your mind off the conducted noise--competition from a more pleasant auditory stimulus that you'd rather listen to. Then the conducted noise fades into the background and you don't notice it. The same trick works for my tinnitus by the way.

Because my husband doesn't object to it (in fact he tells me he enjoys it), I've dealt with the conducted noise issue myself by leaving my iHome on all night repeatedly looping through a very long Gregorian chant playlist playing at a reasonably quiet volume. I can't stand headphones or earplugs and I was noticing that I kept waking up when the iHome was turning itself OFF when I was using its Sleep feature. So it's better for my sleep to just leave the Gregorian chants playing all night long. And the Gregorian chant keeps my mind off the conducted noise from the hose unless I've got a migraine or tension headache brewing. But that's another issue all together.

What the heck is a cmH2O and how much additional pressure does a CPAP really generate?

CPAP pressure is measured in units called cmH2O.  One cmH2O is the amount of (additional) air pressure needed to raise a column of water by one centimeter.  The cmH2O unit is basically a metric version of "inches of mercury" that we use in the US to measure the barometric pressure for weather forecasting.  And just how much additional pressure does 1 cmH2O represent in terms that are meaningful to an average American?  Well, if we go to Unit Converters and scroll way far down the list, we can convert 1cm H2O into (about) 0.029 inches of mercury.  Since standard CPAP pressures range from 4 cmH20 to 20 cmH2O, that means they range from 0.116 to 0.58 inches of mercury.

Standard atmospheric pressure varies from day to day, but typical values are in the 28 to 30 inches of mercury range.  Right now (August 14, 2011 at 8:20am), Weather Underground is reporting the air pressure in Buffalo, NY as 29.76 inches.  When a typical storm front comes through, the air pressure drops anywhere from 0.25 to 1.5 inches of mercury.  Some people are really sensitive to these changes in atmospheric pressure and get "pressure" or "weather" headaches or lots of joint pain.  But most people don't notice them very much.  At the maximum CPAP pressure of 20cmH2O, the machine is ADDING about 6/10 of an "inch" of additional pressure on top of the current atmospheric pressure---about as great of a pressure difference between a typical raining day and a typical sunny day.