M-Series whining noise

[JimIllinois]

My M-Series auto aflex has begun a high frequency whining, which is annoying to listen to at sleepy-time. It's just loud enough that my wife can hear it on her side of the bed.

The whine is "load-dependent," by which I mean it changes in intensity and frequency depending on whether I am inhaling, exhaling, or pausing between the two. If I practiced, maybe I could make it sing a song...

I have a suspicion what the problem is, but I'd like to hear if anyone else is familiar with this.

Thanks!

[Wulfman]

My M-Series auto aflex has begun a high frequency whining, which is annoying to listen to at sleepy-time. It's just loud enough that my wife can hear it on her side of the bed.

The whine is "load-dependent," by which I mean it changes in intensity and frequency depending on whether I am inhaling, exhaling, or pausing between the two. If I practiced, maybe I could make it sing a song...

I have a suspicion what the problem is, but I'd like to hear if anyone else is familiar with this.

Thanks!

My guess is that there's an "issue" with the Flex mechanism/motor/fan.
Which Flex option and setting are you using? Try switching to another option or turn it off entirely and see what it sounds like.

Den

[Rustyolddude]

It's normal for the M-series and takes a bit to get used to. Even the Whisper Cap doesnt help much.

[boston]

mine did this for awhile, but it went away after some time, and yes it was annoying

[katcw]

Have you changed your filters recently? Perhaps something has gotten into the machine.

[cinco777]

The whine is "load-dependent," by which I mean it changes in intensity and frequency depending on whether I am inhaling, exhaling, or pausing between the two.

Both my M-Series APAP units (primary and backup) exhibit the same sound as you describe. The sound remains whether the unit is operating in APAP mode (range of pressures), C-FLEX, A-FLEX, CPAP (same constant pressure), or with a Whisper Cap. I have a table fan on a nightstand next to the bed and run it at medium speed. The fan's "white noise" does alleviate most (but not all) of the whining sound. Because of the whining sound which affects my falling asleep (even with my table fan on), I will not be purchasing my next machine(s) from Respironics.

I have observed that the whining sound is not as annoying with certain masks. However, the masks with the less pronounced "whining" are not the ones (Flexifit 431 & 432) that provide me the most comfort, stability, and lowest leak rate.

[ken woodland]

one month on c-flex nose is hard to deal with. Hose or tube is what is making the nose on mine. The air whirling down the flex hose is tubulure sound . Working on how to stop the sound. Help me if you can.

[JimIllinois]

Here's my take on why it happens... It's sort of a technical workshop.

I work in an industry that uses electric motors controlled by electronics that vary the motor speed. I would imagine that the CPAP machines use the same technology. The electronics create a "manufactured" bit of power, rather than the usual generated power we all get from the power company. The electronically created power is not so nice and smooth, and this causes some stress and vibration in the motor. It's often a whining noise. Some of the noise comes from the coiled wires in the motor, and some from the bearings that allow the shaft (and in this case the fan blade) to spin.

I expect that the mechanical construction of a cpap is not so tough and shock resistant. The bearings are probably sensitive to shocks, as you would get if you bumped the thing around on an airplane, or even had to gate check it as I did a few weeks ago.

So, my theory is that the bearings have been beat up some, and are now more sensitive to the rough electrical power sent by the electronics, causing them to resonate a ton louder than they used to. Just a theory.

A few weeks ago, there was no whine, just the sound of blown air. Now it's very loud.

[under-the-radar]

Your assumption ref the frequency drive theory could be correct. Now in my case I have not traveled or handled the machine much since I received it two weeks ago yet I have the same problem. And no its not the mask or the hose!! In fact, I have removed the mask completely and just running my hand very so slightly across the flex hose opening I can easily duplicate this sound. ( Note: I tried a spare hose new and the problem persisted.) The environment is clean and as dust free as I can get it so with only two weeks worth of use its not the filter though I did remove it momentarily to see if it made at difference-it did not. Thinking that the electronic devices in the room could be an issue I turned everyone of them off only to still be awakened by this high pitch noise. The noise starts at approx 4 cm H20, goes away a bit above 5.5 cm H2O. I am sending it back and purchasing another ( apex auto) hoping to have better luck with a new machine. Still the engineer in me would love to know exactly what the problem is. I will continue to give this more thought and should I find a solution will post same.

[tooter]

Your assumption ref the frequency drive theory could be correct. Now in my case I have not traveled or handled the machine much since I received it two weeks ago yet I have the same problem. And no its not the mask or the hose!! In fact, I have removed the mask completely and just running my hand very so slightly across the flex hose opening I can easily duplicate this sound. ( Note: I tried a spare hose new and the problem persisted.) The environment is clean and as dust free as I can get it so with only two weeks worth of use its not the filter though I did remove it momentarily to see if it made at difference-it did not. Thinking that the electronic devices in the room could be an issue I turned everyone of them off only to still be awakened by this high pitch noise. The noise starts at approx 4 cm H20, goes away a bit above 5.5 cm H2O. I am sending it back and purchasing another ( apex auto) hoping to have better luck with a new machine. Still the engineer in me would love to know exactly what the problem is. I will continue to give this more thought and should I find a solution will post same.

Interesting, but I hope you realize you are responding to an 8 year old post