CPAP seems to vary in pressure but it's not in auto mode

[DBBCPAP]

I'm new to my CPAP after only 4 weeks of use.  I don't understand what I'm feeling - hope you folks can help.  My set pressure is 7cm.  When I first startup the CPAP at night, each rush of inhalation makes a significant noise - enough so my wife can easily hear it.  And enough so that I usually use the ramp feature to let me go to sleep without fixating on the noise.  But when I wake in the middle of the night, it seems that the noise and therefore the pressure is very much less than it is when first starting.  My wife could not even hear me breathing last night.  I'm not talking about the first couple of breaths when the machine is trying to figure out what's going on - instead after it reaches steady state.  From Sleepyhead, I can see that the pressure is always 7 (except for when I use the ramp feature which is set to 15 minutes) so it is not in auto mode for sure.  I have Flex set to #2.  I don't believe that in either case there are leaks that would cause the noise.  Is the variation in noise normal?

Thanks for your help.

[Walla Walla]

You will have some sound when the machine is switching between inhale and exhale due to flex. That might be what your hearing.