The noise level of a CPAP machine will vary depending on the model and brand of the machine. Usually, CPAP machines produce a low-level, steady hum, similar to the sound of a fan or air conditioner. Most CPAP machines have noise levels between 30 and 60 decibels. This is considered a moderate noise level, but it can still be uncomfortable to some users, especially if they are sensitive to sound. However, many newer models of CPAP machines are designed to be quieter than older models.