Nightmare wake-up. It can automatically detect the ambient volume. When the volume reaches the preset DB value, the mobile phone will automatically alarm and start the ringing tone to notify the owner and record the sound. The resident notification service can detect and record in the background. The recording record can be viewed and closed at any time. It is suitable for people with nightmares, people troubled by nightmares, or other people who need to be reminded of the volume in decibels.