The only white noise machine that is truly adjustable. Tone and volume controls allow you to create the perfect white noise for your environment and four distinct white noise tones to help you fall asleep and stay asleep. Perfect for bedside or portable use. Advanced white noise therapy offers 4 distinct tones to help you fall asleep and stay asleep: Soothe: Like a gentle rain, this tone has the lightest pitch—gently easing your mind Mask: Designed to mask external distractions including noisy neighbors and highway traffic Relax: Modulated to disrupt interfering room noise, such as snoring Calm: The deepest of all tones. Perfect for tinnitus sufferers & small children Tone control allows you to manually adjust the tone of the white noise to best fit your needs.