The humming sound is not clear! Why is that?

Please check out our video manual on our Facebook page under the tab "Videos" and compare the sounds with your device. White and pink noise may seem strange to us adults, but babies quickly take a liking to at least one of them. For babies, these sounds are soothing as they were surrounded by similar sounds in the womb. If you have any question, please do not hesitate to contact our customer service.