I loved these kind of 'background noise' apps when I was a student, they cut out the noise on the street and keep you focused without being distracting like music. Also contains alarms and countdowns so you can drift off to sleep yourself, or send a baby to sleep (personally I used a hoover for that, probably cost more than 10p). Promotional blurb below.

APPLICATION FEATURES
• 40+ perfectly looped sounds with additional free sounds from the White Noise Market
• Record and loop new sounds with total ease
• Background audio support so you can use other apps while listening
• Create new soundscapes by mixing multiple noises together with support for adjusting volume, balance, and pitch of each individual sound in the mix.
• Full screen digital clock with multiple colors and brightness controls makes it the perfect companion for any nightstand
• Advanced alarm and timer system that slowly fades audio in and out so you awake naturally feeling more refreshed
• On-screen media player and volume controls with swipe gesture support for navigating sound collection
• Star favorite sounds and mixes in the sound catalog for quick access using the Favorite view
• Designed to work on all Android-based phones and tablets
• Advanced Settings let you prevent interruptions such as notifications, tweak buffer size for optimal playback, adjust sound volume, balance, pitch, custom alarm snooze times, and more. All the pro tools and settings you need for better sleep.
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