AudioSet by Google - A massive dataset of manually annotated audio events
Power Nap App - Best napping timer with relaxing sleep sounds
Note Tracks - Annotated notes for audio content
Meditato - Meditation and sound sleep to make your life better
AudioNotes - Easily record and share audio messages from your Mac menubar
Mildd: Sounds to Sleep - Mildd is an app made for you to connect with nature, providing the deepest relaxation, reducing the level of stress and anxiety and helping to combat insomnia.