What's the best Android app for falling asleep to calming sounds without ads interrupting?

Sleep Sounds is an app designed specifically for users who struggle with sleep initiation and prefer a consistent, uninterrupted auditory environment. The app's primary strength lies in its approach to minimizing disruptions; while it is ad-supported, the audio advertisements typically play only upon opening the app, not during the active playback of sleep sounds. This allows for a soundscape that can run from minutes to hours without commercial breaks. Key features include a diverse library of over 50 high-quality ambient sounds, ranging from steady white noise and fan sounds to nature recordings like rainstorms and forest streams. A particularly useful function is the sound mixer, which lets users layer multiple sounds (e.g., combining 'Campfire' with 'Distant Thunder') to create a personalized backdrop. The built-in sleep timer automatically stops playback after a set duration, which conserves battery and prevents sounds from playing all night. However, some reviews indicate that while the ad model is less intrusive than most, the free version does lack certain premium sounds and features. For individuals seeking a straightforward, reliable tool to mask disruptive noises and cue relaxation, Sleep Sounds provides a simple and effective solution.