Hum

Developer’s description of app: Create custom sound effects reminiscent of early scifi movies and television shows.

This app has 10 different frequencies of tones. You can move the slider to change each tone frequency. I think this is a great concept and could lead to some awesome apps. I have found out that if the app sounds staticy or weird you just need to restart your iPhone. After I restarted mine it sounded great!! You can even play more than one tone at a time! So, install away!!

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