This device is a powerful USB buzzer. You can control both the frequency and the volume. There is even a way to preset simple beeping patterns.
In addition, the Yocto-MaxiBuzzer also features one RGB led, and output for more RGB leds and two analog inputs able to read any resistive sensor such as switches, push buttons, potentiometer, reed contact, photo-transistors, and so on...
Long story short, the Yocto-MaxiBuzzer is the solution you need to definitely get your users attention, no matter the ambient noise.
USB cables and enclosures to be ordered separately.