With the wide array of sensors available to Arduino users, it is easy to find solutions to many problems or help enhance situations for various subjects. One simple and interesting example of this has been shown by Instructables user "station420" who has made a device to help the visually-impaired.
Although only in the protoype stage, it uses an ultrasonic distance sensor whose values are processed by an Arduino and converted to sound with a piezo buzzer. This setup is then places on a hat and worn by the intended user - who is then alerted to the distance between the direction in which they're looking and an object by the buzzer, for example:
It certainly shows promise, and once finished and placed in a small enclosure could be a quite useful device. To learn how to make your own, visit the project page. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
If you're interested in working with making sounds and tunes for various reasons or knock detection, we have a neat little SOUND: sound and buzzer module:
It can be used as a noise-maker driven by your microcontroller for audible feedback of events, and it can also be used as a knock-detector input to sense events and react to them. Includes a built-in 1M resistor to allow the piezo element to detect shocks. For more information and to order, please visit the product page here.