Here’s a novel way to take measurements using sound waves with an iPhone. German developer Florian Student’s Acoustic Ruler Pro for iOS will measure distances up to 25 meters by clocking the time delay of emitted sound waves. You can use the app with either a pair of headphones or with another iPhone to measure the distance between the two handsets. [via /.]

Adam Flaherty

Adam Flaherty

I make cool stuff and write about other people making cool stuff on If you have something you think I should see, send me a tip.

  • 零 影月

    The actual process is called “Time Domain Reflectometry” and it’s the same process used in things like cable length testers/break finders and standard ultrasonic distance sensors. This is a pretty impressive implementation.

  • Daniel Kim

    This reminds me of Sonar CE, a Windows CE application that uses the speaker/mic of an iPAQ PDA as a sonar app.  I’ve not had the patience to configure it properly, but user comments seem to imply that it works.

  • Ian Page-Echols

    There’s also a program to do this included with the OLPC XO machines since the Give One Get One’s were sold.

  • Florian Student

    Hello Adam,

    Thanks for writing this article about my app!

    I wanted to let you know that the app is free for the next few days, so may be you can post a follow up to your article?

    Thanks a lot!


    • Bryan

      OK, How do you get it free? The App store want’s $1.99 for it.

    • Bryan

      OK, How do you get it free? The App store wants
      $1.99 for it.