Acoustic Ruler Pro by Florian Student (Universal)
Released: Nov 1, 2011
Version: 4.4
Size: 3 MB
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Ranking - Utilities (iPhone)

Ranking - Utilities (iPad)

Acoustic Ruler Pro

Florian Student
[ This app may no longer be available for download ]

[Please also check out my app Sonalarm, the first sleep cycle alarm clock app that works from your bedside table with NO additional hardware!] Wouldn't it be amazing to have a ruler in your pocket all the time? Well now you can! Measure distances of up to 25 meters (82 feet) with two devices or up to 1.10 meters with one device and headphones.
Click below on "Florian Student Web Site" or open to watch two videos demonstrating the app.

Acoustic Ruler Pro has been featured on Cult of Mac, Techcrunch, GIZMODO, lifehacker, and MAKEZine.

The app works by clocking the time delay of the emitted sound waves. There are two different operation modes: a single device operation (with headphones) and a dual device mode for measuring the distance *between* two devices. Read below to find out which modes work on your iOS device.

Single device (headphone) mode:

This mode works on the iPhone 3GS (and newer), iPod Touch 3rd Generation (and newer) and on all iPads. You either need one of those devices and headphones with a mic or headphones without a mic and a iOS device with a built-in mic (excluding the iPod Touch 3rd Generation). The resolution in this mode is 1mm or 1/10 of an inch, depending on the unit system you have selected.

Dual device mode:

For this mode you need two compatible iOS devices. These are: iPhone 3GS (and newer), iPod Touch 4th Generation and all iPads. One device has to be started as the master device, and the other as the reflector device. The measurement is started on the master device, by pressing the “Measure” button. The reflector device then sends back the chirp of the master which displays the measurement result. The resolution in this mode is 1cm or 1/2 of an inch.

When you first start the program, it will guide you through the easy calibration steps with text and illustrations explaining what to do. Please recalibrate when you are getting wrong measurements.

The app lets you set the air temperature as an additional calibration. This is important, because the speed of sound varies considerably with temperature, affecting the precision of the measurements.

You can switch between displaying the measurement in feet/inches and meters/centimeters. Accordingly, the air temperature will either be set in degrees fahrenheit or celsius.

Since the app works by sending and receiving sound, you’ll obviously get the best results when using it in an environment that is not too loud.

Starting with version 4.2 of the app, the measured latency (delay) is also displayed. Double-tap the display of the distance to swap the locations where delay and distance are displayed. This feature was added because a couple of users of the app thought it could be useful to measure latencies in their audio systems. In the dual-device mode the displayed delay corresponds to the delay from one device to the other (i.e. half of the totally measured, round-trip delay).

If there are any problems with my app, please let me know by using the contact form on my blog. I will do what I can to get it working perfectly on your device. Customer satisfaction is very important to me.

Follow @acoustic_ruler on Twitter to stay up to date with the newest developments, or to report any problems you may have.

What's new in version 4.4
[Please also check out my app Sonalarm, the first sleep cycle alarm clock app that works from your bedside table with NO additional hardware!]
* Fixes for iOS 8
* Adapted to iPhone 6 and iPhone 6 Plus
Our verdict: Ok
  • + Acoustic Ruler Pro is an ok, 3.5-star app.
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