AMITIAE - Tuesday 22 October 2013

Checking Sound Levels with iOS: Failures and Successes

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By Graham K. Rogers

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Over the last few days I have had some limited success with apps from Siemens. The company has more than 50 iOS apps that use the company name and while many are for specific services that Siemens provides, some have wider access.

Of the apps that Siemens puts out, I tried a couple that test hearing in different ways: the useful Siemens Hearing Test and the French language Test @udio. Both are easy to use and provide results that offer useful indications.

Siemens Decibellmeter

decibels Thinking I was on a roll, I tried a third app from Siemens that seemed perfect for the city environment of Bangkok: Siemens Decibellenmeter. Although this uses Dutch as its language, the app is simple enough when first examined, except for one major flaw.

When the app opened there was a clear screen with three distinct sections below the company name: a panel to display a result; a scale as sound levels rise and fall; and a Start/Stop button. At the bottom are two buttons: the first links to the Siemens Netherlands site, while the second shows a panel with some expected sound levels (e.g. Rockconcert - 110 dB).

The first time the Start button is pressed, the user is asked permission for the app to access the microphone. But then nothing happens. There is no movement on the sound scale, nor any recorded figure displayed. I did notice that a red bar appeared at the top of the screen, but this was so fast (and there was no text) that I do not know if this was a good thing or not.

I restarted the iPhone, deleted the app, deleted it from iTunes, reinstalled several times; and then I repeated this on the iPad (where it displays in the limited x1 and x2 modes).

Into the trash with this one.

dB Volume

decibels Not wishing to admit defeat I had a look through iTunes and found a couple of free apps that seemed to serve the same purpose, except that they worked. The first was dB Volume.

After the nice looking opening screen, the app opens with a straight forward vertical display of sound pressure levels. There are four settings options, each of which affects the display. Beside the vertical bar there is a numerical display of the output.

The options are:

  • Response time mode, for impulse, slow or fast
  • Weighting functions
  • Peak hold function (the highest figure is shown as a number)
  • Leq - a way to describe sound levels that vary over time (Gracey)

The app is simple to use and gives understandable output.

Decibel 10th

decibels The third free app I tried is Decibel 10th. The display here is a little more complex as it uses the concept of an analog meter as its main display, but no more difficult to use than dB Volume.

There are actually four output methods with this app. At the top is a graph form that runs continuously. When this is pressed, a panel appears with three options: Send data to email, Clear graph, and close. Pressing Clear graph will remove the history. The email arrives with a zipped file that contains data in CSV format (Comma Separated Value). Unfortunately, the zip file did not seem to have any data inside.

The main section in the centre of the screen has a simple to read analog display that shows blue for safe levels of sound, and orange for higher levels, beginning around 75 dB.

Below this is a digital display with three figures: current (which fluctuates with sound levels), Max, and Peak. Pressing the Max figure allows this to be reset if required.

Where the meter needle pivots, there is a button, marked with two yellow bars. When this is pressed, the current figure (meter and numerical) is frozen, so a reading at a specific time can be assessed.

Right at the top, there is a display that indicates the type of sound that is being sensed: Quiet Street, Avg Automobile, Loud singing). Also in the top bar is an information (i) icon which allows settings to be changed. This includes a calibration slider.

Three apps for checking sound levels which gave me varying degrees of success. There are several others available in the App Store.

Graham K. Rogers teaches at the Faculty of Engineering, Mahidol University in Thailand where he is also Assistant Dean. He wrote in the Bangkok Post, Database supplement on IT subjects. For the last seven years of Database he wrote a column on Apple and Macs.



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