Page 12 - Summer2017
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 Benjamin M. Faber
277 South 2035 West Lehi, Utah 84043 USA
Acoustical Measurements with Smartphones: Possibilities and Limitations
A smartphone-based sound level meter or analyzer may or may not replace your expensive, precision instruments.
With an estimated 1.4 billion units sold globally in 2016 (GfK, 2016), smartphones constitute a ubiquitous mobile computing device, capable of performance com- parable to that of high-end desktop computers of just a few years ago. Beyond their undeniably widespread adoption, smartphones are mediacentric devices, complete with microphones, cameras, wireless communications, and large touch screens. For those with a smartphone in their pocket, and particularly those inter- ested in acoustics, this raises several questions such as, “Now that I have a micro- phone connected to a computer in my pocket, what can I measure with it?” and, “How good could the measurements be?”
The Signal Path
To answer such questions regarding the use of smartphones in acoustics, it be- comes important to understand the path through which an acoustic signal must pass to be accounted for in any kind of measurement or analysis software. Al- though the signal path must obviously include some kind of transducer, such as a microphone or loudspeaker, there are other elements to consider, such as analog and digital electronics, device firmware, and operating system (OS) software. The focus of the smartphone on media creation and consumption leads to a relatively mature handling of audio signals. Existing smartphone-based solutions for acous- tical measurement and analysis rely on this well-established audio signal path to provide convenience and low cost. Figure 1 illustrates the most common audio connections for a smartphone.
Getting Signals Into the Device
The most obvious portion of the audio signal path may be the built-in microphone
 Figure 1. Common audio input and output connections for smartphones and other mobile devices.
 10 | Acoustics Today | Summer 2017 | volume 13, issue 2 ©2017 Acoustical Society of America. All rights reserved.

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