We spend a lot of time watching and listening to our smartphones and tablets. The younger you are the more likely you are to turn to them for watching a movie or TV show instead of an actual TV. For a lot of us it is our primary source of music with our own content or streaming services. Very rarely when new phones or tablets are announced does a company place any emphasis on the quality of the audio.

Display quality also used to receive very little attention. As more and more people reported on the display performance, more companies started to take notice. Now benefits like “Full sRGB gamut” or “dE < 3” are touted on new products. So now we are going to introduce a new set of testing for smart phones and tablets, audio performance.

To do this right we went to the same company that all the manufacturers go to: Audio Precision. Based out of Beaverton, OR, Audio Precision has been producing the best audio test equipment out there for over 25 years now. From two channel analog roots they now also test multichannel analog, HDMI, Optical, Coaxial, and even Bluetooth. Their products offer resolution that no one else can, which is why you will find them in the test and production rooms of almost any company.

Just recently they introduced a brand new set of audio tests for Android devices. Combined with one of their audio analyzers, it allows us to provide performance measurements beyond what has been possible before. Using an Audio Precision APx582 analyzer we set out to analyze a selection of Android phones to see what performance difference we can find. More phones and tablets will follow as these tests can be run.

The Test Platform

The test platform is the Audio Precision APx series of audio analyzers. For this initial set of tests I used an APx 582 model, which has two analog outputs and 8 channels of analog inputs. The outputs are not necessary as all of the test tones are provided by Audio Precision for playback on the devices. For each set of tests we can add a load, simulated or real, to see how the device handles more demanding headphones. For this article I am sticking with only a set of the updated Apple Earbuds. They are probably the most common headphone out there and easy to acquire to duplicate testing. For future tests the other loads will be AKG K701 headphones and Grado SR60 headphones. Both models are popular, and I happen to own them.

There are a few main tests we are going to use for all these reviews. Those key tests are maximum output level, Total Harmonic Distortion + Noise (THD+N), Frequency Response, Dynamic Range (as defined by AES17), and Crosstalk. These tests are the exact same ones that manufacturers will be running to verify their products. Most of these tests will be run at maximum output levels. Most amplifiers perform best at close to their maximum levels, as the residual noise compared to the signal decreases, and so that is what they are typically tested at.

We might add more tests as we decide they are relevant to our testing. I will also attempt to go back and fill in as much data as possible from previously reviewed devices as time permits. Now to look at the tests and see our results for our initial set of phones.

THD+N
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  • Impulses - Monday, December 9, 2013 - link

    All great suggestions IMO. Reply
  • haukionkannel - Tuesday, December 10, 2013 - link

    I allso agree. Maximum volume level is not the same as guality, you have to find measures that are relevant in normal listening volumes. They vary yeas and depends a lot of used headphones. So I would allso recommended of using headphones with different impedanses! One pair of high impedance hifi headphones. One pair of low impedance hifi headphones and one pair of high guality (but commonly used) low impedance headphones.
    Otherwise it would be like testing 780 triple sli setup using 320p resolution mini monitor...
    (Well actually not likely because phones have not been very high guality sound sourses, but I think that you got the point.) Good sound qaulity is important factor to me, so I am very eager to hear more (pun inteded ;-) about these test and allso the results!
    Reply
  • DaveSimmons - Monday, December 9, 2013 - link

    Thanks for doing this. When my 120 GB iPod dies I'll probably replace it with a smartphone or tablet, so this will help me choose which one to use. Reply
  • estarkey7 - Monday, December 9, 2013 - link

    As others have stated, and I will reiterate, Only Anandtech! Bravo!

    I would love to see a similar article comparing HD Voice for the carriers. I know that test may be more difficult to conduct, but ever since Sprint hyped their HD Voice and didn't deliver, I'd like to see some real engineers do the topic justice.
    Reply
  • hlovatt - Monday, December 9, 2013 - link

    Congratulations AnandTech, yet again you show the rest of the review industry what they should be doing. Keep up the good work and it should be fascinating to see the full set of results. Thanks. Reply
  • willis936 - Monday, December 9, 2013 - link

    Is there any comment on the practical issue of noise at low volumes? Noise floor testing is uncommon but phones are noisy and are typically listened to with sensitive buds. Who cares it'd the dynamic range is 100dB if you never turn the volume up past 30%? Reply
  • pr1mal0ne - Monday, December 9, 2013 - link

    I disagree with you testing all phones at maximum volume level
    1) the max volume differs, some companies may reasonably make the choice to let quality suffer while volume improves. at the least volume needs to be reported alongside these quality discussions. Preferably it would be set to a base volume and tested there.
    Reply
  • Tuxedo - Monday, December 9, 2013 - link

    Amazing article. I have always been impressed with audio quality on iPhones and disappointed with GS2, GS3, Atrix, Lumia 900 and now OG-Pro. Really shows how much attention Apple pays to the products they build. Reply
  • edwh - Monday, December 9, 2013 - link

    what about output impedance? Reply
  • fishjunk - Monday, December 9, 2013 - link

    I don't really use the audio jack on my Nexus 5. Are there any tests done on the phone mic and speakers. Reply

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