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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  • sonci - Friday, December 13, 2013 - link

    Thanks Anandtech,
    Nice for doing these reviews, one of my top reasons for choosing a smartphone is audio quality, and im not talking about the voice of my wife, but the music reproduced through earbuds.
    Please keep going testing at full volume not only for those who use them with an external integrated, but because that's the right way, if manufactures bost the volume and allow clipping than thats a flaw, also if a phone measure good at full volume than its super good at low volumes, you also can measure them at a specific sound pressure levels, though the difference should be small, but anyway these are not reviews for the casual listener,
    and Yes unfourtunately iphones sound very good.
    I also would be interested in measuring some old and new mp3 players, though in that case its different to be objective, because for a n audio player SQ is a major selling point, but I dont see Lumia selling more than Galaxie because of better SQ.
    If you cant find any old mp3 player, we are crazy enough to send them to you, hoping to have them back once tested.
    Thanks
    Reply
  • Mokona512 - Saturday, December 14, 2013 - link

    Can you do a comparison of smartphones and dedicated mp3 players?

    for example my sandisk sansa running rockbox firmare gives much better audio quality than my smartphone, especially when driving my akg k240.
    Reply
  • cb474 - Saturday, December 14, 2013 - link

    I appreciate the sophistication and thoroughness of this review. But I have to say that I have never had a smartphone where I've thought, boy this audio quality is unacceptable. Especially with earbuds or plugged into an external system. Unless you're an audiophile, they all seem pretty good to me.

    Speakers on smartphones are obviously another story.

    But to me the real issue is call quality, including earpiece volume, sound quality of the mic (for one's caller), and especially noise cancellation. Anandtech, thankfully, covers noise cancellation in its reviews with a meaningful babble track test. But I wish there were still much more focus on call quality. There are real differences when it comes to call quality, even amongst flagship phones, and this is an area in which, on a daily basis, I experience frustration. It's amazing how much the "phone" functionality of something that is after all phone is ignored.
    Reply
  • kevmitch - Sunday, December 15, 2013 - link

    I agree. Excellent article. I hope to see more like it and on the subject.

    I wouldn't mind the "sensational" scales so much if they were at least used consistently. It was difficult to compare for example the THD FFT responses by tabbing between them in browser windows because the scales aren't the same.

    While the max volume should really be set correctly, it would nevertheless be interesting to see the THD FFT for what SHOULD have been the max volume (i.e., a step or two below the G2). I have to say I'm a lot less excited about getting a Nexus 5 now - the Galaxy 4 looks much more appealing in spite of the significant price increase. These results even had me consider getting an iPhone for about half a second.
    Reply
  • vang024 - Monday, December 16, 2013 - link

    Sorry, but shouldn't you be using lower impedance headphones? The grado is rated at 32 ohms and the K 701 is rated at 64 ohms. The grado might be ok for portable electronics use but the K 701 is more difficult to drive than the 64ohms it is rated at. Not only that, but they are both open headphones which leaks tons of sound and not prefer for anybody using a portable electronic as their music source.

    I think you have to inform the reader the difference between a closed and open headphones(assume they don't know the difference). I see people purchasing a HD600/650 or an AKG Q702 and complains about the sound leakage when these headphones are design to do so. Most of the time people will purchase headphones like a B&W P5/P7, KEF M500, Bose, or Beats for portable use because they are closed design with low impedance. I would say those are targeted for smartphone users.

    I am not saying you shouldn't test smartphone devices with higher impedance headphones, but The Grado and AKGs are not designed for the average joe who don't know much about headphone technologies.
    Reply
  • bogdan.anghel - Thursday, December 19, 2013 - link

    i listen to a lot of music on headphones, i own a S3, and i want to upgrade to S4 and everywhere i see a review the audio quality and power is very bad. should i go with the HTC One? audio and design is very important to me. (i love the S4 but in terms of audio and design, it's crappy) do any of you guys test or compare those 2 on the same headphones? Reply
  • manveruppd - Friday, December 20, 2013 - link

    It's great to see you pushing the boundaries of phone reviewing by testing things that noone else bothers to, and with a scientific precision no one else can match, but i do have a couple of suggestions:
    firstly, how about also testing the quality of the built in speakers, rather than just the headphone amp? after all, sound qquality in calls is an important consideration when buying a phone. as for the loudspeaker, while i agree that noone except annoying teenagers would listen to music through their phone's loudspeaker, a lot of people use the speakerphone function on their phones regularly, so it's a legitimate area of testing.
    secondly, i wonder if it's fair to test all phones with a set of ear buds designed for one phone? if i were a manufacturer i would make sure to bundle a set of buds that sound good driven by the headphone amp i built into my phone, and i would expect it not to do as well with a higher impendance pair of headphones,for example. so to test on apple buds is probably not quite fair on other devices. i would simply pick 3 pairs of headphones, one each of high, low, and medium impendance, made by some reputable audio brand rather than by the manufacturrer of one of the tested devices.
    good job though, looking forward to future review
    Reply
  • synaesthetic - Thursday, December 26, 2013 - link

    output impedance please! Reply
  • seshraj - Wednesday, January 1, 2014 - link

    Thanks for another wonderful post.

    One suggestion to include one Xperia smartphone in your list to test. I personally use an discontinued model Arc S for close to 3 years now and have always been pleased with the bravia audio quality and output, sunlight visibility and camera. I am not a techie or a heavy user of a smartphone; but amazed with the audio quality of this device. I am sure the newer models like Xperia Z would have a more upgraded and better sound quality.
    Reply
  • jcazes - Tuesday, January 7, 2014 - link

    Can anyone comment on how these deficiencies translate to A2DP streaming over bluetooth? I have an LG G2 and am looking at finding something with Apt-X / aptX support (or cooking it in via a custom ROM, if possible). If the phone can't output audio properly over any channel then I don't want to waste my time. Reply

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