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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  • UsernameAlreadyExists - Friday, December 13, 2013 - link

    That would be great. I believe most display tests are run with the same light output to have more reasonable comparisons... I would like to see the same principle here. As a curiosity (or a warning) it would be good to know that above certain levels the sound will deteriorate. Reply
  • bob11d50 - Sunday, December 8, 2013 - link

    I would love to see the distortion of the apple on a standard headphone (16 ohms). They have notoriously bad sound quality all they way back to the first ipod. Apple is a profit company not a quality company.

    I would also like to see a real comparison of battery life on apple products. Like battery life VS screen size in SQ inches. The screen is so small who cares if it can brows the web for 10 hours if you cant see it.

    Also frame rate VS pixel count. Once again I can refresh a 1 pixel screen at 1Mhz but it does not do me any good nor does a 1M Pixel screen at 1 Hz but the spec is the same 1M pixels a second.

    Robert
    Reply
  • NeoteriX - Monday, December 9, 2013 - link

    I am not an Apple evangelist having only owned Android (and WM and Palm) smartphone devices. So with that said, this is a truly ignorant statement. Apple has led the way on several different design and hardware fronts, including display quality and size, camera quality, GPU power, etc., and it's not clear that without their leadership there would be the kind of robust hardware competition there is in the PC and Android space. Reply
  • deasys - Monday, December 9, 2013 - link

    "They have notoriously bad sound quality all they way back to the first iPod"

    Sure, Bob, whatever you say. Of course, there are authoritative sources that disagree with you. For example: http://www.stereophile.com/content/apple-ipod-port... which summarizes by stating, "Excellent, cost-effective audio engineering from an unexpected source."

    I think I'll take Stereophile's word over yours, Bob…
    Reply
  • akdj - Monday, December 9, 2013 - link

    deasys hit the nail on the head Bob---Not sure which iPod/iOS device YOU'VE hear/listened to/had experience with....but as an absolute audio nerd, I can assure you decent audio files sound excellent....my favorite cans right now are the B&W P5s currently, but I've also got 2 pairs of Grados, Sony MDR 7520s, and Sennheiser HD800s for our studio mixing (with B&W Nautilus 802 speakers and Focal SM9 studio monitors). You couldn't be more dead wrong about Apple's sound quality. Perhaps you need to find a new way to 'rip' your music or quit listening to low bitrate MP3s to judge sound quality?
    As far as screen/battery life----WTF does that have to do with this incredibly extensive, exhaustive sound quality review and comparison/contrast between three Android phones and an iPhone?
    Bone to pick, eh?
    LoL----Doesn't matter does it....regardless of the article, review, discussion----always SOMETHING to do with Apple isn't it?
    Reply
  • winchuff - Wednesday, December 18, 2013 - link

    The devil is always in the detail... Unfortunately deasy, the detail you failed to pick up on is that the 'stereophile' tests were performed into the mackintosh powerbook 'line in' impedance and so did not uncover the limitations of the analogue output stage when listening via headphones. Reply
  • winchuff - Wednesday, December 18, 2013 - link

    You're dead right Bob (whatever the other numpties say). The problem with the ipods (except for the first gen iPod nano, which was superb) is down to an underpowered analogue output stage. There is no problem when driving a high impedance 'line out', but it results in clipping and poor bass response when driving (low impedance) headphones. For those of us listening via headphones, the most crucial objective test is performed when driving into a low impedance. If anandtech do the low impedance tests, you will be vindicated for identifying the shortcomings of the apple devices. And the numpties who know no better will eat humble pie. Reply
  • FYoung - Sunday, December 8, 2013 - link

    I commend you for taking this initiative. I agree that audio testing by sites like Anandtech could eventually lead to phones with better sound quality, which is something that has been neglected so far.

    However, I wish you tested the audio quality of phone calls as well. Cell phones are phones, after all. It doesn't look to me that these tests measure the ability of a phone to selectively capture the spoken voice in a loud environment (without omitting the first syllable of a sentence) and reproduce the voice reasonably accurately and reasonably loudly through its speaker, which is what a cell phone must do to function as a phone in real life.

    If no objective and reproducible test currently exists to do this, why not invent one?

    As for me, I have an S3, and I find the speaker volume barely sufficient to hear the caller's voice. I consider this a significant and entirely unnecessary weakness of the S3. A phone's ability to carry a conversation is far more important than its competence as a camera or music player.
    Reply
  • Impulses - Monday, December 9, 2013 - link

    Those might be your priorities, not necessarily everyone else's though. I can tell you I'd be much more concerned how a phone would fare with music than with calls... I use maybe 200-300 voice minutes a month but I probably spend at least twice as long listening to music/podcasts on my phone (if not thrice as long).

    In the same vein, I couldn't care less about the camera as long as it's usable enough for basic stuff like snapping a pic of something as a reminder while I'm at a store... I still use my pocket camera or my micro four thirds camera for any picture of any moment I'd truly like to remember.

    However I KNOW that's not a majority view and for many many people a smartphone is now their primary camera, so I can appreciate the efforts Brian puts towards evaluating those. I'd imagine that anyone who speaks a ton on their smartphone probably uses a Bluetooth device and I'd bet that's ultimately a bigger factor in call quality (along with the network).

    Not saying it wouldn't be interesting to test mind you, just adding some perspective.
    Reply
  • DarkXale - Monday, December 9, 2013 - link

    Aside from lacking more precise test methodology, and having way too many variables compared to reality to make the tests reliable in reality - such evaluations are already fairly regularly performed during reviews of the device.

    Do keep in mind most carriers will not support frequencies outside the 300-3400mHz range; inadequate for a decent voice conversation.

    If you are concerned about voice quality, your first priority should be to get the carriers to support wideband audio. Without it, the phone manufacturers themselves can't do that much.

    Apple only introduced it with the iPhone 5, but others like Nokia have supported it in their phones far longer, even prior to the release of Windows Phone (7), including support in virtually every device they've released. (Whether its a low end Asha, Lumia 500/520, or a high end 900/920).
    Even the popular Galaxy 2, 3, and 4 support it - so there is no shortage of devices with the capability.
    Reply

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