Smartphone Audio Quality Testingby Chris Heinonen on December 8, 2013 5:15 PM EST
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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.
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psuedonymous - Monday, December 9, 2013 - linkAny chance of a test/roundup of bluetooth receivers?
Impulses - Monday, December 9, 2013 - linkI'd love to see that.
deathdemon89 - Monday, December 9, 2013 - linkI do hope you consider providing the audio tests in the main review on the day it's published, as opposed to tacking it on later. I usually read reviews only once, i.e. on the day they are published and don't keep returning to individual reviews looking for updates, so this would be a major data point readers like me would not be able to take advantage of.
DanNeely - Monday, December 9, 2013 - linkI wouldn't hold my breath. Chris H isn't a typical smartphone reviewer. As a result getting these results at initial launch time would require either buying additional sets of test equipment for the reviewers, buying an additional phone for Chris H to do audio testing on, or delaying the article to ship the phone to Chris H after completing the rest of the testing work.
Audio precision won't let you see pricing information without creating an account on their website. That suggests it's painfully expensive and that getting multiple copies of the hardware won't happen. Getting multiple copies of the phone isn't cheap either and is probably not going to happen except perhaps for a few halo devices. With the peanut gallery raging about any reviews that don't make it out on release day, I'm doubtful that anandtech would choose to delay reviews for a few days for a specialized test.
Impulses - Monday, December 9, 2013 - linkEhh, I agree, if it's not realistic to have this testing the day the review is out it's no big deal... If it's a deal breaker for you then you'd wait the same amount of time either way, and if it's not (probably the majority of readers) then there's no point in making the rest wait.
xaml - Saturday, December 14, 2013 - link"Chris H isn't a typical smartphone reviewer. As a result getting these results at initial launch time would require either buying additional sets of test equipment for the reviewers, buying an additional phone for Chris H to do audio testing on, or delaying the article to ship the phone to Chris H after completing the rest of the testing work."
Or buying an additional Chris H...
cheinonen - Monday, December 9, 2013 - linkHaving this on the day-of is going to be a challenge for a number of reasons.
- Brian is in Arizona, and I'm in Oregon. If there is only a single review sample, I have to get it from him.
- As mentioned, the Audio Precision is ridiculously expensive. I think the APx 582 used starts at $19,000 before adding the HDMI, Bluetooth, and Digital modules I use (I need it for receivers as well). Audio Precision is just a few minutes from my house and they've been nice enough to let me come in, test everything there, and endlessly bother their QA people to get this right. However, as I have to come in I have to schedule that, and it takes time.
- That also makes it far easier to do a batch of these at a time than one at a time. If I had at APx at home it would be easier but right now that's not possible.
So we will try to get all the data, as fast as possible, into the system, but day-of is going to be a logistical challenge. I'd rather have it be accurate than be fast.
cheinonen - Thursday, December 12, 2013 - linkOK, I shouldn't say ridiculously expensive. However, the instrument we use costs enough that it's not feasible for us to have them for myself, Anand, Brian, and everyone else that needs one for testing. The Audio Precision gear ranges from $6K to $50K+ depending on what you need and the price still means we can't outfit everyone with one. So testing will happen as fast as possible, but likely won't run with the reviews when they are initially posted.
Bobs_Your_Uncle - Monday, December 9, 2013 - linkThis audio bench is a tool of truly significant value to anyone hoping to arrive at the best, most fully informed purchasing decision possible. Given the respect & high regard that AT has earned throughout the tech sector, this audio initiative raises the bar for more than smartphone manufacturers alone.
Along these lines, does AT have any plans to initiate a similar audio bench for the various motherboard lines that have recently implemented enhanced audio capabilities?
These are very positive steps toward driving advances in fundamental, yet long neglected platform capabilities. However, as improvements in audio reproduction are realized, there will still remain one critical, & seemingly intractable obstacle to overcome; What's it going to take for the recording industry to give up on compression & adopt a regimen of decent mastering.?
It'd be a shame if the only thing audiophile-grade tech revealed was just how badly most studios butcher great music through compression & lousy mastering.
Impulses - Monday, December 9, 2013 - linkI think that battle's beyond Anandtech'srealm, though the more cognizant the average reader/listener is the better.