Smartphone Audio Quality Testing
by Chris Heinonen on December 8, 2013 5:15 PM EST- Posted in
- Smartphones
- Audio
- Mobile
- Tablets
- Testing
In many of the examples you have seen so far, you notice that the Nexus 5 has a large issue with the left channel at peak volume levels. As Brian mentions in his Nexus 5 review, it is based on a similar platform to the LG G2 but it isn't identical. Because there are similarities I want to test it out and see if it has the same issue that I see on the Nexus 5.
The test that is causing the large issue on the Nexus 5 is a 1 kHz sine wave, at -0dBFS, at maximum volume. This is the loudest sound that any device will be asked to produce. If you're familiar with the trends in music mixing the past two decades you'll know that a peak of -0dBFS is not all that uncommon now. This chart at NPR shows the average and peak levels for the most popular songs over the past thirty years. Two decades ago testing for -0dBFS might not have been important but it is now. So lets look at this image from the Nexus 5 again.
Now for comparison, we will look at the LG G2.
This looks much better. However the LG G2 is still putting out 0.546528% THD+N into the left channel while only outputting 0.003338% into the right channel. So there is still some imbalance going on here. So why is the issue so much less on the G2 than on the Nexus 5?
The key to this is looking at the scale on the graphs here. While the Nexus 5 peaks are up close to 1.3-1.4V, the G2 has peaks that don't even reach 700mV. Looking at the actual numbers the G2 has a Vrms level of 475.3 mVrms while the Nexus 5 checks in at 843.6 mVrms for the left channel and 982 mVrms for the right channel. The G2 is placing far less stress on its headphone amplifier and keeping it from the output levels that cause this excessive clipping in the Nexus 5.
To look in more detail, we have THD+N Ratio charts for the stepped level sweep that we looked at earlier. First, lets look at the Nexus 5.
We see that the first three volume levels, 15-13, have THD+N distortion over 0.3% for the left ear, while they are below 0.01% for the right ear. From level 12 and below the THD+N levels are practically equal. Now to see how this data on the G2 looks.
We see the first volume step has 0.55% THD+N or so for the left ear, but the right ear is down at a similar level to level 14 on the Nexus 5. The next step drops it to 0.03% which is way, way below where it is on the Nexus 5 at that point. By step 13 they are equal.
The conclusion I pull from this is that both the G2 and the Nexus 5 have the exact same flaw right now. However, the G2 has attempted to hide it by reducing the maximum output level of their headphone amplifier. The Nexus 5 can play louder, but only with far more distortion. Given this I would expect there to be an update to the Nexus 5 at some point that lowers the maximum headphone level to something closer to the G2.
However this doesn't mean that the Nexus 5 is certainly worse to use with headphones. The top 3 settings are ones I would avoid due to the left channel issue, but I might avoid the top 1-2 settings on the G2 as well. If we consider 1% THD+N to be the maximum allowable level, that leaves 8 volume steps on the Nexus 5 that are usable. The G2 has 9 steps that are available to you, and 10 if you consider 0.03% THD+N in one ear to be OK (it probably is).
In the end, the G2 won't play as loud as the Nexus 5 will, but you don't want to play that loud anyway. It has more usable volume steps than the Nexus 5, and otherwise very similar numbers. I'll be interested to see if either of them make further changes to their maximum output levels to remove this issue.
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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.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
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.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…
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?
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.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.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.
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.
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.