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What is SoundExpert

Audio metric that makes a differenceSoundExpert (SE) is an independent non-commercial audio research project, which provides audio quality ratings of sound equipment and technologies such as mp3, aac, wma ... encoders and portable players (to be extended). It is the home for innovative music-based audio metric which works both for objective audio measurements and for listening tests. SE is in beta state because the new audio metric and corresponding listening test design are not widely adopted by audio engineers. So, please, use our ratings with caution.

The new listener-centric audio metric allows to perform objective audio measurements using real-life music material and various technical signals, not only sine waves. Such measurements:
• correlate well to human perception of sound quality
• are valid for digital audio
• do not contradict traditional audio metric but extend it
• are understandable to people without technical background
• can be performed at home using any recording device

The first practical application of the new measurement method can be found on the Portable players page.

The new listening test design helps to hear sound artifacts which are normally beyond threshold of human perception. The core of the new design is sound artifacts amplification technology (SARTAMP), which is backed by the new audio metric. Such amplification is particularly important for testing high-bitrate encoders and high quality audio equipment. This technology is used in SE listening tests since 2005. The tests are blind - participants don't know the particular device they assess. Resulting quality scores are completely unbiased and free from marketing and advertising noise.

Live Listening Tests @SoundExpertThe ratings of encoders are computed in real time while participants of the listening tests send their grades to the rating system. The more participants - the more devices and technologies can be tested. The testing procedure is simple and short enough that anyone, including you, can participate. Just download a test file (<3Mb), listen it (<15s) and send back your grade. Details are in the test file. The more accurate grades - the more reliable ratings.

Detailed but still easy to understand overview of SE distributed listening tests is in the paper Live Listening Tests @SoundExpert.

* * *

The main idea behind SoundExpert project is consumer control over sound quality of various audio equipment and technologies on the market. Production side deserves clearly defined feedback from consumers.

 

 

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Audio quality of OnePlus 6

Audio quality of OnePlus 6

Recording of SE test sequences, played back by OnePlus 6 smartphone

Figure 1. Recording of SE test sequences, played back by OnePlus 6 smartphone. Standard SE test sequence includes 10 test signals and two hours of music material.

 

Thanks to Kostya, who has shared his OnePlus 6 smartphone for testing, we have its objective audio measurements, preformed in accordance with SE df-metric:

Df-slide showing location of various test signals (including 2 hours of music) on Df scale according to their levels of degradation

Figure 2. Df-slide showing location of various test signals (including 2 hours of music) on Df scale according to their levels of degradation. Artifact signature of OnePlus 6 is similar to the one of Apple portable devices. Df-slides of various players can be compared to each other on the Portable players page.

 

Conclusion:

Audio quality of OnePlus 6 is in line with top smartphones, including Apple iPhones. They all sound similar, at least with 32 Ohm headphones.


 

Appendix

 

1. Diffrograms of 35 tracks of the test set “Variety”, played back through OnePlus 6 smartphone. They show level of waveform degradation of the musical signal divided into 400ms chunks (one pixel each). Median Df values of the tracks are indicated. Click a track to open in full size for quick comparison with similar tracks from another device. More about diffrograms → Diffrogram: visualization of signal differences in audio research.

All-off
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
OnePlus6 - Variety - 1 OnePlus6 - Variety - 2 OnePlus6 - Variety - 3 OnePlus6 - Variety - 4 OnePlus6 - Variety - 5 OnePlus6 - Variety - 6 OnePlus6 - Variety - 7 OnePlus6 - Variety - 8 OnePlus6 - Variety - 9 OnePlus6 - Variety - 10 OnePlus6 - Variety - 11 OnePlus6 - Variety - 12 OnePlus6 - Variety - 13 OnePlus6 - Variety - 14 OnePlus6 - Variety - 15 OnePlus6 - Variety - 16 OnePlus6 - Variety - 17 OnePlus6 - Variety - 18 OnePlus6 - Variety - 19 OnePlus6 - Variety - 20 OnePlus6 - Variety - 21 OnePlus6 - Variety - 22 OnePlus6 - Variety - 23 OnePlus6 - Variety - 24 OnePlus6 - Variety - 25 OnePlus6 - Variety - 26 OnePlus6 - Variety - 27 OnePlus6 - Variety - 28 OnePlus6 - Variety - 29 OnePlus6 - Variety - 30 OnePlus6 - Variety - 31 OnePlus6 - Variety - 32 OnePlus6 - Variety - 33 OnePlus6 - Variety - 34 OnePlus6 - Variety - 35
-30.1 -25.1 -25.2 -32.9 -26.3 -26.7 -31.7 -24.6 -23.8 -23.5 -27.6 -22.9 -23.0 -27.6 -35.4 -26.0 -29.2 -25.2 -32.9 -37.8 -31.4 -23.4 -25.0 -21.3 -27.2 -26.8 -23.7 -20.6 -26.6 -26.0 -25.7 -20.8 -34.1 -25.5 -28.2

 

 

2. Dendrogram of similarity of artifact signatures for the portable players.

Dendrogram showing similarity of artifact signatures of tested players

Figure 7. Dendrogram showing similarity of artifact signatures of tested players. The shorter the link between two players, the more similar their artifact signatures.

 

 

Table 1. Underlying matrix of Spearman distances between artifact signatures for the dendrogramm. The Spearman distance = 0.1 is critical for relation of Df measurements to subjective scores. For the players that have similar artifact signatures (distance < 0.1) their perceived sound quality correlates well to df-measurements performed with substantial amount of real-life music material (histogram medians).
     (1)    (2)    (3)    (4)    (5)    (6)    (7)    (8)
 (1) Apple iPad mini 2
(2) HTC Desire C
(3) HTC Desire C (ba)
(4) Shanling M2s
(5) Shanling M2s (HighGain)
(6) Shanling M2s (gradual)
(7) Apple A1749 adapter
(8) OnePlus 6
        0.0619 0.0972 0.0445 0.0446 0.0334 0.0374 0.0111
0.0619        0.0655 0.0149 0.0147 0.0174 0.1494 0.1029
0.0972 0.0655        0.0651 0.0651 0.0660 0.1710 0.1306
0.0445 0.0149 0.0651        0.0002 0.0024 0.1378 0.0887
0.0446 0.0147 0.0651 0.0002        0.0025 0.1379 0.0888
0.0334 0.0174 0.0660 0.0024 0.0025        0.1229 0.0752
0.0374 0.1494 0.1710 0.1378 0.1379 0.1229        0.0095
0.0111 0.1029 0.1306 0.0887 0.0888 0.0752 0.0095        

 

 

 

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Audio-Transparency Initiative
Audio-Transparency Initiative