Audio quality of portable players

As perceived audio quality of portable players depends mostly on performance of their digital and analog hardware circuits, objective audio measurements are important. At SoundExpert such measurements are performed in accordance with the innovative, music-based audio metric, which:

  • correlates well to perceived sound quality
  • is understandable to people without technical background; more ►
  • uses clear and simple measurement method with open source measurement software; more ►
  • measurement procedure is mature enough thanks to two years of beta testing with 30+ players; more ►

These audio measurements are shown in df-slides. One player - one slide. The most meaningful value on df-slide is histogram median, which is assumed to correlate well to perceived sound quality (the research is still in progress). The less the value, the higher playback fidelity. The opening map summerises such medians for all tested players.


<------------ Higher Fidelity

Df Scale


  iPad mini 2


  Desire C






Df-slides below are sorted by histogram median. Top df-slides represent portable players with higher playback fidelity.

Results of Apple iPad mini 2 audio measurements back to map


Results of Shanling M2s audio measurements back to map


Results of htc Desire C audio measurementsback to map

We can perform such revealing audio measurements for any portable player you wish. Suggest a player for testing and share some of your computing power in our cashless crowdfunding campaign, so we can buy it and test. Tested players will be sold for the purpose of buying more accurate recorder which will allow testing of receivers, amplifiers, D/A converters ...





How To Read Df-slides

The new audio metric has only one measurable parameter - the Difference Level (Df, dB) which measures degradation of an input signal waveform in a device under test. Input (reference) signals can be of any kind - sine, white noise, music, voice, etc. Df-slide shows such Df measurements with some basic technical signals and real-life audio material.

A set of resulting Df values is in fact an objective representation of so called sound signature or, to be more correct, artifact signature of a device.





How audio quality is measured

During the measurement procedure a portable player plays various music material and technical signals, while high resolution recorder records signal at the player's headphone jack. Afterwards, special algorithm compares initial and output waveforms and computes Difference Level(s) [Df, dB] for the latter.

Early research shows that in most cases such levels of degradation, computed with substantial amount of sound material, correspond well to perceived sound quality estimations.

The test sequence at the moment consists of 10 technical signals (sine, square, white noise, ...) and 35 full tracks of various genres, 2 hours in total (SE test set of music material "Variety").



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