Hydrogenaudio Listening Tests

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One of the most visible ways that HydrogenAudio members have shown their enthusiasm for audio quality and their respect for scientific principles over the years is by organizing and participating in public blind listening tests of lossy codecs and presenting statistical analyses of the results. These results show the advantages and disadvantages of different formats and encoders and help identify which are "state of the art."

Private listening tests also provide useful data, but the public HydrogenAudio tests are a rarity in having enough participants to both average out variations among individual listeners and still have statistically significant results.

Note that a listening test cannot really compare formats or encoder "brands." Instead, it compares particular versions of particular encoders at particular bitrates. Results will differ with different encoders, newer versions of the same encoders, or different bitrates. Use caution when extrapolating, and use the most recent results when extrapolating to the newest encoder versions.

Note: There would be no point in listening tests of lossless encoders; the decoded results are bit-identical to the original uncompressed recordings. Lossless encoder comparisons instead consider technical aspects such as compression ratio and encode/decode speed.

All tests are sorted by date, newest first. All dates are in ISO8601 format.

Tests and Results[edit]

Result Symbol Key
> Better than
~ About the same as
~> About the same, but slightly better than

Multiformat Tests[edit]

Date Title
Samples
Performed by Codecs Result Links
2014-07 96-kbps
General
Kamedo2 Apple AAC (iTunes 11.2.2), Opus (1.1),
Vorbis (aoTuV Beta6.03), MP3 (LAME 3.99.5)
Opus > Apple >
MP3(V5) ~ Vorbis
HA Thread
Complete Result
2011-04-10 64-kbps
General
IgorC Vorbis aoTuV, Quicktime HE-AAC, Opus Opus > Apple >
Nero ~ Vorbis
HA Thread
Complete Result
2007-08-16 64-kbps
General
Sebastian Mares Vorbis aoTuV, Nero AAC,
WMA Pro
Nero > WMA Pro ~ Vorbis HA Thread
Complete Result
2006-11-22 48-kbps
General
Sebastian Mares Vorbis aoTuV, Nero AAC,
WMA Pro, WMA Standard
Nero > WMA Pro ~ Vorbis >
WMA Standard
HA Thread
Complete Result
2006-01-13 128-kbps
General
Sebastian Mares QuickTime AAC, Nero AAC, LAME MP3,
Vorbis aoTuV, WMA Pro
5-way tie HA Thread
Complete Result

AAC Tests[edit]

Date Title
Samples
Performed by Codecs Result Links
2011-08-20 96-kbps
General
IgorC CT, FhG AAC via Winamp (not FDK), Nero, QuickTime TVBR & CVBR Quicktime CVBR ~> TVBR ~>
Fraunhofer > CT > Nero
HA Thread
Complete result
2006-02-20 48-kbps HE-AAC
General
Gabriel 3gpp (v1), CT (v1 & v2), Nero (v1 & v2) All tie for most sample types;
otherwise any v1 > any v2
HA Thread
Complete Result
2006-02-05 48-kbps HE-AAC
Classical
Ivan Dimkovic Nero HE-AAC v1 & v2 HA Thread

MP3 Tests[edit]

Date Title
Samples
Performed by Codecs Result Links
2008-10-17 130-kbps
General
Sebastian Mares LAME 3.97, LAME 3.98.2, iTunes, FhG MP3, Helix HA Thread
Complete Result

External Tests[edit]

Other people have held listening tests in venues outside of Hydrogenaudio (although the organizers of the tests tend to be HA members :). The results of these tests are found below: