SE project would have been impossible without support from people who care

Since 2001 more than 10 000 people have already participated anonymously in distributed blind listening tests on the website. Sound quality ratings of 100+ codecs were computed thanks to them. You can still take part.

Development of measurement procedure according to the new music-based audio metric required dozens of different portable audio players which were granted for testing by volunteers. Their names are on df-slides of tested devices.

Other valuable contributions are mentioned below in chronological order.

2020 Feb. SE project run out of all money. The following people responded to my cry for help on Twitter and Facebook: •Mikhail Paulyshka,Feb10,R5000• •Anonymous,Feb11,R4000• •Anonymous,Feb11,0.0035644BTC• •Alexandr Lavrishev,Feb14,R3000• •Nadezhda Kaznacheeva,Feb14,$100• •Sergey Tsyptsyn,Feb14,R5000• •Elena&Andrey Merzlyakovy,Feb15,R4000• •Deniz Yüksel,Feb17,5EUR• •Anonymous,Feb23,R10000• •Igor Konyukhov & Elena Syrkasheva,Feb25,R4000•

2019 Aug. More than 100 hours of recordings from high-end portable audio players were made by csglinux from HeadFi forum. His outstanding contribution helped to understand better some aspects of df-measurement procedure and to make it mature. Thank you! The cooperation is in progress ...,

2019 Jun. Thank you, ValdikSS and Pali Rohár for cooperation; cool article about Bluetooth SBC XQ came out,

2018 Nov. A nice try to monetize SE project by means of crypto-mining; fails miserably a few months later. There were only a few participants who responded to this innovative way of support and contributed a few hours of mining. They all were anonymous. But there was another volunteer from France, also anonymous, who contributed almost a week of his computing power. Thank you, Anonymous Supporter, we noticed your efforts,

2017 Jul. The first donations for special purpose - purchasing and testing of Bluetooth receiver TS-BTAD01 - made by Pierre and Alexey,

2010 Jul. A visitor of SE site by the name Uhl, who accidentally turned out a human factor engineer, pointed out some shortcomings of our rating bar graphs and suggested a few variants which eliminate those drawbacks. We redesigned the graphs according to his recommendations and since then they perfectly work for us,

2010 May. For the research of ATRAC SP (Type-R) codec three guys - Lee Keywood (, Numinos ( forum) and Mike Rofone (Audio T-board forum) performed recordings of SE test vectors on their equipment. That was the first and very successful case of cooperation with audio enthusiasts outside SE project,

2005 Feb. Elena Merzlyakova, Andrey Merzlyakov, Dmitry Timofeev and Vasily Vasilenko participated in the first listening tests, which confirmed relationship of objectively measured Df parameter with perceived sound quality. The results were included in the AES paper - S.Smirnoff, "DIFFERENCE LEVEL: An objective audio parameter" - presented at the 118-th AES Convention in Barcelona,

2004 Apr. Bernhard Feiten (T-Systems, Deutsche Telekom) kindly found and sent (by fax!) his old research paper "Measuring the Coding Margin of Perceptual Codecs with The Difference Signal" when we were in urgent need for that article.

2000 Jan. Thanks to valuable comments and advices of Jacco Dekkers (Philips Research Laboratories) concerning the nature and essence of the Difference level (Df) parameter, the expression for Df got its final form.


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