Essen Associative Code (EsAC) was developed for one-part music, especially
for European folksong databases. The code itself was inspired by the
Chinese notation JIANPU and consists of cyphers (meaning pitches related
to the declared tonic of the mode) and underlines and dots (standing for
rhythmic durations). In addition to the code, several programs have been
written for PC to analyse, listen, transpose and represent melodies.
Conversions are possible into TEX, PCX, MIDI and other formats. The project started in Germany; since 1994 the main EsAC-encoding centre is in Poland where a few thousand tunes have been encoded. Recently the number of items has reached 20.000 songs and instrumental melodies, mostly from Germany, Poland and China, with minor collections from other (mostly European) countries.
The Polish data at esac-data.org has, until 2011, been limited to holdings in the Oskar Kolberg collection (of which c. 900 of the 12,000 songs he gathered have been encoded). Several thousand additional items from northern (Kaszuby) and northeastern (Warmia) Poland were made available online by Ewa Dahlig-Turek in February 2011.
Ewa Dahlig-Turek, who played a pivotal role in preserving and distributing musical data encoded in the EsAC in the years immediately following the death of Helmut Schaffrath (1994), is now Research Director in the Institute of Arts in Warsaw and professor of ethnomusicology in the University of Poznan. She also holds a number of appointments on advisory and governing bodies in Poland, which she represents in the European Science Foundation at Strasbourg.