In article, the quality of the following encoders was analyzed: mp3, AAC, wma and OGG Vorbis. An original graphic method was used to carry out the quantitative research. It consists in comparing the number of pixels (representing data) between the spectrogram of a wav file and the spectrograms of files compressed with different codecs and bit rates. It has been shown that the Ogg Vorbis encoder retains the most data from the uncompressed wav sample in all tested bit rates (128KBit / s, 160KBit / s, 320KBit / s)
