Frequency measures a player's ability to reproduce all frequencies between 20Hz and 20kHz equally well. The lower the number, the better; generally speaking, a number of less than 3dB is considered flat. Unlike in the first two tests, the Cowon iAudio U3 did extremely well, nearing 0dB, while the Sony PSP, the Archos Gmini 402 Camcorder, and the iPod Shuffle and Nano came in at less than 3dB.