It doesn't have a "frequency" per se. It consists of filtered pink noise that spans approximately the octave centered around 1kHz. The LFE test tone is low passed pink noise with the cutoff around 120Hz, I believe.

Pink noise is a variant on white noise, which like white light, covers all frequencies within it's bandwidth limits. Pink noise contains equal energy per octave while white noise contains equal energy for all frquencies. Only pink noise is used in audio calibration.