For example, of the two words lion and lioness, lion is unmarked for gender (it can denote either a male or female) whereas lioness is marked, since it denotes only females. b. Explicitly characterized by or having a particular linguistic feature.
20 Hertz to 20,000 Hertz is the frequency response range that a human can hear. So in answer to your question 20 Hertz would be the lowest pitch a human can hear.
Hmm, what? Yes, humans, under special circumstances, can hear radio-frequency pulses in the range of 2.4MHz to 10GHz (corresponding to radio frequencies and microwave) as buzzes, clocks, hiss or knocking at apparent auditory frequencies of 5kHz and higher (very high-pitched).