 
 <prompt> Wetin go happun if pesin dey hear two tones at di same time? Based on di previous question, write one context wey contain di answer. E fit be 1 - 20 sentences. Context: <response>: ```Di just-noticeable difference (jnd) (di threshold wey change fit dey noticed) dey depend on di frequency content of di tone. Below 500 Hz, di jnd na about 3 Hz for sine waves, and 1 Hz for complex tones; above 1000 Hz, di jnd for sine waves na about 0.6% (about 10 cents). Dem dey typically test di jnd by playing two tones quick quick and ask di listener if dem get difference for dia pitches. Di jnd go dey smaller if dem play di two tones at di same time as di listener fit sabi beat frequencies. Di total number of perceptible pitch steps for di range of human hearing na about 1,400; di total number of notes for di equal-tempered scale, from 16 to 16,000 Hz, na 120.``` 