In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

Q: How can you reduce the jnd?, Context: The just-noticeable difference (jnd) (the threshold at which a change is perceived) depends on the tone's frequency content. Below 500 Hz, the jnd is about 3 Hz for sine waves, and 1 Hz for complex tones; above 1000 Hz, the jnd for sine waves is about 0.6% (about 10 cents). The jnd is typically tested by playing two tones in quick succession with the listener asked if there was a difference in their pitches. The jnd becomes smaller if the two tones are played simultaneously as the listener is then able to discern beat frequencies. The total number of perceptible pitch steps in the range of human hearing is about 1,400; the total number of notes in the equal-tempered scale, from 16 to 16,000 Hz, is 120.

A: two tones are played simultaneously
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Q: What is needed to prove the theory?, Context: In the early 11th century, the Muslim physicist Ibn al-Haytham (Alhacen or Alhazen) discussed space perception and its epistemological implications in his Book of Optics (1021), he also rejected Aristotle's definition of topos (Physics IV) by way of geometric demonstrations and defined place as a mathematical spatial extension. His experimental proof of the intromission model of vision led to changes in the understanding of the visual perception of space, contrary to the previous emission theory of vision supported by Euclid and Ptolemy. In "tying the visual perception of space to prior bodily experience, Alhacen unequivocally rejected the intuitiveness of spatial perception and, therefore, the autonomy of vision. Without tangible notions of distance and size for correlation, sight can tell us next to nothing about such things."

A: vision
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Q: Who helped make the religion more popular?, Context: It gained great momentum in the 18th and 19th centuries with the emergence of Methodism and the Great Awakenings in Britain and North America. The origins of Evangelicalism are usually traced back to the English Methodist movement, Nicolaus Zinzendorf, the Moravian Church, Lutheran pietism, Presbyterianism and Puritanism. Among leaders and major figures of the Evangelical Protestant movement were John Wesley, George Whitefield, Jonathan Edwards, Billy Graham, Harold John Ockenga, John Stott and Martyn Lloyd-Jones.

A:
John Wesley, George Whitefield, Jonathan Edwards, Billy Graham, Harold John Ockenga, John Stott and Martyn Lloyd-Jones
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