instruction:
In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
question:
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.
answer:
two tones are played simultaneously


question:
Which came first, the bridge across the Tyne or the first phase of Britain's first urban light rail system?, Context: The city is served by the Tyne and Wear Metro, a system of suburban and underground railways covering much of Tyne and Wear. It was opened in five phases between 1980 and 1984, and was Britain's first urban light rail transit system; two extensions were opened in 1991 and 2002. It was developed from a combination of existing and newly built tracks and stations, with deep-level tunnels constructed through Newcastle city centre. A bridge was built across the Tyne, between Newcastle and Gateshead, and opened by Queen Elizabeth II in 1981. The network is operated by DB Regio on behalf of Nexus and carries over 37 million passengers a year, extending as far as Newcastle Airport, Tynemouth, South Shields and South Hylton in Sunderland. In 2004, the company Marconi designed and constructed the mobile radio system to the underground Metro system. The Metro system was the first in the UK to have mobile phone antennae installed in the tunnels.
answer:
first urban light rail transit system


question:
Which of the following is a type of machine: generators, fire, or fishing?, Context: On 13 February 2008, fire destroyed the fishing factory and the four generators that supplied power to the island. On 14 March 2008, new generators were installed and uninterrupted power was restored. This fire was devastating to the island because fishing is a mainstay of the economy. While a new factory was being planned and built, M/V Kelso came to the island and acted as a factory ship, with island fishermen based on board for stints normally of one week. The new facility was ready in July 2009, for the start of the 2009–10 fishing season.
answer:

generators