If after these one bitcoin to sgd price is higher you will here “up” sound, if lower, “down” sound, and if it stays the same “no change” sound. If you set it to 0. This setting is currency specific setting.
It won’t work if you switch to another currency. The chart below is the price change over time. The yellow line is the price at which actual trades were made. Green and red areas near the yellow line show you maximum and minimum price.