CREATE TABLE table_73540 ("Horizontal order" FLOAT, "Height order" FLOAT, "Soundfield type" TEXT, "Number of channels" FLOAT, "Channels" TEXT)

If the height order is 1 and the soundfield type is mixed-order, what are all the channels?
SELECT "Channels" FROM table_73540 WHERE "Soundfield type" = 'mixed-order' AND "Height order" = '1'
SELECT "Channels" FROM "table_73540" WHERE "Height order" = '1' AND "Soundfield type" = 'mixed-order'