Polyphony and monophony in instruments harpejji and the Chapman stick). Multiphonics can be used with many regular wind instruments to produce two or more notes at once, although this is considered an extended technique. Explicitly polyphonic wind instruments are relatively rare, but do exist. The standard harmonica can easily produce several notes at once. Multichambered ocarinas are manufactured in a number of varieties, including double, triple, and quadruple ocarinas, which use multiple chambers to extend the ocarina's otherwise limited range, but also enable the musician to play more than one note simultaneously. Harmonic ocarinas are specifically designed for polyphony, and in these instruments the range
Owned-and-operated television stations in the United States order to stay under the ownership cap. In addition, networks may choose to sell off O&Os in smaller markets in order to concentrate on their stations in larger markets, or to give themselves leeway to purchase stations in other growing markets. The following are examples of transactions involving owned-and-operated stations in the United States: The DuMont network found itself in financial trouble in 1954, and decided to sell off its Pittsburgh owned-and-operated station, WDTV (channel 2), which was the only commercial VHF station in what was then a top ten television market in the United States. Westinghouse Electric Corporation bought