Radio advertisement
（重定向自Radio advertising）
In the US, commercial radio stations make most of their revenue selling "airtime" to advertisers. Of total media expenditures, radio accounts for 6.9%. Radio advertisements or "spots" are available when a business or service provides valuable consideration, usually cash, in exchange for the station airing their spot or mentioning them on air. The United States Federal Communications Commission (FCC), established under the Communications Act of 1934, regulates commercial broadcasting, and the laws regarding radio advertisements remain relatively unchanged from the original Radio Act of 1927, enacted to deal with increasing problems of signal interference as more and more stations sprung up around the country.