Section 73.403 - Digital audio broadcasting service requirements(a) Broadcast radio stations using IBOC must transmit at least one over-the-air digital audio programming stream at no direct charge to listeners. In addition, a hybrid broadcast radio station must simulcast its analog audio programming on one of its digital audio programming streams. The DAB audio programming stream that is provided pursuant to this paragraph (a) must be at least comparable in sound quality with a standard analog broadcast.(b) Emergency information. The emergency information requirements found in § 73.1250 shall apply to all free DAB programming streams.72 FR 45692, Aug. 15, 2007, as amended at 85 FR 78027, Dec. 3, 2020