In this thesis, I investigate how using AAC audio is reflected on the listening experiences of Finnish Broadcasting Company's (YLE) public radio channels. This matter is current, owing to the aging analogue system YLE uses at the moment. The analogue system is called LOS; the abbreviation comes from the Finnish words for "Wireless Program Contribution". LOS uses partly the same frequencies as the North Atlantic Treaty Organisation (NATO) uses for military co-operation, thus making this frequency desired. At the same time television is using High Definition and Surround sound systems that demand more bandwidth, whereas the radio contribution goes to lower bitrates by using AAC or other algorithms that compress audio for the optimal use of bandwidth. This is the principle reason why there are doubts whether the trend leads into a right direction. In this study YLE's technical producers revise the sound quality after compression and direct their observations to the questions posed in the early stages of this thesis. The results indicate that AAC 64kbit/s 48 KHz mono audio is not sufficient for contribution, when the program is conversational (i.e. speech). However, it is also agreed that when the news constitute the main focus, this audio is adequate for the contribution. When music is the target of contribution, usage of AAC 256 kbit/s 48 KHz stereo sound is widely acknowledged.

YLE has started a project, where the goal is to implement these results to the next generation outside broadcast system for radio.