###### Abstract  
The process of digitizing radio is far from over. It is an important interdisciplinary aspect, involving Big Data and AI (Artificial Intelligence) when it comes to classifying and handling content, and an organizational challenge in the Industry 4.0 concept. There exist several methods for delivering audio signals, including terrestrial broadcasting and internet streaming. Among them, the DAB+ (Digital Audio Broadcasting plus) system is one of the leading standards of terrestrial digital radio transmission. Compared with analog FM (frequency modulation) radio, it is more bandwidth efficient and offers greater possibilities when it comes to delivering content and forming an ensemble and multiplex. Currently, many countries worldwide, particularly European States, are still making adjustments in order to perform an efficient switchover from analog FM to digital DAB+ radio. This paper presents the current situation of the digital radio market as well as the results of a subjective quality evaluation study and questionnaire concerning broadcasting in both digital and analog techniques. It involves radio programs, transmitting both speech and music signals, simulcasted in DAB+ and FM standards. It also presents the development of the national multiplex. The results of this study may help both researchers and scientists as well as policy makers and professionals active in the field of broadcasting and electronic media and not to mention the consumption of multimedia content. audio; broadcasting; coding; compression; DAB+ (Digital Audio Broadcasting plus); digital transformation; signal processing; switchover; radio transmission +
Footnote †: journal: Applied Sciences  
Applied Sciences  
broadcasting industry. Whether we are talking about terrestrial or online radio transmission, they all require efficient and reliable technologies. The most up-to-date technologies include interdisciplinary fields such as deep learning, machine learning, and AI (artificial intelligence) [1; 2; 3; 4; 5]. Nowadays, digitization becomes very important, and with the advent of the Industry 4.0 concept, even terrestrial radio transmission will have to face a digital transformation. In this case, we refer to it as a switchover that is most often related with the migration from analog FM (frequency modulation) to digital DAB+ (Digital Audio Broadcasting plus) radio. This challenge brings together computer scientists, electrical engineers, sound engineers, and specialists from the field of medical healthcare, psychology, and various arts. Since simulcasting involves a simultaneous transmission of the same audio content, it automatically causes excessive consumption or even a waste of resources being either hardware, energy, or human resources. That is why it is important to study how the quality of radio programs is perceived by end users and whether the time has come for an efficient migration to digital technology. The paper is organized as follows: Section 2 presents the current situation of the digital radio market, including the availability as well as penetration of the DAB+ standard. Section 3 describes the state of the art and advancements in both subjective and objective studies of digital and analog broadcasting carried out by scientists from all around the world. Section 4 shows the multiplex configuration of the analyzed DAB+ ensemble, including adjustments in number of available services, their profile, type of transmitted audio content, and assigned resources, namely bitrate. Section 5 is focused on the results of a subjective quality evaluation of simulcasted analog FM and digital DAB+ broadcasts compared to an earlier study of the same ensemble including its previous configuration. Section 6 deliberates on the results of a questionnaire and is focused on parameters and factors necessary for a successful switchover. Section 7 discusses results before and after modifying the analyzed multiplex ensemble. Section 8 concludes and summarizes the paper, pointing out possible future studies and directions for further research.