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If anyone can supply me with a link to an official file considered to represent "FM quality", or an official definition, I'd be obliged. Over the years I've seen many references to "FM quality" but no actual definition, or sample file. My own experience is that using an older horizontally polarised external TV antenna connected to a medium quality AVR in a high signal strength metroplolitan reception area provides me with reception with a subjectively very good audio quality. For my ears, for a range of program material, it is markedly better than 48kbps DAB+, somewhat better than 64kbps DAB+. For my ears for classical music, it is noticeably better than 80kbps DAB+. I've found a modern car FM radio can also perform well, though with greater noise and subject to occasional glitches from multipath reception as the car moves along the road. The poor audio quality of real life DAB+ and real life DRM relative to FM radio in a high signal strength reception zone has been mentioned a number of times on this forum over the years. I do not however recall the following research paper having been mentioned or discussed. I happened across it today and thought some forum members beyond myself might find it to be of interest, despite it having been published back in 2013! _____________ Research published in 2013 concluded that a very high bitrate was required to achieve FM quality. This was certainly much more than the 48 or 64kbps commonly used in Australia for DAB+, or the even lower audio bitrates commonly used internationally for DRM30 broadcasting. Access to the full paper requires payment of a fee or possible free access at the discretion of the authors. For the purpose of this thread I will merely rely on: 1. The freely available abstract of the paper. 2. Comments from two sources, being observations by people who have read the paper and prepared relatively formal remarks. Off we go then! 1. The abstract, accessible at http://www.aes.org/e-lib/browse.cfm?elib=16969:- AES E-LIBRARY Perceived Audio Quality of Realistic FM and DAB+ Radio Broadcasting Systems The perceived audio quality of a digital broadcasting system (such as DAB+) is dependent on the type of coding and bit rates selected. Because of bandwidth constraints, the required number of channels, and conflicting auxiliary services, audio quality is sometimes degraded. In designing a broadcast system, it is necessary to have well-defined criteria for minimally acceptable quality. Two studies explored quality criteria and how quality degrades for various bit rates. For DAB+ the subchannel rate should not be less than the currently available maximum of 192 kbits/s for a stereo signal, which would be comparable to the quality of a modern FM system. Rates below 160 kbit/s can significantly degrade certain types of program material. To be truly perceptually transparent, bits rates of close to 300 kbits/s may be needed when using the current generation of coders. Authors: Berg, Jan; Bustad, Christofer; Jonsson, Lars; Mossberg, Lars; Nyberg, Dan Affiliations: Luleå University of Technology, Piteå, Sweden; Swedish Radio, Stockholm, Sweden; Swedish National Laboratory of Forensic Science - SKL, Linköping, Sweden (See document for exact affiliation information.) 2. Comments at http://www.radiojackie.com/im/Digital%20radio%20AES%20research.doc DIGITAL RADIO – AES RESEARCH An important new study has been published in the Journal of the Audio Engineering Society: Perceived Audio Quality of Realistic FM and DAB+ Radio Broadcasting Systems. Many different music and speech samples were used in listening tests with the conclusion that a bit rate "close to 300 kbit/s" is required to avoid falling below FM quality. Neither UK-type DAB (from 1985) nor DAB+ (from 2007) are capable of offering this. This research is significant for two reasons. - For the first time, comparisons are made between digital radio and realistic FM radio. - Processed audio was used, rather than unprocessed sounds. Processed audio (e.g. 'Optimod') is universal in radio. Previous work, with unprocessed sounds, had suggested the necessity of 320 kbit/s to pass the perceptual transparency and statistical undetectability point. This was adopted by the BBC in 2010 for HD Sound in iPlayer. These results with processed audio dispel the notion that the sound quality presently possible via digital radio is found inferior by only a tiny minority of audiophiles. This new evidence, specifically examining everyday radio audio, supports the view that DAB has a role as a supplementary platform but could never prove satisfactory as the sole outlet over the airwaves. Trevor Brook - 11 November 2013 Surrey Electronics - radiofax.org - Editor: radiojackie.com 3. Comments at http://www.engineeringradio.us/blog/2013/11/what-bitrate-is-needed-to-sound-like-analog-fm/ What bitrate is needed to sound like analog FM? By Paul Thurst, on November 25th, 2013 7 comments As it turns out, 300 kbp/s or greater. At least in critical listening environments according to the paper titled Perceived Audio Quality of Realistic FM and DAB+ Radio Broadcasting Systems (.pdf) published by the Journal of the Audio Engineering Society. This work was done by group in Sweden and made various observations with different program material and listening subjects. Each person was given a sample of analog FM audio to listen to, then they listened to various audio selections which were using bit reduction algorithms (AKA CODEC or Compression) and graded each one. The methodology is very thorough and there is little left for subjective interpretation. In less critical listening environments, bit rates of 160-192 kbp/s will work. ... [Note: The article immediately above goes on to provide a detailed table.] I personally am not at all surprised at the reported findings!