Editing Digital Audio Broadcasting (section)

==Sound quality==
{{See also|MPEG-1#Quality|l1=MP2 quality}}
The original objectives of converting to digital transmission were to enable higher audio [[fidelity]], more stations and more resistance to noise, co-channel interference and [[multipath propagation|multipath]] than in analogue FM radio. The improved sound quality is achieved by using CRC and FEC technology, which improves the transmission performance of digital signals.<ref>{{Cite web |last=Belousov |first=Dima |date=4 February 2023 |title=Why DMR Radio? Top 10 Benefits of DMR Technology Crunch Reviews |url=https://www.crunchreviews.com/audio/why-dmr-radio-and-key-benefits-of-dmr-technology/ |access-date=30 June 2023 |website=www.crunchreviews.com |language=en-US |archive-date=30 June 2023 |archive-url=https://web.archive.org/web/20230630110610/https://www.crunchreviews.com/audio/why-dmr-radio-and-key-benefits-of-dmr-technology/ |url-status=live }}</ref> However, many countries in implementing DAB on stereo radio stations use compression to such a degree that it produces lower sound quality than that received from FM broadcasts. This is because of the bit rate levels being too low for the [[MPEG-1 Audio Layer II|MPEG Layer 2]] audio codec to provide high fidelity audio quality.<ref name="robinson">{{cite web |url=http://www.david.robinson.org/commsbill/#1_2_3 |title=OFCOM: Regulation in digital broadcasting: DAB digital radio bitrates and audio quality; Dynamic range compression and loudness<!-- Bot generated title --> |website=david.robinson.org |url-status=dead |archive-url=https://web.archive.org/web/20080708211612/http://www.david.robinson.org/commsbill#1_2_3 |archive-date=8 July 2008}}</ref>

The [[BBC]] Research & Development department states that at least 192&nbsp;kbit/s is necessary for a high fidelity stereo broadcast:

{{blockquote|A value of 256&nbsp;kbit/s has been judged to provide a high quality stereo broadcast signal. However, a small reduction, to 224&nbsp;kbit/s is often adequate, and in some cases it may be possible to accept a further reduction to 192&nbsp;kbit/s, especially if redundancy in the stereo signal is exploited by a process of 'joint stereo' encoding (i.e. some sounds appearing at the centre of the stereo image need not be sent twice). At 192&nbsp;kbit/s, it is relatively easy to hear imperfections in critical audio material.|BBC R&D White Paper WHP 061 June 2003<ref name=":1">{{cite web |url=http://downloads.bbc.co.uk/rd/pubs/whp/whp-pdf-files/WHP061.pdf |title=BBC R&D White Paper WHP 061 June 2003, DAB:An introduction to the EUREKA DAB System and a guide to how it works |publisher=BBC.co.uk |access-date=2007-05-08 |archive-date=2009-03-04 |archive-url=https://web.archive.org/web/20090304001258/http://downloads.bbc.co.uk/rd/pubs/whp/whp-pdf-files/WHP061.pdf |url-status=live }}</ref>}}

When the BBC reduced the bit-rate of transmission of its classical music station [[BBC Radio 3|Radio 3]] from 192&nbsp;kbit/s to 160&nbsp;kbit/s in July 2006, the resulting degradation of audio quality prompted a number of complaints to the corporation.<ref>{{cite web |url=http://www.for3.org/third/BBC_R3_news_archive.html#poorDAB |title=Friends of Radio 3 (FoR3) BBC & R3 News<!-- Bot generated title --> |website=for3.org |url-status=dead |archive-url=https://web.archive.org/web/20081006090237/http://www.for3.org/third/BBC_R3_news_archive.html#poorDAB |archive-date=6 October 2008}}</ref> The BBC later announced that following this testing of new equipment, it would resume the previous practice of transmitting Radio 3 at 192&nbsp;kbit/s whenever there were no other demands on bandwidth. (For comparison, BBC Radio 3 and all other BBC radio stations are streamed online using [[Advanced Audio Coding|AAC]] at 320&nbsp;kbit/s, described as 'HD', on [[iPlayer|BBC Radio iPlayer]] after a period when it was available at two different bit rates.)

Despite the above, a survey in 2007 of DAB listeners (including mobile) has shown most find DAB to have equal or better sound quality than FM.<ref>{{cite web |url=http://www.digitalspy.co.uk/broadcasting/news/a45367/ofcom-reveals-dab-sound-quality-opinions.html |title=Ofcom reveals DAB sound quality opinions |author=James Welsh |work=Digital Spy |date=17 April 2007 |access-date=26 November 2009 |archive-date=9 May 2010 |archive-url=https://web.archive.org/web/20100509172412/http://www.digitalspy.co.uk/broadcasting/news/a45367/ofcom-reveals-dab-sound-quality-opinions.html |url-status=dead }}</ref>

By 2019, some stations had upgraded to DAB+ but rather than improving sound quality, they instead reduced it to 32&nbsp;kbit/s or 64&nbsp;kbit/s, often in mono.<ref>{{cite web |url=https://www.youtube.com/watch?v=27w3quNTP84 |title=Why DAB sounds so BAD - the UK's digital radio shambles |author=Techmoan |website=[[YouTube]] |date=7 January 2022 |access-date=7 January 2022 |archive-date=7 January 2022 |archive-url=https://web.archive.org/web/20220107233728/https://www.youtube.com/watch?v=27w3quNTP84 |url-status=live }}</ref>