| DAB sound quality article on You & Yours17th October 2006 BBC Radio has finally broadcast a balanced article on the DAB sound quality issue, with an article on the subject on You and Yours on Radio 4 today. You can download a recording of the interview here: Recording of You & Yours article (2.9 MB) The two interviewees were Jack Schofield, who is the The Guardian's computer correspondent, and Ian Dickens, the chief executive of the DRDB (Digital Radio Development Bureau), which is the marketing arm for DAB in the UK. Jack Schofield's opinions were much the same as what I write on this website:
Ian Dickens, on the other hand, gave highly disingenuous answers, such as: He claimed that FM uses technology that is 100 years old, when in fact FM stereo wasn't developed until the early 1960s. And Ian Dickens is obviously ignoring the fact that FM sounds a lot better than the DAB system despite it being based on much older technology — ironically, the main problem with the DAB system is precisely the fact that it fails even to match the audio quality on the older FM system! He also claimed that DAB sales have taken off in the UK because there's more choice, but sales have not taken off in Germany where stations are transmitted at higher bit rates than in the UK but there's little additional choice. That answer does not stand up to scrutiny whatsoever, because:
As Ian Dickens admitted in the interview, he is a marketing person, so he will know perfectly well how important TV advertising is to sales — advertisers don't pay £50,000 or more for a 30-second TV advert for the good of their health, they pay what seems to you and I like astronomical sums of money to boost the sales of their products. End of story. And totally ignoring the massive amount of TV advertising DAB has had on BBC TV, not to mention a similar number of DRDB-commissioned advertising campaigns on commercial radio, not to mention the fact that pretty much all FM stations that are on DAB seem to have jingles that mention that the station is on DAB these days, it is simply being massively disingenuous, because Ian Dickens will not have been appointed as the chief executive of the DRDB — the organisation responsible for the marketing of DAB in the UK, and the organisation that co-ordinates advertising campaigns for DAB — if he didn't know how important TV and radio advertising is for sales of consumer goods. Then again, as I mentioned above, this article was actually the most balanced that BBC Radio has broadcast on the subject of audio quality on DAB, because previous articles on the subject wouldn't be too dissimilar to what you'd expect from the North Korean government's PR department. Such previous examples — all on Radio 4 — include the time on PM when there was a "debate" about DAB's audio quality, and we had Simon Nelson (another marketing man), who is the BBC Controller in charge of DAB, on one side, and Barry Fox, a technology journalist, on the other side. But Barry Fox is a well-known supporter of DAB, so the debate was obviously about as farcical as a "debate" could possibly be. Other times include when the issue of DAB audio quality was raised on Feedback two years running, and Simon Nelson said that Radio 4 is only reduced to mono when it carries material that was made in mono (that is totally untrue, because Radio 4 is broadcast in mono in the evenings whenever Radio 5 Sports Extra is on-air, and irrespective of whether the material was produced in stereo or mono). And last but not least, there was what I think of being the most inaccurate sentence in the history of human communication, which was uttered by Simon Nelson, BBC Controller of Radio & Music Interactive, which he made right at the end of one of the Radio 4 Feedback interviews (marketing men know that listeners' recognition is highest on what's said at the end of an advert), and with his best Tony Blair style impassioned voice, and following numerous letters that had been read out from listeners who were incredulous at the abysmal audio quality on DAB, he said: “And the message we need to get across is that for the vast majority of people, the sound quality they're getting through their digital radio set is vastly superior to that which they've ever had through their analogue radio.” So much for the BBC being honest... Comments
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DAB sound "quality"
To my ears the DAB sound is plain awful. Harsh and tinged with low level hash that makes listening fatiguing. I have sampled a few DAB radios and they all have this nasty quality.
So if Apple can achieve very aceptable results with 128kb audio why not DAB?
On the plus side its great to have such a great variety of stations and content avaiable.
Just my two pennorth
Alan
MP2 vs AAC
"So if Apple can achieve very aceptable results with 128kb audio why not DAB?"
It's down to the different audio codecs being used. DAB uses MP2, which dates back to the 1980s and it's meant to be used at high bit rates of around 192 kbps+ for stereo streams - the BBC uses MP2 at a bit rate of 256 kbps for the audio on the BBC1, 2, 3 and 4 TV channels, whereas 98% of all stereo stations on DAB in the UK only use 128 kbps MP2. So it's to be expected that DAB sounds as bad as it does because they're completely misusing the codec.
Apple (and iTunes) uses the AAC codec, which was developed in the mid 1990s, and it's optimised to perform very well at 128 kbps. You can see the difference in performance between AAC and MP2 from the figure on this page about bit rate versus audio quality. The curve on the graph for MP2 is labelled "LII", because MP2 is short for MPEG Layer 2, and AAC at 128 kbps performed far better than MP2 did even at 192 kbps when that listening test took place.
The sad thing about DAB is that the BBC had the chance to adopt AAC for DAB before DAB was properly launched in 2002, but they did nothing. It's since become pretty clear that engineers in the BBC R&D department were warning the executives who were making the decisions (none of which understand the technologies they were making decisions on, BTW - that's the new BBC for you) about the consequences of using MP2 at low bit rates, but it seems that the engineers were ignored, and here we are. I've discussed what happened at greater length on the following page about the history of DAB's adoption by the BBC. Basically, the executives didn't have a clue what they were doing.