They cite many reasons for this, the most common among them being background music being too loud.

As a result of these complaints in 2009, Jay Hunt (my predecessor as controller of BBC One) launched an extensive study into why people were experiencing these difficulties.

BBC Vision's Audibility project was a huge undertaking. It involved using our 20,000-strong panel of TV viewers across the age, geographical and social demographic and a good deal of technical experimentation.

This included an engineering analysis of programmes, remixing soundtracks on clips and much more.

We also worked with the Voice Of The Listener And Viewer, Channel 4 and the Royal National Institute For Deaf People to find out once and for all what it is that can make it hard for viewers to hear the dialogue in our programmes properly.

The results were surprising. It turns out that audibility is not just about background music, as many had thought.

In fact issues range from clarity of speech - namely mumbling, muttering and muffled voices - to unfamiliar accents. Background noise such as traffic was also an issue.

However what we discovered was that it was a combination of factors could really create problems - for example a mumbling actor, recorded in a noisy environment with added music.

What struck me is that many of the problems could be resolved long before a single frame is shot if more emphasis was placed on planning for clear sound.

For example, has the director chosen the right location and what are the implications for getting good sound? Has the person looking after sound had training and the right level of experience? Are the presenters briefed to recap if they feel key messages are not clear?

If a contributor may be difficult to understand, can they be in vision as much as possible so viewers can see their lips move?

In testing, when we remixed sound tracks on video clips; with the music taken down a notch the results were fascinating.

Reducing the music by just one point, four decibels, when the programme is finally mixed allowed many more people to understand what was being said without compromising the editorial vision.

This was particularly true for people who had any form of hearing loss.

One invaluable piece of information I've learned along the way is that age-related hearing loss can begin as early as in our 40s. Many of us are completely unaware that our hearing could be deteriorating and think the issue is with TV programmes.

But for me, this is something we need to be aware of - particularly those making programmes for mainstream channels like BBC One.

The result of this research is that we now have a 'best practice' guide for programme makers available on the BBC Academy's College of Production website.

This gives clear guidance on the small things that programme makers can do to make a big difference to the audience's ability to hear and therefore enjoy our programmes to the fullest possible extent.

My thanks to all our partners involved in this project. It has been a fascinating and very useful study.

Danny Cohen is controller of BBC One.

Further guidance has now been published on the BBC's Editorial Guidelines website.

This season we are excited to bring young audiences a unique range of thought-provoking factual programmes, innovative British drama, and unique comedy and entertainment.

2010 has been a very successful year so far. Young audiences are up a further 14%, with the channel reaching over five million 16 to 34s each week. In our broadcast hours, BBC Three is now reaching more young people than E4 and ITV2.

More importantly, viewers are recognising the unique quality and range of the channel's output. In March, our award-winning documentary on the lives of women in post-Taliban Afghanistan - Women, Weddings, War and Me - got the highest audience appreciation score of any factual programme on any channel ever reported. The audience appreciation score is calculated through the TV Pulse survey, which measures our audiences' enjoyment of TV programmes.

Alongside it, series like Blood, Sweat and Luxuries, Being Human, Mongrels, and Russell Howard's Good News, are winning BBC Three great loyalty and affection with young British viewers.

In the coming months, we hope to build on this success with more new programmes, and a rich range to the schedule that young viewers will not find elsewhere on British television.

In current affairs, BBC Three will explore a range of complex subjects that have a particular relevance to young viewers including child soldiers, forced marriages, bullying, and sex trafficking.

Thought-provoking documentary has also become a hallmark of the channel now, and the Adult season this year will provide a context for us to explore themes including caring for a parent with mental health problems, living with blindness, and education.

We are also using the BBC Three blog to hear your stories about growing up and coming of age. If you'd like, you can share your stories and thoughts on the subject, so please join the conversation.

And of course comedy remains central to the channel's remit and reputation. The wonderful talents of Simon Brodkin in break-out hit Lee Nelson's Well Good Show, and the acclaimed adult puppet show Mongrels (see the creator's post on this blog) will be followed this autumn by the return of Johnny Vegas in Ideal and Dan Clark in How Not To Live Your Life.

Alongside these much-loved shows, comes new comedy in the shape of Him And Her. It's a beautifully written piece by Stefan Golaszweski, and stars Russell Tovey and Sarah Solemani.

In drama, we move from the supernatural to the streets of Glasgow for a new lesbian relationship drama, Lip Service. Written by Harriet Braun, it's a seductive and addictive series, and a strong piece of authored work.

And finally in entertainment, Russell Howard returns with more of his Good News, and we're delighted to welcome Simon Bird to BBC Three as the star of a new studio entertainment show, The King Is Dead. It is part panel show, part celebrity interview, and part scripted comedy. It is unique and surprising, with lots of young British talent at its heart.

I hope this gives you a good sense of the creative range of programmes on BBC Three in the coming months. We are now established as a firm favourite with young audiences but we plan to keep working hard to discover exciting new talent, and deliver bold and thought-provoking ideas to young viewers.

Danny Cohen is controller of BBC Three.

The documentary will tell the story of Laura, who has been drinking too much and has received an ASBO related to her alcohol-fuelled behaviour.

This programme is being made with the co-operation of both Laura and her family, and they are not being paid for their involvement.

The family are regularly offered money by newspapers to tell their story but have chosen instead to work with the BBC for no financial gain because they understand the serious, responsible nature of the BBC's documentary approach.

Both Laura and her family are desperate for her to change her behaviour, and the programme will document her attempts, and examine how they cope as a family.

The documentary will follow Laura over time - it is not a snapshot - and observe whether Laura can make good on her ambition to turn her life around. Laura plans to undergo therapy for the first time and the programme will thoughtfully monitor the success of this.

Laura, of course, is not alone. There are a great many young people in Britain who are not drinking at safe levels. BBC Three has a strong track record of making thought-provoking and sensitive documentaries about the big social issues that face young people.

It is absolutely in keeping with the BBC's public service values for these kind of important subjects to be explored on BBC Three, whether it be youth unemployment, teen pregnancy, or alcohol abuse.

Crucially, we have put a working protocol in place to ensure that sensitive documentaries of this nature are made with thoughtfulness and responsibility at their heart.

In this case these measures include no payment to those involved in the filming, carefully controlled filming hours, and a firm commitment to preventing Laura harming herself or anyone else during filming.

One further footnote. The Sun also carried an editorial piece, criticising the programme and BBC Three. I have outlined above the reasons why their criticism of the programme is misplaced. But The Sun also claims that BBC Three is 'a channel nobody watches'.

This is a factually inaccurate statement. BBC Three reaches 15 million people a week, and just under 30 million every month. It is now the most watched digital channel in the hours it broadcasts as a result of hit programmes that include Being Human, Blood Sweat and Luxuries, Russell Howard's Good News, and the channel's recent in-depth general election coverage.

In the coming months and years, we will continue to work hard to provide thought-provoking and compelling programmes for young licence fee-payers.

Danny Cohen is controller of BBC Three

I have no doubt that young people are interested in politics - and the ethical issues that flow from decisions that politicians make. But it's certainly true that younger people are less likely to vote than the general population. In the last General Election, 37% of 18 to 24-year-olds voted and 48% of 25 to 34-year-olds. That's compared to an overall turnout of 61%.

There are lots of reasons for this, but the big question for me at BBC Three is - how can we help make sure young people are fully informed of the choices they have? It may mean that they make an informed decision not to vote - that's democracy - but we'll be working hard in the coming weeks to provide a range of views, and the factual information to help them decide.

BBC Three has a unique role to play in public service television. It's the only youth-focused channel with a regular commitment to news and current affairs. Aside from our General Election coverage, the channel will show documentaries in the coming months on the war in Afghanistan, child trafficking, autism, the use of rape as a weapon of war in the Congo, bullying and the life of Nelson Mandela.

No other youth-focused British channel makes programmes like these on a consistent basis. And with the channel growing 30% in the last two years, we know that young people like the ways in which we approach these subjects for being thought-provoking and stimulating.

So I'm keen for BBC Three to play a significant role in the BBC's General Election coverage - and our plans are already rolling.

Robert Peston has presented a short piece for BBC Three, reminding viewers that they need to register pretty soon in order to be able to vote in the Election. He will follow this up with another TV piece in the run-up to election day that explains the mechanics of voting and how to go about it.

Robert is very committed to reaching young people with news and current affairs and a few weeks before the election he's also going to present a TV and web special on finance for young people. Money, banks and the market are obviously major issues in the coming campaign, and we hope this will provide further useful insights for our audience.

Alongside this, BBC Three has plans for live political debate in the shape of First Time Voters' Question Time on 3 March. Chaired by Dermot O'Leary, this is an opportunity for politicians to respond directly to the concerns and questions of young people - and it's something I'm very excited about.

I'm delighted to have Dermot on board as host for this programme. He's passionate about politics, and I hope he may entice some young people to the programme who may not be naturally drawn to some of the BBC's other political coverage.

Sometimes the decision to use a 'non-specialist' presenter like this can be seen as controversial, but I don't think it really is. The key is to look across the whole of the BBC's output - and make sure that there's a wide range of approaches to suit the different ages, tastes and sensibilities of licence-fee payers.

UPDATE 5 March:

I was really delighted by how First Time Voters' Question Time went on Wednesday. It gave young people a very direct opportunity to talk to politicians, hear their policies, and challenge them on their ideas.

I thought that the questions and comments coming from our audience of First Time Voters was of a very high standard, and showed how passionate young people are about the world they live in and the future of the country.

This was also clear from the hundreds of tweets and texts we received during the programme, picking the panellists up on their ideas, and commenting on the action.

It felt like a great experiment for BBC Three, and I'm thinking about how we can build on it. Any thoughts and ideas on this from readers of this blog gratefully received!

Danny Cohen is controller of BBC Three