In this week's Mailbox we answer your letters and emails about the future of our Czech language series ABC of Czech, a man we recently reported on who composes music by listening to mushrooms and the complicated question of how many people listen to Radio Prague.

We've had a few letters and emails about the end of our Czech language series, which Pavla Horakova has been presenting since it began in April 2002. John Riehs wrote to us saying he couldn't believe his eyes when he read the Czech language series was being discontinued, and asked if there would be any other such features which would help people like him learn the Czech language. That's a question we put to Pavla Horakova herself.

"Our Czech language series went on for 19 months and we thought that we should give you the listeners a break. Those of you who'd like to listen to it again have a chance, as we'll be running the series all over again, starting this Sunday. You'll also find all our Czech lessons on our website in sound and text, as well as an older series called Living Czech, written and presented by Nick Carey. And as we've had mail coming in from our listeners expressing regret over the end of the ABC of Czech, we're thinking about putting it back in our programme sometime soon. In the meantime, I'll be thinking of what its topics will be."

Moving on, David Williamson of Sussex in the United Kingdom says he heard a report on Radio Prague recently about Vaclav Halek, a man who composes music after listening to mushrooms growing in the forest. Mr Williamson asks "is that man for real? If so, I'd really like to know more about him - is he a total eccentric?" Rob Cameron was the one who interviewed him. Rob, what is Mr Halek really like?

"He is for real. I can confirm that because I spent about a day with him in the forests near Prague. He is slightly eccentric, that cannot be denied, but it has to be said he is also hugely talented. He is after all a respected composer, he's composed more than 2,000 pieces of music, he's composed film scores, theatre scores.

I actually looked him up on the internet and found that he is fairly well known in musical circles as a composer. Obviously what he does, he claims he can hear mushrooms singing, does make him eccentric but when you listen to the music he produces, inspired by this, he's obviously not completely mad; he does hear something, it does inspire him."

How old is Mr Halek?

"I'd say he's in his late 60s, he is getting on a bit but he's still fairly energetic, he goes mushroom-picking regularly and also he does have a lot of time for composing, because he's a very prolific composer."

Next we've had a few emails and letters asking how many listeners Radio Prague has around the world, and how do radio stations know how many people listen to their broadcasts. Radio Prague's editor-in-chief David Vaughan is the man to ask that one.

"Basically, the answer is we don't know. What we do know, of course, is the number of people who visit our website. That figure is rocketing, at the moment; in the last couple of years it's increased by several hundred percent, and currently the number of individual visits to our website per month is just under 300,000.

As for listeners who listen to us as traditional radio, we don't have a formula to calculate the number of listeners we have. Various formulae do exist, but they're not entirely reliable. We get annually around 15,000 letters, which is to all our different language sections. That's a tiny fraction of the number of people listening to us; one thing all people involved in radio research agree on is that most listeners don't write.

Also, it's getting more and more difficult to measure the number of listeners we have, given that we have so many different platforms that we broadcast on, for example through other stations. Many people will hear us on for example FM in Slovenia, if they listen to Insight Central Europe. So, it's a tough one. And we're always having to persuade politicians, who finance us, that it's not actually possible to come up with a concrete audience figure."