The communicative approach is based on a very interesting idea. A strong point of the communicative approach is that it focuses on the student's ability to transmit ones ideas in the target language, in this case English and Dutch.
Unfortunately, the way it is often interpreted and implanted, in my opinion, doesn't quite have the result one could expect. All to often it is interpreted as: "If the teacher understands what the student says, we have communication. Great!" Problem with this interpretation is that teachers from the same region as the students, understands the students' mistakes all to easily because they are used to the typical mistakes and errors resulting from influence from the first language. This reduces the student teacher interaction to an imitation of communication.
In the beginning of my teaching career in Belo Horizonte, Brazil, I saw how this can be a problem. I asked on of my students of intermediate level if next class he would bring his book. His response sounded to me like: "ah wuw" . I had no idea of what he wanted to say. Another student had to tell me he wanted to say: "I will" . The fluency of the student in case indicated no further lack of practice in 'communicating' in English. Apparently previous teachers had always accepted this pronunciation.
This case in particular lead to the idea to always simulate to be a normal user of the target language, pretending not to understand errors like those that are typical of first language interference.
As a teaching method a mere imitation of normal communication is far from enough, one should use good simulations of real life communication.
Communication problems do not only result from vocabulary or idiomatic errors. Pronunciation errors can also cause communication problems. A good illustration is an anecdote I got as feedback from a student whom, I had taught the correct pronunciation of the 'l' sound at the end of a syllable and the importance if this, like in "I will". Something difficult to learn for Brazilians.
One day, during the time my student was attending course in Sweden, he and a friend, both Brazilians, went to a bar. When they wanted to pay, the friend asked the waiter what sounded like: "Two biws, please." A bit later, the waiter came back with two beers . This reminded my student of what I told him about the pronunciation of the 'l' and asked for "two bills" . The waiter said sorry, took the beers back and brought them their separate bills.
Now, if they had known the standard expression: "separate bills" and only had pronounced it wrong, probably the waiter would have understood them, just like she understood them when my student only corrected the pronunciation. Making both mistakes, pronunciation and idiomatic, led to misunderstanding.
What is important in communication is if any regular user of the target language, can understand the language produced by the person in question, the learner. This is were well designed simulations come in. A good communication teacher should, as a first reaction, pretend to only understand what can be expected that any user of the target language would understand and react accordingly. This lead to the simulation principle: "Give'm what they ask for."
To hear the sounds that go with these symbols from the International Phonetic Alphabet, visit these IPA charts from York University. Klick two times on a chart to open it and then klick on a symbol to hear a recording of the corresponding sound. The IPA version used on this site is from 1993, updated 1996. Last update at the International Phonetic Association is from 2005.
Basically, I don't tell students what's wrong, I show what's wrong. I react according to what the students say, not according to what they want to say (even though, very often, I have quite a good idea of what it is). One result is that, rather than feeling corrected, students get surprised because my reaction is different from what they expected. They conclude that something went wrong. Apparently I didn't understand what they wanted to say.
Other aspects of the learner's behaviour should be dealt with as well. One can't overlook cultural differences such as standards of politeness and other aspects of behaviour. A language is a communication tool. The communication tool of a certain people with a certain culture. If one wants to speak with people, communicate with them and have good contact, only knowing their language is not enough. One has to know at least that much of their culture, especially of their rules of politeness, as not to cause unpleasant situations.
Details about phonetics can be found at the official site of The International Phonetic Alphabet (IPA)