Is there a rule to know how 'ch' may sound?

Sorry to be the bringer of bad news.

There are no 100% ( often not even 90%) rules for English pronunciation. The only way to be sure, even for native speakers who didn't hear a word before, is to look it up in a dictionary with phonetics, or ask a competent native speaker.

This is one of the biggest hurdles for learners who are accustomed to the same letters (nearly) always sounding the same in their native language. Imagine written English somewhat like Chinese pictograms, where there is at best a very tenuous link between the sign and the word. After you stop looking for rules and accept the facts of life you'll feel much better. ;-)

Sorry to confuse you even more, but if the word is of late French adoption, the 'ch' is usually pronounced like English 'sh' - 'like machine.' If you had told us what your first language was, I may have been able to give more help. Pronunciation is notoriously difficult to get across in Y!A.

The big problem with English pronunciation is that there are at least 44 phonemes and something over 60 allophones if you count the positional variants of some of these, so it is very difficult to represent these sounds with an alphabet of 26 letters.

Unfortunately, there is no rule on how ch should be pronounced. Modern English is a conglomeration of many language roots (Latin, Greek, Germanic, etc.). All of these different strands pronounce ch differently.

I would recommend reading along with a book on tape, so that when you see the word, you also hear it. This method is effective with my students who have reading difficulties, or those who English is their second language.

Another method you could try would be to keep a dictionary by you when you are reading. Many dictionaries have the pronunciation included with the definition.

I hope these methods are helpful to you. Good luck on learning English. It is a difficult language because of the lack of rules that other languages have.

It really depends on the origin of the word and the position of the 'ch' in the word, whether it be and the start, the middle, or the end. Also it depends on the dialect being spoken.

There are patterns but what I would suggest is looking the words up in a dictionary and learning IPA or X-SAMPA so you can read the symbols shown in the dictionaries.

Some times the 'ch' in "chocolate" can sound like the 'ch' in chip or the 'sh' in shock. In the word "loch" the 'ch' is very gutteral but in "monarch" it's pretty clear. The 'ch' in "ache" is similar to that in "monarch".

Really though you should look in a good dictionary, listen to the radio and learn IPA and X-SAMPA. :-)

http://en.wikipedia.org/wiki/Ipa

http://dictionary.reference.com/

http://en.wikipedia.org/wiki/X-sampa