• ج (jeem) makes the "j" sound as in "Jack" or "John". With a good Arabic accent it sounds slightly different than the English version of this sound.

• ح (Hžaa) makes a non-English sound. People not good at Arabic pronounciation confuse it with the sound that the letter ه (haa) makes. This is because they sound similar. They are different. ح (Haa) is a more frictive version. All Arabs pronounce this properly; mispronuncing this letter will make your Arabic very difficult to understand. Never pronounce it the same as خ (khaa). Some beginners make this mistake .

• ع (`ayn) makes a non-English sound. Non-Arabs confuse it with ء (hamza) (hamza makes the glottal stop). They are different. ع (`ayn) is the voiced version of ح (Haa). It is NOT a voiced glottal stop (some books mistake it to be). Mispronouncing this sound will make you incomprehensible in Arabic.

• خ (khaa) makes a non-English sound. Many languages have this sound. German has it in the "ch" in "Bach", Russian has it in the "ch" of Rachmaninoff, and Scottish English has it in the "ch" of "loch." It is similar to the sound people make when preparing to spit.

• غ (ghain) makes a non-English sound. It is the voiced version of خ (khaa). It is the sound everyone makes when they gargle water.

Reference