Pronunciation - The '/ɜ:/' Sound
The /ɜ:/ sound is a vowel sound. The : at the end of the sound means that it is a long vowel sound. In fact, some have people refer to the /ɜ:/ sound as the vowel version of the letter r. This is because the /ɜ:/ sound is always followed by the letter r.
Most students that are learning English have trouble with this sound. So what makes this sound difficult for so many? Well for starters, the /ɜ:/ sound is only native to English.