The hardest sound in English?

What is the hardest English sound for you? 

I'm curious about how different languages perceive English sounds and what are the sounds that do not exist in your mother tongue. 

Pronunciation learning and practicing

For those learning English as a foreign language, how do you practice pronunciation? 

 

Are there any particular exercises or tricks that you find helpful when practicing pronunciation and would you like to share them?

 

Teachers, I'm curious about your oppinion also. How do you teach pronunciation? How important do you think it is in ESL teaching? 

 

 

First notebook entry: Introducing myself Trabajo por una empresa que creado a un software para aprendir pronunciación de American Ingles. Queria ayudar la gente practicar mi idioma y recommendar nuestra aplicación Saundz. Ademas, queria mejorar mi español y talves aprender una idioma nueva.