You have to be able to identify their sounds.
But not only by the ear, record your imitation and let yourself decide when you already say it.
Make the gestures you observe.

• With the buttons you can hear de sounds. And by compare them.
• With the button you can watch Youglish.com videos that include a word that contains the sound. Remember the facilities that it offers.
• With links to Merriam-Webster's you can verify the word.