The words that we write, read or say are made up of consonants and vowels. In the written alphabet the vowels are a, e, i, o, u and sometimes y. They are only 6 letters out of our 26, but they carry a lot of information. A vowel can stand alone as a word like I or A, but a consonant always needs a vowel.
You probably find consonants easier to pronounce than vowels. Let’s look at why that may be.
Consonants are produced by restricting the airway to some degree. For example the /t/ and /d/ sound are made when the tongue tip is placed behind the upper teeth, blocking the air and then the sound is made when the air is released. For the /b/ and /p/ sound the lips are closed and then opened. Additionally consonants may be voiced (vocal folds vibrate) or unvoiced. Place your hand on your throat and feel the difference when you say the /t/ and /d/ sounds.
So it is easy to see and feel the difference between the consonants.
Vowels are not so obvious to see or feel. They require less restriction of the vocal tract. Small changes in the tongue, lips, jaw and vocal folds that shape each vowel. These changes are hard to see as they occur in the mouth.
You’ve probably already realized that English spelling is not phonetic. This is especially true with vowels. The six letters that represent vowels are combined in our spelling to represent about 22 sounds. So the spelling of a word may not help you pronounce it.
Additionally, as discussed in this post, your native language may not contain all the vowel sounds of English, so this affects your ability to make this new sound.
For these reasons it is important to learn feel the vowels in your mouth.
The International Phonetic Alphabet (IPA) is a set of universal letter symbols representing a sound in speech. With the IPA words can be spelled phonetically. Follow this link to a site where you can “see” and hear the vowels. Listen and then say the words. Try to feel the changes in your mouth as you say the vowels.