He stuck out his tongue and licked the ice cream.

Back vowels are vowels that are pronounced using the back of the tongue.

A back vowel is a sound where the back of the tongue approaches the palate.

A front vowel is a vowel that is articulated with the front part of the tongue.

The central vowels in Japanese are 'a', 'e', 'o'.

A central vowel is a vowel that is pronounced in the central part of the tongue.

Front vowels are pronounced using the front part of the tongue.

In this old document, the usage of vowels is different from today.

He stuck out his tongue and licked the ice cream.

There are five monophthongs in Japanese.