Quick! What's the difference between these two words:

Calling a middle-aged lady, 「おばあさん」 will most likely be seen as an insult.

Calling an older, grandmotherly lady, 「おばさん」 will most likely be seen as a compliment.

長音 Long Vowels

Many Japanese words have long vowels. This is called:

長音(ちょうおん)

chou on

The word, 長音(ちょうおん), itself has a 長音(ちょうおん) sound. (Sorry, couldn't resist.) The う u sound makes the ちょ long.

• The long vowels do not add syllables: ちょ and ちょう are both one syllable.

• As a result, the vowel sound, usually, will sound the same, just held longer.
• The long vowels are about twice as long as a short vowel.

Rules for making longer sounds with Hiragana

For the most part, the following makes sense. The same vowel sound is pronounced twice as long and written with the hiragana that that sound represents. The last two, え and お, have a variation in the written form, however.

• For sounds ending in an あ a sound, add an あ:
  おばさん (aunt) → おばあさん (grandmother)

• For sounds ending in an い i sound, add an い after it:
  おじさん (uncle) → おじいさん (grandfather)

• For sounds ending in a う u sound, add an う:
  くこ (Chinese wolfberry 枸杞) → くうこう (airport 空港)

• For sounds ending in a え e sound, add either an え or い. While this can be confusing, just memorize which one as you learn vocabulary words.
  おねえさん (older sister; young lady お姉さん)
  へいき (calmness 平気 -or- military arms and weapons 兵器)

• For sounds ending in a お o sound, add either an お or an う. As with the え sound, you will just have to memorize these words. However, most of them use う.
  おき (open sea; okinawa 沖) → おおきい (big 大きい; notice this has two long vowels. お for the お sound and い for the き sound)
  とき (time 時) → とうき (porcelain; china 陶器)

Rules for making longer sounds with Katakana

This is much easier than hiragana. Instead of adding another vowel, simply add a dash after it. ー

コーヒー coffee

アパート apartment

バター butter