Besides the vowel harmony rules, there are other basic rules that affect the way suffixes are used. A vowel following another is never allowed in Turkish, and there are rules to avoid these situations when they occur as a result of other rules. There are also rules about consonant harmony, that make some consonants change in certain cases.

2. Consonant Harmony

Vowel harmony rules cause the vowels of suffixes to be modified when they are added to some words. There are similar rules about consonants. However, you may feel that all these rules are too many just for a simple start. Then, I advice you to omit the consonant harmony rules when you want to say or write something, just for the start. You will still be understood. Consonant harmony is mainly for making speech more fluent, it does not have a major effect on understandability. You will eventually learn these if you decide to continue learning Turkish, as you read sentences or listen to Turkish speakers.

There are two cases consonant harmony takes affects:

The trouble making consonants in this case are 'p', 'ç', 't' and 'k'. Whenever a word ends with one of these consonants and you want to add some suffix to that word, stop there and think twice. Try to find a different way of expressing your thoughts. If you can't do that, if you really need to use that word and add a suffix to it, then follow the guidelines I will present now:

Let's call the words that end with one of 'p', 'ç', 't' or 'k' the trouble words. But be careful, this is not an officially used term.

CASE A - Word mutation.

Two conditions must be satisfied for word mutation to occur:    

1. You have a word ending with one of 'p, ç, t, k'.

2. You want to add this word a suffix that starts with a vowel.

If the word has only one syllable, like saç, you are safe. The word does not change.

saç-ı --> saçı

sap-a --> sapa

However, if the word has more than one syllable, than the consonant at the end changes.

• p becomes b
• ç becomes c
• t becomes d
• k becomes ğ

And here are some examples to this:

ağaç-a --> ağaca (to the tree)

şarap-ın --> şarabın (of the wine)

kağıt-a --> kağıda (to the paper)

geyik-e --> geyiğe (to the deer)

CASE B - Suffix mutation.

Two conditions must be satisfied for suffix mutation to occur:

1. You have a word ending with one of 'p, ç, t, k, f, h, s, ş'.
2. You want to add this word a suffix that starts with 'c' or 'd'.

In this case, the first letter of the consonant changes.

• c becomes ç
• d becomes t

 Examples to this would be:

Leh --> Polish (people)

Leh-ce --> Lehçe --> Polish (language)

Türk --> Turkish (people)

Türk-ce --> Türkçe --> Turkish (lanuage)

yap --> do

yap-di --> yaptı --> he did