Learn Turkish: Başkan, yeni iddiayı hiç duymamış. - The president apparently didn't hear the new claim at all.

It combines the verb root duy (hear), the negative suffix -ma, and the reported past tense suffix -mış. The -mış ending shows that we did not witness this ourselves; we are reporting what we heard or inferred. Together, it means apparently he didn't hear.

Why is the reported past suffix -mış instead of -miş here?

Turkish suffixes change their vowels to match the vowel before them (vowel harmony). The negative suffix -ma has the vowel a. Under the 4-way vowel harmony rule, an a is followed by an ı, so the ending becomes -mış.

Why does iddia (claim) get the -yı ending to become iddiayı?

The -yı is the accusative case ending, which marks a specific direct object. Because the president didn't hear a specific thing (the new claim), we must use it. The y is a buffer letter because iddia ends in a vowel.

Why use hiç if the verb is already negative?

The word hiç means at all or ever. In Turkish, you use it alongside a negative verb to emphasize the negative meaning. So hiç duymamış means did not hear at all or never heard.