High Quality Content by WIKIPEDIA articles! The voiced alveolar implosive is a type of consonantal sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is ?, and the equivalent X-SAMPA symbol is d_. The IPA symbol is lowercase letter d with a rightward hook protruding from the upper right of the letter. Its manner of articulation is plosive or stop, which means it is produced by obstructing airflow in the vocal tract.