ض  Articulation of 

1. Pressing Action 

During the articulation of ض, only the side edges of the tongue actively press against the inner surfaces of the upper molars. The front edge of the tongue makes contact with the roof of the mouth, but it does not apply pressure. This creates a shape similar to a spoon, where the sides are raised and engaged in pressing, while the tip is lightly touching.

This pressing action results in the formation of a sealed space or cavity above the tongue, where air becomes momentarily trapped.

2. Sliding Action

As the sound flows and begins to build up behind the tongue, it gradually pushes the tongue forward, resulting in a stretching of the tongue lengthwise. This unique forward movement is referred to as Istiṭālah (استطالة).

The stretching action further enlarges the space behind the tongue, facilitating the complete flow of the sound. This complete flow of the sound is known as Rikhāwah (الرخاوة)—a property that describes the nature of the sound flow of the letter ض when pronounced correctly.

Conclusion 

Mastering the articulation of ض requires careful attention to both the pressing of the tongue’s sides and the flow of sound that causes the tongue to stretch forward. Together, these actions define the letter’s unique sound and distinguish it from all other Arabic letters. Understanding this mechanism aids in correct pronunciation of this unique letter.