The letter
, has running of sound (
), but imprisonment of the running of breath (
), making it similar to the
in these two aspects, except there is a small amount of air that is released with the letter
, even though they both have
.
The other characteristic that is important and solely present in the letter
is
, which linguistically means lengthening. In applied tajweed, this characteristic is: a pushing of the tongue from the back of the mouth to the front, until the tip of the tongue lightly touches the gum line of the two top front incisors, and this is under the influence of pressure of air behind the tongue. This lengthening is a mechanical pushing forward and the sound should not travel forward with the mechanical push, even though the sound of the
is influenced by the complete mechanism of
, the articulation point itself should not change. It is a common mistake among readers of all backgrounds to let the sound move forward with the mechanical move forward, in effect, changing the articulation point, and the sound of the letter
as a result of this error sounds more like a
and in some cases, if the tip of the tongue touches the edges of the front top incisors, it sounds like the letter
.
In Arabic language studies, the scholars mention many more characteristics of letters than are used in the study of tajweed. The reason is that most are not applicable to pronunciation, but more descriptive of the letter.