To understand this tidbit lesson, please make sure you have read and understood the two lessons on the mechanism for articulation of  letters (lessons 14 and 15 from the top of the archive page), located in the tidbit archive section.  

Letters other than the three medd letters which have no vowels are produced by collision ( ) of the two components of the articulating parts Voweled letters on the other hand are produced by parting of the two components of the articulating parts 
( ).  The medd and leen letters are produced by vibration of the vocal cords.  Letters are divided into three groups when categorized according to the length of running of their sound.

   1.      Letters of strength ( ).  The sound does not run at all when these letters are articulated without a vowel (saakinah), the articulation point is completely closed when a letter of this group is saakin.  There are eight letters in this group.  They are the letters in the phrase: or as stated in the Jazariyyah prose:

, meaning its [letters of] strength are in the phrase .  

   2.      Letters in Between. ( ) These letters are pronounced with sound running in between the characteristic of imprisonment in the  letters and the running of sound in the  letters.  The letters of this group are five in number:
. 

   3.      Letters of softness ( ) These letters have clear and obvious running of the sound when they are articulated without a vowel (saakinah).  Examples are in the following three saakin letters that are in the category of : . Each of these three letters in the example should have a running of the sound, longer than saakin letters of the other two groups  The letters of this group are all the letters remaining when taking out the letters of  and .

The Qalqalah

The letters of qalqalah are in the group , these letters are all in the  group of letters.  If we attempt to say one of these five qalqalah letters with a sukoon, we would find that the articulation point closes completely, and that it causes an annoyance in the articulation mechanism.  This is due to imprisonment of the sound behind the articulation point. When these same five letters have vowels, we do not find this annoyance because voweled letters are pronounced parting of the two components of the articulating parts
( ).  The Arabs, due to the annoyance and difficulty in pronouncing these five letters when saakinah, have violated the rule that saakinah letters are articulated by collision between the two articulating bodies of articulation, ( ).  Instead, these letters are articulated by separation of the two articulating parts of articulation ( ), the same as voweled letters, but without any corresponding movement of the mouth and jaw that is associated with voweled letters.

Chart comparing the  to voweled letters  and non-voweled letters

From this chart we can see that a qalqalah letter is similar to a saakin letter, in that there is no accompanying jaw and mouth movement with it.  On the other hand, it is unlike the saakin letter in that the qalqalah is articulated by separation 
( )of the two parts of articulation.  The qalqalah letter is similar to the voweled letter since they both are articulated separation 
( ) of the two parts of articulation, but unlike it since the qalqalah has no accompanying jaw and mouth movement and the voweled letter does. 

The definition of qalqalah is as follows:

Its linguistic definition: shaking, disturbance

Its applied definition: Disturbance of the letter when it is in the state of being non-voweled until a strong accent is heard when it is articulated by parting of the two components of the articulating parts, not by collision, without accompanying it any opening of the mouth, or circling of the lips, or lowering of the jaw. 

A very important note: The qalqalah does not resemble a fat-h or a dhammah or a kasrah.  It does not follow the vowel of the preceding letter, nor the following letter.  

If the qalqalah letters have a shaddah indicating merging of two of the same letter ( ), the first letter of the shaddah (which is saakin) is then articulated by collision, or .  For example: and .  If we are stopping on the first word in the previous example, the first  of the word  is pronounced by collision, or , and the second  is recited with a qalqalah.  This means that the qalqalah is pronounced with  without any accompanying mouth and jaw movement.  The  of the word  would be the same as the  in the word . 

The Qalqalah is divided into two classes: The Lesser and Greater Qalqalah

The Lesser Qalqalah : This occurs when  the qalqalah in is the middle of a word, or at the end of a word, and we are not stopping on that word. In this case we say the qalqalah, and immediately proceed to the next letter, or word. i.e. and

The Greater Qalqalah : This happens when the qalqalah is the last letter of a word, and we are stopping on that word.  For example: .

The difference between the two divisions is that there is more of a ring to the greater qalqalah because we are stopping on it, than there is on the lesser qalqalah.