Mantra is a very important part of tantra. The complete practice of Tantra cannot exist without mantra. 
In the beginning of evolution there was a big explosion in the sound of AUM. This is the cosmic sound. From this cosmic sound, 50 other matrikas, mothersounds, arose. From this 16 vowels and 34 consonants were formed; the birth of the Sanskrit alphabet. These matrikas shaped themselves in the human body in the form of chakras. Each chakra has a different amount of lotuspetals with one matrika on each petal.

Languages like English are there to communicate with each other. There is no reason why a tree is called ‘a tree’. However, in Sanskrit everything is mantra and there are formulas that proof why certain sounds have to be created. Same goes for the names of the different gods and the mantras that are used to invoke them. The names are not just invented by the human mind, they could not be otherwise. Once chanted, they have different effects on the inner being and external cosmos. With the chanting of mantra you are not just invoking something outside of yourself, but rather you are bringing something to the surface that is already within you.

Mantras go beyond grammar and meaning, it is all about sound vibration. Since it is about sound vibration, the correct pronunciation is of upmost importance. Therefore, for the one that wants to deepen his mantra practice, it is essential to study Sanskrit.

“Shiva knew as much of Sanskrit as a drop on a blade of grass. When you shake this blade of grass and the drop divides and spread itself in thousands different directions, Panini, the composer of the Sanskrit alphabet and grammar knew as much as one of those tiny parts. Sanskrit is the sound vibration of the universe and impossible to be mastered with the limitations of the human mind.”

The individual mind is connected to the cosmic mind. This force of mantra affects a certain part of the universe and creates ripples in the cosmos, similar to that of electromagnetic or radio waves. It has its own field where it travels. There are numerous types of wave patterns and frequencies. They are like layers of sound vibrations.  Mantras that are produced with full concentration have a higher frequency, but if the mind is dissipated then the frequency is low. This higher frequency transforms the universal area of the mind and becomes a vehicle to communicate with the cosmic mind. Then the barrier between an individual and the universal mind breaks down. The individual mind becomes the universal mind: totally pure and deeply connected to the essence of existence. That is the power of sound vibration that has been discovered by yogis throughout the ages.

Mantra is the most important aspect of yoga! Stretching and breathing without mantra is of no benefit.
Why are people always reciting all scriptures and old texts? Because it is the sound vibration itself through which you connect to higher frequency! Not many people who read Sanskrit know all about what it means. Of the Vedas there is little to no understanding at all. It is not even important to understand everything and know what the words mean, it cannot be grasped by the mind.

What is important is the effect that it has on the subtle layers of your being. It is through this frequency that you can connect to the higher consciousness.

Mantra is like phoning with God and higher dimensions. The mala is the phone device.