Upamsu Japa is prescribed in the texts of tantra in Hindu religion. It is the recitation of a mantra according to certain rules. Japa involves uttering the words of a mantra and applying the mind to the meaning of the mantra. There are different ways in which words of a mantra may be uttered. Accordingly, japa is classified into three varieties. They are
Vachika Japa – in which the words are uttered audibly. It is called also called the verbal japa.
Upamsu Japa – in which no audible sound is produced while reciting the mantra, but the words are uttered internally, involving movements of the lips, tongue, and the mouth.
Manasa Japa – in which the words are chanted purely internally.
When we produce sound by the vibrations of the vocal cords inside the throat, it is called a dhvani, which has no meaning or which is not a word belonging to any language. Language involves production of articulate sounds by specific movements of the apparatus of speech. It is called a varna, which has particular meaning. In Upamsu Japa, these movements of the lips, tongue, etc are gone through without the vibrations of the vocal cords. Thus Upamsu Japa involves less expenditure of energy, and in it the mind can be concentrated more easily and intensely.
The highest and most effective type of japa is Manasa Japa. In it there are no movements of the apparatus of speech. It is said in Mantra Yoga Samhita (64. 3-4) that in Upamsu Japa the words are heard by oneself but not by anyone else. In Gandharva Tantra (XVIII. 41 – 42), Upamsu Japa is said to be far more effective than Vachika Japa.