15 Definitions: Japa, Kirtana, Sankirtana, and Sravana
The difference between japa and kirtana:
When a mantra or hymn is chanted softly and slowly, that is called japa. The same mantra, when chanted loudly, is called kirtana. For example, the maha−mantra (Hare Krsna, Hare Krsna, Krsna Krsna, Hare Hare/ Hare Rama, Hare Rama, Rama Rama, Hare Hare) when uttered very softly only for one's own hearing is called japa. The same mantra, when chanted loudly for being heard by all others, is called kirtana. The maha−mantra can be used for japa and kirtana also. When japa is practiced it is for the personal benefit of the chanter, but when kirtana is performed it is for the benefit of all others who may hear. In the Padma Purana there is a statement: "For any person who is chanting the holy name either softly or loudly, the paths to liberation and even heavenly happiness are at once open."
– The Nectar of Devotion
The meaning of kirtana and sankirtana:
The chanting process offered by Lord Caitanya for achieving love of God is called sankirtana. Sankirtana is a Sanskrit word. Sam means samyak "complete." And kirtana means "glorifying" or "describing." So complete description means complete glorification of the Supreme, or the Supreme Complete Whole. It is not that one can describe anything or glorify anything and that will be kirtana. From the grammatical point of view that may be kirtana, but according to the Vedic system, kirtana means describing the supreme authority, the Absolute Truth, the Supreme Personality of Godhead. That is called kirtana.
This devotional service begins with the method of sravana. Sravana means "hearing," and kirtana means "describing." One should describe, and another should hear. Or the same man himself can both describe and hear. He does not need anyone else's help. When we chant Hare Krsna, we chant and hear. This is complete. This is a complete method. But what is that chanting and hearing? One must chant and hear about Visnu, Krsna. Not of anything else. Sravanam kirtanam visnoh: [SB 7.5.23] one can understand Visnu, the all−pervading Absolute Truth, the Supreme Personality of Godhead, by the method of hearing.
– The Science of Self Realization
Definition of sankirtana:
When a person loudly chants the glories of the Lord's activities, qualities, form, etc., it is called sankirtana. Sankirtana also refers to the congregational chanting of the holy name of the Lord.
– The Nectar of Devotion
Definition of sravana:
The nine processes of devotional service are as follows:
1. [sravana] hearing the name and glories of the Supreme Personality of Godhead.
2. chanting His glories
3. remembering the Lord
4. serving the Lord's feet
5. worshiping the Deity
6. offering obeisances unto the Lord
7. acting as the Lord's servant
8. making friends with the Lord
9. surrendering oneself fully to the Lord
– The Nectar of Instruction Text 3