Three Types of Japa Hari-bhakti-vilāsa, 17.155 – 158
trividho japa-yajñaḥ syāt tasya bhedān nibodhata vācikaś ca upāṁśuś ca mānasaś ca tridhā mataḥ trayāṇāṁ japa-yajñānāṁ śreyān syād uttarottaraḥ yad ucca-nīca-svaritaiḥ spaṣṭa-śabdavad-akṣaraiḥ mantram uccārayed vyaktaṁ japa-yajñaḥ sa vācikaḥ śanair uccārayen mantram īṣad auṣṭhau pracālayet kiñcic chabdaṁ svayaṁ vidyād upāṁśuḥ sa japaḥ smṛtaḥ dhiyā yad akṣara-śreṇyā varṇād varṇaṁ padāt padam śabdārtha-cintanābhyāsaḥ sa ukto mānaso japaḥ
[It is described in the Nṛsiṁha Purāṇa:] There are three types of japa-yajña. Listen to their respective names and qualities.
The three types are vācika-japa, upāṁśu-japa and mānasa-japa. Among these three, each is superior to the one before it.
Vācika-japa is chanting which is characterized by high and low pitches along with clear pronunciation and audible utterance.
Upāṁśu-japa is that in which the lips move slightly and the mantra is spoken softly in such a way that it is audible only to oneself.
Mānasa-japa is that in which the chanter mentally connects the syllables of the mantra to form a word and then mentally connects the words to form the mantra, thereafter meditating on the meaning of the mantra. Note: “Japa” in such contexts generally refers to recitation of gāyatrī-mantra and similar texts. The high and low pitches specified in this verse indicate japa of Vedic mantras and specifically gāyatrī.” Reciting prayers in pūjā is called stuti or stavana. — Translated by Hari Parshad Das from Śrī Hari-bhakti-vilāsaḥ with Bengali Translation, Bangabda 1318 (Corresponding to 1911 A.D.), edited by Shri Shyamacharan Kaviratn
above taken from Sri Krishna Kathamrita Bindu