These are the five elements, mind, ego and nature that are embodied in the different aspects of puja. Without this inner recognition service or ritual remain mechanical and ineffective. Note that yogic asanas come under ritual as a form of bodily practice. Better than loud chanting of mantras, is the soft muttering of them, best is their mental repetition. This verse explains mantra yoga that deals with speech, which is usually the next stage after karma yoga that deals with the body.
Mantras take three forms.
Loud chanting helps us imbibe the basic quality of the mantra. Soft muttering of mantras connects them with the breath. Mental repetition, in which they come to reverberate in the subconscious mind, has the strongest transformative effect. Practicing mantras in these three stages and holding them at the third stage is the best. The Ramanashram, since Ramana's time, has always held daily Vedic chanting for its power to calm and purify the mind.