Satsang – sat + sang.
Sat means the Truth. Sang means – in company of.
Satsang means to be in company of someone who has realised truth. Someone who has achieved self-realisation. In the right meaning Satsang includes anything that happens in the presence of our sadguru or a Paramhansa. It can be chanting of mantras, it can be bhajans, it can be discourses, or it can be total silence too. Whatever happens in the presence of Sat is Satsang.
Since we are physically away from our sadguru we seek his/her presence in shaktiswaroopa(energy). Or sukshma swaroopa(invisible form). With this belief we do our chanting. Or Aarti or other rituals as advised by our Guru Parampara(Lineage of Gurus). By doing this we invoke their blessings which cleanses, purifies our body, mind and soul. We receive divine positive energy which can definitely be experienced through subtle changes in our thoughts and our behaviour.
Chanting a mantra aloud is a multiple process. Before we utter those words we create them mentally. The second step is actually singing or speaking those words. Third is listening those words/mantras sung by us as well as others. Mantra is not any simple word or a mixture of alphabets. These words are energized by our sadguru by their own efforts. Hence we should not chant any mantra which may come across. Chanting is fruitful only if that mantra is given to us by our sadguru. Thus there is a triple effect of these chants: one is inside our mind, second effect emanates through our throat as well as our mouth, and third effect is through our ears while listening. This regular inward and outward flow of mantra in our human body affects us positively . Harmonium, tabla, dholak, cymbals are the desired accompaniments because God Dattatreya is very fond of them. God Dattatreya is Bramha, Vishnu and Shiva personified in a single form (Avatar).
Chanting is done aloud not to attract anybody’s attention but because whichever living being, be it humans, animals, plants, trees, birds, insects, micro organisms, comes in the vicinity of the audio waves is affected by them. Thus the entire environment is purified as well as energized. This is the simple reason why our temples, ashrams, and other religious places are spiritually vibrant.
This in short is the importance of chanting.