The sound of the conch is special. There is no stipulation that conch should not be sounded in south Indian temples. Even today it is a practice to sound conch at certain temples such as those in Kerala. Conch is sounded either when Perumal goes out in procession or when the doors of the temple are opened.
The statements of Thiruppavai – “tangaL tirukkOvil sangiDuvAn pOtandAr”, “veLLai viLi saning pEraravam kETTilaiyO”, also mean the sound of the conch. Two meanings are attributed to “sangiDuvAn”, one which means conch. As per “puLLaraiyan kOyil veLLai viLisangin pEraravam kETTilaiyO”, there is no harm in sounding the conch at temples.
But the reason why conch is not sounded at certain temples is due to the respect of those temples does not allow it. At temples where this is prohibited, we should not do as we please. Each temple follows its tradition and practices. At temples where conch is sounded, it is done so only through designated individuals. We must follow the tradition and practices of each temple.