Final answer:
The Silencing Charm, also known as the Muffliato Charm, does not cause an increase in volume of voice when miscast.
Step-by-step explanation:
The Silencing Charm, also known as the Muffliato Charm, is a spell used in the Harry Potter series to prevent others from hearing a conversation. It creates a buzzing noise in the ears of those nearby, thus making it difficult for them to hear what is being said. Therefore, increased volume of voice is not a side effect of a miscast Silencing Charm.