The word "piping down" refers to quietening or lowering one's volume. Some antonyms that can be used in place of piping down include "speaking up," "raising one's voice," "shouting," or "making a ruckus." In certain cases, it may be necessary to communicate more loudly or assertively, for instance, during an emergency or while leading a group. However, in most situations, it is advisable to practice good listening skills and to speak in a calm and thoughtful tone. Doing so can lead to better communication and more effective problem-solving. It is essential to choose the right words and tone for every situation.