loud 1、adj.(-er,-est) 喧闹的; 响亮的:loud voices,screams,laughs,etc 宏亮的嗓音、 喊声、 笑声等 * That music's too loud; please turn it down.那音乐太吵人了; 请把音量调低些.
2、adv.(-er,-est) 尤与talk、 sing、 laugh等动词连用:laugh loud and long 大笑不已 * Speak louder I can't hear you.大点声说--我听不见.
aloud
adv.出声地（用足以使人听得到的声音,既非默不作声地亦非悄悄声地）:He read his sister's letter aloud.他喃喃地读他妹妹的信.
大声地,高声地（使得在远处也听得见）:She called aloud for help.她高声呼救
loudly
adv.高声地；响亮地She screamed as loudly as she could.
sound n.1、[U] 声; 声音:Sound travels more slowly than light.声速低於光速.
2、[C,U] 声音; 声响:* I heard a strange sound outside.我听到外面有一种奇怪的声音.* He crept upstairs without a sound,ie noiselessly.他悄悄地上了楼.