您可以将isMuted，monster和audio变量移动到DOM的属性中。因此按钮将保持其状态（开/关），以及相应怪物和音频的名称。
创建怪物和音频的Map，属性名称对应变量。然后调用setButtonAttributes将音频和怪物的名称设置为按钮属性。
重要的是，在buttons数组中保存DOM对象，您可以使用document.getElementById("BUTTON_ID")，document.getElementsByTagName("button)等方法获取它们。

let buttons = [...] // here enumerate all your buttons
let monsters = {
    monster1: monster1, 
    monster2: monster2,...
} // keep your monster variables in a map
let audios = {
} // audios' map similar to monsters' one

for(let button of buttons) {
    button.onclick = () => muteMonster(button)
}

function muteMonster(button) {
    let monster = monsters[button.getAttribute("monster")]
    let audioElement = audios[button.getAttribute("audio")]
    if (!button.getAttribute("isMuted")) {
        button.setAttribute("isMuted", true);
        monster.style.opacity = "0.5";
        audioElement .muted = true;
    } else {
        button.setAttribute("isMuted", false);
        monster.style.opacity = "1";
        audioElement.muted = false;
    }
}

setButtonAttributes() {
    let iter = 0;
    for(let button of buttons) {
        button.setAttribute("monster", `monster${iter++}`)
        button.setAttribute("audio", `audio${iter++}`)
    }
}

setButtonAttributes()

这里有一个方法来填充你的数组与正确的值（所有=真在开始）为您的布尔数组，在怪物数组的引用...
最后一个函数function resetToTrue(index)更新布尔数组，并避免有多个怪物未静音。
注意：如果你不想看到你的按钮上的日志，当你运行代码片段时点击“完整页面”，否则它们将无法点击！
祝你今天愉快

let nbElements = 7;
        let monsters=[];
        let buttons=[];
        let isMuted=[];
        window.addEventListener("DOMContentLoaded",createTables);
        function createTables(){
            for(var i = 0; i < nbElements; i++){
                monsters.push(document.getElementById("monster_" + (i+1)));
                buttons.push(document.getElementById("button_" + (i+1)));
                isMuted.push(true);
                monsters[i].textContent = "monster n°" + (i+1) + " muted = " + isMuted[i] + " audio_" + (i+1) + " = " + !isMuted[i];
                monsters[i].style.opacity = 0.5;
                buttons[i].addEventListener("click",buttonClickHandler);
            }
        }
        function buttonClickHandler(e){
            isMuted[this.value-1] = !isMuted[this.value-1];
            monsters[this.value-1].textContent = "monster n°" + this.value + " muted = " + isMuted[this.value-1] + " audio_" + this.value + " = " + !isMuted[this.value-1];
            
            resetToTrue([this.value-1])
        }
        function resetToTrue(index){
            for(var j = 0; j < nbElements; j++){
                if(isMuted[j]==false){
                    isMuted[j]=true;
                    isMuted[index]=false;
                }
                monsters[j].textContent = "monster n°" + (j+1) + " muted = " + isMuted[j] + " audio_" + (j+1) + " = " + !isMuted[j];
                if(isMuted[j]){
                    monsters[j].style.opacity = 0.5;
                }else{
                    monsters[j].style.opacity = 1;
                }
            }
            console.log("isMuted Array = " + isMuted);
        }

<div id="monster_1">monster</div>
    <div id="monster_2">monster</div>
    <div id="monster_3">monster</div>
    <div id="monster_4">monster</div>
    <div id="monster_5">monster</div>
    <div id="monster_6">monster</div>
    <div id="monster_7">monster</div>
    <button id="button_1" name="button_1" value="1">button_1</button>
    <button id="button_2" name="button_2" value="2">button_2</button>
    <button id="button_3" name="button_3" value="3">button_3</button>
    <button id="button_4" name="button_4" value="4">button_4</button>
    <button id="button_5" name="button_5" value="5">button_5</button>
    <button id="button_6" name="button_6" value="6">button_6</button>
    <button id="button_7" name="button_6" value="7">button_7</button>

如果多个怪物可能被“取消静音”，只需在函数resetToTrue()中注解这些行，如下所示：

/*
if(isMuted[j]==false){
    isMuted[j]=true;
    isMuted[index]=false;
}
*/