<ul class="menu">
  <li>Sound 1</li>
  <li>Sound 2</li>
  <li>Sound 3</li>
  <li class="active">Sound 4</li>
  <li>Sound 5</li>
</ul>

.menu li {
  cursor: pointer;
}
.menu li.active {
  background-color: #fc6;
}

const ul = document.querySelector('ul.menu');
const listItems = ul.querySelectorAll('li');
const onClick = ({ target }) => {
  const li = target.closest('li');
  listItems.forEach(el => el.classList.toggle('active', el === li));
};
ul.addEventListener('click', onClick);