Button with visually hidden text

index.html

<button>
  <span class="visually-hidden">Some text to announce</span>
  <!-- your icon or whatever -->
</button>

style.css

.visually-hidden {
  border: 0;
  clip: rect(0 0 0 0);
  height: auto;
  margin: 0;
  overflow: hidden;
  padding: 0;
  position: absolute;
  width: 1px;
  white-space: nowrap;
}