Ivan Berdinsky
--- a/core/misc/cspell/dictionary.txt
+++ b/core/misc/cspell/dictionary.txt
 schemaapi
 schemeless
 scorewords
+screenreaders
--- a/core/lib/Drupal/Core/Render/Element/RenderElementBase.php
+++ b/core/lib/Drupal/Core/Render/Element/RenderElementBase.php
      }

+      // Set default values for progress' screen reader properties.
+      // The 'announce' property determines if screenreaders should announce
+      // progress for this operation.
+      // The 'announceDelay' property is how many milliseconds must pass before
+      // AJAX progress is announced by a screen reader. This prevents announcing
+      // operations that are completed quickly enough that an announcement is
+      // not necessary or useful.
+      // The 'announceIntervalTime' property is how many milliseconds must
+      // pass before the operation is re-announced. This provides a way to
+      // distinguish an operation in progress vs an operation that did not\
+      // complete.
+      // The 'announceMessage' property is what is used if no 'message'
+      // property is present.
+      if (isset($settings['progress'])) {
--- a/core/misc/ajax.js
+++ b/core/misc/ajax.js
      typeof this[progressIndicatorMethod] === 'function'
    ) {
      this[progressIndicatorMethod].call(this);
+
+      // To avoid very fast AJAX operations from being announced, wait for the
+      // duration of the announceDelay property (1 second by default) before
+      // announcing progress to screenreaders.
+      const delay = this.progress.announceDelay || 1000;
+      setTimeout(() => {
+        // Note that the disabling of $(this.element) is a pre-existing
+        // implementation used to prevent interaction while the request is in
+        // progress. It is being leveraged here as a way to confirm the AJAX
+        // operation completed as nothing else is available in scope to do so.
+        const shouldAnnounce = this.progress.hasOwnProperty('announce')
--- a/core/modules/system/tests/modules/ajax_test/src/Form/AjaxTestForm.php
+++ b/core/modules/system/tests/modules/ajax_test/src/Form/AjaxTestForm.php
      '#markup' => '<p>' . $this->t("Ajax Form contents description.") . '</p>',
    ];

+    $form['select'] = [
+      '#type' => 'select',
+      '#title' => 'AJAX Select field',
+      '#options' => [
--- a/core/misc/ajax.js
+++ b/core/misc/ajax.js