Announce changes with LiveAnnouncer

live-announcer.component.ts

import { LiveAnnouncer } from '@angular/cdk/a11y';
import { Component } from '@angular/core';

@Component(...)
export class ColorPickerDialogComponent {
  color = '#fff';
  public defaultColors: string[] = [...];

  constructor(private liveAnnouncer: LiveAnnouncer) { }

  public changeColor(color: string): void {
    this.liveAnnouncer.announce(`Select color: ${color}`);
  }
}