code: private void deliverTempoChangedAnnouncement(final double tempo) {
          for (final MasterListener listener : getMasterListeners()) {
              try {
                  listener.tempoChanged(tempo);
              } catch (Throwable t) {
                  logger.warn("Problem delivering tempo changed announcement to listener", t);
              }
          }
      }
docs: Send a tempo changed announcement to all registered master listeners.
  
  @param tempo the new master tempo