def speech_speaker(self):
        """Retrieves the speaker of the audio or video file associated with the element.

        The source is inherited from ancestor elements if none is specified. For this reason, always use this method rather than access the ``src`` attribute directly.

        Returns:
            str or None if not found
        """
        if self.speaker:
            return self.speaker
        elif self.parent:
            return self.parent.speech_speaker()
        else:
            return None
Retrieves the speaker of the audio or video file associated with the element.

        The source is inherited from ancestor elements if none is specified. For this reason, always use this method rather than access the ``src`` attribute directly.

        Returns:
            str or None if not found