They are his tongue, by which he makes his knowledge articulate. 
ðeɪ ɑɹ hɪz tʌŋ, baɪ wɪtʃ hi meɪks hɪz nɑlʌdʒ ɑɹtɪkjʌleɪt. 
 Indian's voice is very clear in this recording, with monotone delivery and a moderate speaking pace. The sound is very close, suggesting a good or excellent recording quality.