Answer found

But it's only available in these languages:

• English (United States): What are audiotracks?
• Italiano: Cosa sono le tracce audio?
• Français: Que sont les pistes audio ?
• Deutsch: Was sind Tonspuren?
• Español: ¿Qué son las pistas de audio?
• Chinese (Sim.) (简体中文): 什么是音频轨道
• Português: O que são faixas de áudio?