The word 传声筒 is formed by combining the characters 传 (transmit), 声 (sound), and 筒 (tube), resulting in a literal compound meaning "sound-transmitting tube". This directly describes a physical object, such as a megaphone or speaking tube, where 传 indicates the action of conveying, 声 specifies what is conveyed, and 筒 denotes the cylindrical shape that facilitates the transmission.