A swinging bell striking twice: a higher note on the way over, a lower note on the way back, and then again. One way to hold the word is that back-and-forth — two things taking turns, loudly, with neither one settling. The bell is the sound itself; voices in a row take turns the same way; so does the lead in a close game.
可以想成一口鐘被推著來回擺。過去敲一下，是高的 ding。回來再敲一下，是低的 dong。兩下輪流，停不下來。這個「一來一往、還很大聲」的畫面，可以拿來看 ding-dong 的幾個用法。鈴聲本身就是那個畫面。兩個人吵架，你一句我一句，也是那個節奏。比賽裡領先權換來換去，一樣是來回。
From the word’s history
Wiktionary dates the word to the mid 16th century and describes it as imitative of the alternate chimes of a bell: the word was made out of the sound, and the two syllables are the two strokes.
維基詞典記的是：這個字大概在十六世紀中期出現，做法是直接模仿鐘一高一低交替敲的聲音。也就是說，兩個音節本來就對應兩下敲擊。後面幾個用法跟這個畫面的連結，是幫助理解的聯想，不等於歷史上一路演變的證據。
Wiktionary, "ding-dong"
登入就可以看每一支怎麼連回核心畫面。