I'm reading this American novel, set in a dystopian future after a global economic crisis. The two main characters encounter a military Hummer vehicle. The vehicle passes by and I read this sentence that I don't understand:

Finally, the truck passes by. There’s the whir of the engine accelerating and the telltale diminished pitch as the airport access road takes it away, west. Everyone, even the army, is escaping.

I don't understand what the word "telltale" indicates in this context. It's a term with many meanings, and I guess the one that fits this context is "an indicator of something," but does it have a more specific meaning? And what exactly does the word "pitch" mean in this sentence?

  • 3
    I think it's a reference to the Doppler effect whereby the sound made by an approaching vehicle appears to drop in pitch (become lower) after the vehicle has passed and is moving away. The phenomenon is telltale because it indicates that the vehicle is leaving. Commented Mar 20, 2022 at 10:15
  • Do enough people know about the Doppler effect to make it a widely recognised 'tell-tale'? Commented Mar 20, 2022 at 12:49
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    As Leachoid says, the phenomenon is familiar to anyone who has heard an ambulance drive past, even if they don't know what it is called. Commented Mar 20, 2022 at 15:00

2 Answers 2


A 'telltale' is literally someone who reveals something about another person that they would rather have not had revealed. The word is used as an adjective to describe something that similarly reveals something. In the context of your example, it seems that the first person is interpreting the sounds of vehicles they can hear but not see, and the details are telling them something important.

You've probably noticed that, when a vehicle is driving away from you, the sound of the engine decreases in pitch, or tone. The sirens of emergency vehicles do the same. Hearing that change in pitch would reveal to you that the vehicle was travelling away from you, and that is what the text is saying - the drop in pitch is telltale as it reveals that the vehicles are leaving.

  • 1
    Don't Americans often call someone who reveals (etc) a 'tattle-tale'? As kids we had a rhyme: 'Tell-tale tit! your tongue shall be slit, and all the dogs in the town shall have a little bit'. Commented Mar 20, 2022 at 12:48
  • @MichaelHarvey That's right, and like many rhymes it had a gruesome background. There were once horrific punishments for the 'crime' of gossip, including being forced to wear a 'scold's bridle' which could pierce or split the tongue.
    – Astralbee
    Commented Mar 21, 2022 at 11:47

Your interpretation of the word "telltale" is correct.

See also this definition from the Cambridge dictionary referring to "important information".

The word "pitch" is used in the sense of the frequency of sound. It is referring to the Doppler effect. You'll be familiar with this effect if an emergency vehicle has ever driven past you with its siren sounding. As the vehicle passes by, the siren sounds changes (the pitch lowers).

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