[Source:] Assistant Professor of Linguistics Andrew McKenzie, University of Kansas

In particular, there is no real reason why certain changes happen while others don't. For instance, the * p sound from Proto-Indo-European became an * f sound in Proto-Germanic. Eventually, this explains why Germanic words like English father, fish, and foot correspond to Latin or Romance words like pater, pisc-, and ped-. We know that in many languages, /p/ changes to /f/ because it's easier to pronounce. But we can't explain why /p/ changed to /f/ in Proto-Germanic and no other branch of Indo-European. There is no why.

1. The title of my question concerns the sentence coloured in grey above. I already listened to audio clips of these IPA symbols here.

2. Which subfield of linguistics comprises questions like this? What are some good introductory books, written for the layperson? I'm guessing historical linguistics and phonology?

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    In addition to @prash 's comment, many Armenians consider ֆ [f] is ruining the phonetic harmony of their language. ֆ is a Medieval adoption to the alphabet (originally dated 405 AD), primarily used for loanwords. Jul 22, 2015 at 7:46
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    I agree with @user6726 below that ease of pronunciation is not relevant for historical sound change, but note that, if infant language acquisition is any indication, an argument could be made that the reverse is true--that is, [p] is easier to pronounce than [f]. Labial stops (oral and nasal) are among the first sounds to be acquired, with the voiceless labiodental fricative [f] coming later on. Jul 22, 2015 at 13:29
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    I wonder if this McKenzie is mistakenly thinking of 'lenition' as being equivalent to 'ease of pronunciation'? Jul 23, 2015 at 0:05
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    My 4 year old kid pronounces "p" from almost day 0, but still can't get "f" right. If "f" was easier than "p", we'd have "fafa" across languages for "dad" instead of "papa".
    – carsten
    Jul 25, 2015 at 20:38
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    Conversely, Finnish doesn't have an [f] except for loan words. Oct 12, 2015 at 15:04

1 Answer 1


It is simply false that "ease of pronunciation" is the reason behind sound changes, although this is a common misconception. In fact, nobody has ever devised a method of objectively quantifying the notion of articulatory difficulty. It is more likely that the change is a result of a chain of perceptual issues, reducing to the problem of distinguishing aspirated labial stops and fricatives.

A three-way study of this topic is necessary, involving phonology, phonetics, and historical linguistics. Historical linguistics can frame the initial question, based on remote relations like Indo-European * p to Germanic * f. Phonetic studies provide the concrete psychological and acoustic basis for speculating about why aspirated /tʰ/ might sound like [ts], and phonology provides the logical glue in terms of the discrete unit sounds of languages where one category changes to another category.

While we lack the factual information needed to explain why Grimm's Law affected Germanic and not Italic or Slavic, we can explain why GL could have happened in the history of Germanic (and other languages which acted likewise). However: this is not a layman's research topic, it requires a relatively advanced understanding of all three areas.

  • The "3-way study" you refer to above comes together nicely in work by Juliette Blevins, Andrew Garrett, and Pam (Patrice) Beddor, picking up the thread of research started by the incomparable John Ohala. Blevins wrote a fantastic book, Evolutionary Phonology outlining a theory of phonetic/phonological change. A thorough synposis is available here: washo.uchicago.edu/seminar/Blevins2006_TL.pdf Also, Mark Hale's book Historical Linguistics: Theory and Method goes into some detail about how a mechanism like this could work. (Disclaimer: Mark was one of my MA advisors)
    – Fred
    Jul 29, 2015 at 0:51

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