Intelligibility of children's speech

[Margaret Fleck]

Before making *any* claims about child speech here, I would very stronglyrecommend also tracking down numbers for the obvious control:  adultconversational speech.    It's well known in the speech community that bitsof adult speech are frequently unintelligible, or unintelligible without contextof varying amounts.   Or they seem intelligible until you try to transcribe themand try to pin down exactly which words were said.   I've seen the same typeof demo done with adult speech.
I don't have a percentage handy.  But I'm in the middle of a project syncing the twotranscriptions of the big Switchboard corpus and probably something like 10% of theutterances have a significant difference between the two transcriptions.     In my case, significant means a difference likely to change the syntactic parse, not just (say)replacing "me" with "you".  If you ask me in a few months, I might have a real number.
For adult speech, the rate depends massively on your standard for "intelligible",the type of speech, and the type of utterance.    Important content words from recent radionews recordings probably have near 100% intelligibility.    Filler words ("you know whatI mean") in conversational speech are frequently mashed into formless blobs ofaudio.    Parochial words (e.g. Kalman filter, slub, gorp, rennet, all proper names) are likely to be mistranscribed if the transcriber doesn't have the right backgroundknowledge, even with the context of the rest of the conversation.
It's also essential to match the dialects.   Not only are some pairs of (decently-sized)English dialects not mutually intelligible (e.g. Johannesburg and Newark New Jersey, as my husband discovered) but smaller mismatches create errors.    Recall that boththe quality and number of distinct vowels vary dramatically across the northeasternUS.   This immediately creates a big population of content words that are ok in context but unintelligible in isolation.   Worse, the vowels are moving, so that an adult from"the same" dialect doesn't pronounce them the same.  Bill Labov is famous for demos on these points.
Moreover, familiar words are compressed relative to less familiar ones.    That's abig effect which has to be controlled for.    It is unknown how much this effect ispurely created by the speaker's convenience and how much is their perception ofthe hearer's requirements.    Little kids have their own theories of the hearer's needs.If their household eats Weetbix or dal, they may think it's familiar to the gradstudent interviewing them where an adult might guess it's unfamiliar and articulatethe word more carefully.
Finally, it may be important to control for utterance length.   Adult speech offerslong utterances that provide internal redundancy.   The very fact that the childrenhave shorter utterances will immediately reduce intelligibility for the utterance inisolation.   Brief answers to questions (e.g. "some cruellers") that were originally saidin a strong context might provide a good parallel to the situation with children.   (Forthose of you not from New England, where it's a common word, those are twist donuts.)
Margaret Fleck (U. Illinois)
--- On Thu, 2/4/10, Nick Riches <nick.riches at googlemail.com> wrote:

From: Nick Riches <nick.riches at googlemail.com>
Subject: Re: Intelligibility of children's speech
To: "Info-CHILDES" <info-childes at googlegroups.com>
Date: Thursday, February 4, 2010, 5:04 AM

Dear Mats

I attended a very interesting talk by Sara Howard, a clinical
phonetician at Sheffield university, in which she gave a demonstration
of a single child's utterance which was completely unintelligible
without a context, but completely intelligible with the context. In
fact it made the audience gasp! She might be a good person to
approach.

Nick Riches

University of Reading

On Feb 3, 8:41 pm, Mats Andrén <mats.and... at ling.lu.se> wrote:
> Dear list members,
>
> A few years ago I read an article or a book where it was stated that X
> percent (a large number) of children's utterances became more or less
> completely unitelligible when the video is taken away. That is, removing
> the visible context and action/gesture et cetera and relying only on the
> audio signal as a source of interpretation. I can't recall who wrote it
> (it *could* have been Eve Clark or Jana Iverson). Neither am I able to
> remember whether it was a result of an experimental study of some kind,
> or some more sweeping approximation. I also do not remember the age of
> the children involved, but it should have been some time during their
> second year of life (maybe earlier). Precisely due to all this
> uncertainity, I would be most grateful if any of you would be able to
> point me to information about these matters. Any publication that deals
> with this question is of interest.
>
> Have a nice day!
>
> Best regards,
> Mats Andr n,
> PhD student in General Linguistics,
> Centre for Languages and Literature/Centre for Cognitive Semiotics,
> Lund University,
> Sweden

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