Rich Phonology:
Some Background Material
Robert F. Port
Indiana University

Here are some of the critical readings, for your convenience, that support the story told in my papers above.  Linguistic theory assumes that the lowest level of linguistic description is a symbolic phonetic level -- a code for words using a very small number of degrees of freedom, at most about 40 binary phonetic features per C or V segment.   But there is evidence from just about every direction that linguistic memory is much richer and more detailed than that.  We should think in terms of a bitrate several orders of magnitude larger than Chomsky and Halle or Roman Jakobson used. 

Some Introductory Comments       Frequently Asked Questions.

1.  Formal linguistics assumes a low-dimensional fixed phonetic segment inventory.

Chomsky, N., & Halle, M. (1968). The Sound Pattern of English.New York: Harper and Row.  Chapter 1 (3-14) and the beginning of Chapter 7 (pp. 293-309).   Morris HalleNoam Chomsky

This section of SPE lays out the Chomsky-Halle view of universal discrete phonetics.  This idealized version of phonetics has provided the standard phonetic model for several generations of American linguists. There are no competing phonetic models (for American linguists) and there have been almost no changes in this inventory since 1968.  It seems to me the phonology of American linguistics has been mostly isolated from the study of phonetics all this time.   Of course, a few notable phonologists have paid attention to phonetics research, but proportionately very few.

Halle, Morris (1954)   The strategy of phonemics.  Word 10, 197-209. 

This is an early paper by Halle of some historical interest, in which some strikingly hopeful views about phonetics are  voiced.    He points out most people assume ``we speak in a manner quite similar to the way in which we write'' -- that ``speech consists of sequences of discrete sounds which are tokens of a small number of basic types'' -- direct auditory analogs of graphical letters.   However, acoustic analysis of speech sound has shown, he says, that speech is ``a continuous flow of sounds, an unbroken chain of movements.''  He hypothesizes (as he must) that the ``acoustical wave must contain clues which enable human beings to''  segment speech into into discrete events. (I believed that myself for many years.)  ``If we could state what these clues are, we could presumably build a machine to perform the same operation.''   Exactly.  But unfortunately no such machine has been built in the succeeding half century.  In 1954, it may have seemed a good bet that phoneticians and speech engineers would soon succeed. But in 2006, it is no longer reasonable to assume that a low-D description of the physical form of language that is speaker independent and segmented into Cs and Vs will still be discovered.  We simply must give up the  hope for an apriori phonetic description that is both physical and acoustic, yet also abstract and linguistic.

Haugeland, John (1985) Artificial Intelligence: The Very Idea. (Cambridge, MA, MITP). Read Chapter 2 ``Automatic formal systems'', pp.  47-86.    Chapter 1 is also recommended. 

Haugeland's goal was to clarify the assumptions of formalist models of cognition.  These basic assumptions are shared across computing, logic, artificial intelligence and formal models of language and cognition. Major proponents of this view include Chomsky, Newell and Simon, Fodor, Pylyshyn, Pinker, etc.  Computers are carefully engineered so that they can be interpreted in terms of discrete states only.  Programmers (unlike computer engineers) do not need to concern themselves with continuous time or continuous values of voltage. Formal linguistics always assumes an apriori set of letter-like phonetic tokens. Thus it must presume the physical existence of a fixed alphabet of phonetic symbols for spelling linguistic items, as well as a discrete computational apparatus for token manipulation.  All formal linguistic theories build upon this assumption even though it is surely very implausible and the empirical claim of a universal phonetic alphabet has scarcely even been defended by phonologists. (I am sure there must have been attempts, but I'm not familiar with them.)  Chomsky and Halle (1968) took it to be intuitively obvious that such a fixed and small inventory (under a few hundred) of universal phonetic tokens exist.  So the problem, I claim, is that no such low-dimensional description of phonetics is possible (See Port and Leary, 2005).  Therefore formal linguistics is impossible.

2.  Segments are not compatible with spectrographic representations.

IPA, 1999.   Handbook of the International Phonetic Association. Introduction.  (pp 3-13, 27-30, 32-38). 

This thoughtful and wide-ranging chapter of the recent edition of the IPA Handbook (by Prof. John Wells of University College, London) presents explicitly the segmental assumptions of phonetic transcription and does not shrink from reviewing the many problems posed by attempting to represent speech with such letter-sized units.  The trouble is that after reading and considering all the problems, it becomes difficult to believe in the adequacy of transcription as a psychological model -- unless one is biased to believe in the reality of segments (as I was and as the reader probably is).    What I would say is that once you are alphabet literate, phonetic transcription is an invaluable tool for communication about language and speech. I will continue to use it freely myself.  It is not, however, an adequate psychological model of linguistic representations for any speaker -- whether alphabet-literate or not.

Klatt, Dennis (1979)  Speech perception: A model of acoustic phonetic analysis and lexical accessJournal of Phonetics 7, 279-342.

 Klatt presents two generic models for recognizing speech in this important paper: LAFS and Scriber.  LAFS (``lexical access from spectra'') recognizes words specified in raw acoustic form.  No segment level at all!  Given all the variations due to context, speaker, etc, this implies there will be many alternative acoustic representations for each speech chunk (whether word, phrase or what).  Today, all effective speech recognition systems work basically this way, usually implemented as hidden Markov models on sequences of spectral shapes (specified in a rather large `alphabet' of spectral shapes).  But Scriber works the ``right'' way (according to the insights of linguistics) since it converts spectra into abstract segmental, letter-like units, and then recognizes words and other speech chunks using the resulting transcriptions.  Back in the 1980s, my Indiana colleague David Pisoni always liked this paper and thought that LAFS was a model that deserved serious consideration. But I, as a linguist-phonetician, thought that LAFS could not possibly be correct.  I remember being almost annoyed that Dennis Klatt even suggested such a thing. ``Oh well,'' I thought, ``he is just an engineer. Psychological plausibility is not so important for engineers.''   This paper appeared in 1979, only 3 years after I got my PhD, and now, 30 years later, I realize that the general approach of LAFS was the right choice all along!  And is, in fact, the only psychologically plausible approach. The Scriber approach, despite its great intuitive appeal to any alphabet-literate person, is not guaranteed to work.

Huckvale, Mark (1997)  10 things engineers have discovered about speech recognition.  NATO ASI Workshop on Speech Pattern Processing. pp. 1-5.

This paper has many surprises for linguists.  ``This paper is about what happens when you put Performance first'' -- relative to Competence.  Huckvale has many humbling things to say to linguists.

Ladefoged, Peter (2004)  Phonetics and phonology in the last 50 years.  Paper presented at `From Sound to Sense', a conference at MIT.

This interesting paper on the history of phonetics presents his concerns about the gross mismatch between segmental linguistic descriptions of speech and the acoustic signal.  He concludes rather disturbingly: ``phonologists have the problem of deciding whether they are describing something that actually exists, or whether they are dealing with epiphenomena, constructs that are just the result of making a description.''  My conclusion, of course, is the latter, and I think Ladefoged's was as well.

Ladefoged, Peter (2005) Features and parameters for different purposes. Paper presented to the Linguistic Society of America, 2005.

This paper presents Ladefoged's final views on phonetics and phonology before his passing in January, 2006.  Using generally different arguments than mine, he concludes that a full description of speech requires far more degrees of freedom than Chomsky and Halle propose and that a grammar could not possibly be ``just something in some speaker's mind.''    Instead he proposes that the phonology of a language is ``a social institution,'' while ``the acts of speaking and listening all involve adjusting articulatory parameters not phonological features.''  On the other hand, he says, ``phonological features are best regarded as artifacts that linguists have devised in order to describe linguistic systems.''   Although he does not develop these ideas much beyond these statements, this appears to be essentially identical to my position: phonology is a social institution existing on a slow time scale and real-time language processing makes no use of abstract phonological descriptions at all.

3.  Variation is endless when you look close.

Labov, William (1963) The social motivation of a sound change. Word 19, 273-309.    Reprinted in W. Labov (ed.) (1972) Sociolinguistic Patterns. (Univ. Penn Press).

Labov, William. (1964) Phonological correlates of social stratification. American Anthropologist 66, 164-176.

The first paper is Labov's fascinating MA thesis and the second reviews the results of his dissertation on language variation on the Lower East Side of NYC.  Labov revealed vividly the subtlety in dialect variation.  Of course, each individual speaks a different dialect, but in fact, we each speak in many different styles of pronunciation detail.  Our theories of language presume there is a linguistic state, something we could call `The English Language' or maybe `Lower East Side English' -- in any case, some invariant Grammar.   But Labov's data show us (in my view, not necessarily his) that no such entities are definable in fact.  Everything is always subject to subtle phonetic variation.   All we can know about a language is distributional patterns in a high-D auditory/phonetic space. Traditional theories of language presume that speaker and hearer share some common Grammar. But the fact is they never ever share the same grammar!   And every word has an unlimited number of variants!    So why do linguists imagine they could describe some dialect or other in discrete low-D terms?  

 Bybee, Joan (2002)   Word frequency and context of use in the lexical diffusion of phonetically conditioned sound change.  Language Variation and Change 14, 261-290.

   Bybee and other variationists have explored the ways that the distribution of variants for any word is influenced by such properties as the frequency of occurrence of each individual word -- as well as many other factors.  If every word has a bazillion variants, what can it mean to say ``I know Word X''?  Apparently it must mean either (A) ``I know the list of (essentially) all variants'' or, perhaps, (B) ``I am able to evaluate utterances for their similarity to the whole distribution of variants of Word X.''  This does not resemble what generative phonologists are doing -- but they too think they are explicating what it means to know Word X. 

Johnson, Keith (2004) Massive reduction in conversational American English. In K. Yoneyama & K. Maekawa (eds.) Spontaneous Speech: Data and Analysis. Proceedings of the 1st Session of the 10th International Symposium. Tokyo, Japan: The National International Institute for Japanese Language. pp. 29-54.

Johnson studies a corpus of conversational speech and documents the huge variety of pronunciations for individual words.  He compares each word with its `canonical' dictionary pronunciation and shows that over 60 % of the words in the corpus have at least one phone that deviates from its canonical form and and 20% of the words have at least one phone deleted altogether.   Of words of 4-6 syllables, 22% of them are missing at least 2 entire syllables!  He argues that this demonstrates the falsity of two central assumptions of traditional phonology: the Segmental Assumption (that words are spelled from units that are analogous to alphabetic letters) and the Single-Entry Assumption (that each word has a single, prototypical representation).

4.  Long-term memory, including memory for words, is far richer than we thought.

Palmeri, T. J., Goldinger, S. D., & Pisoni, D. B. (1993). Episodic encoding of voice attributes and recognition memory for spoken words. Journal of Experimental Psychology, Learning, Memory and Cognition, 19, 309-328.

This paper presents powerful evidence from a `recognition memory' task that our memory for speech is not abstracted away from speakers' voices, as linguists and phoneticians tend to think (as claimed explicitly by Morris Halle, 1954 and 1985).  We actually store lots of phonetic detail including speaker idiosyncrasies.  This set of results troubled me for over a decade until I finally decided that I should try to consider that the data might actually mean what they seem to mean -- that an abstract phonological transcription of speech
does not do the primary job of linguistic memory and does not limit what is stored in memory.  This mental exercise is what led to the revolutionary theory being presented here.   One implication  of these results is that we store far more detailed information about speech than we linguists ever imagined.  It also implies we store speech in a very concrete, auditory fashion -- not using abstract speaker-independent and context-free descriptors.  Thus,  a memory including specific examples (as well as prototypes and abstract specifications) is implicated.  It turns out that lots of data from many areas of psychology have been implicating such representations for a long time.

Hintzman, Douglas (1986)  ``Schema abstraction'' in a multiple-trace memory model. Psychological Review 93, 411-428.    The image “” cannot be displayed, because it contains errors.

This, the granddaddy of mathematical memory models, is called Minerva2, and is easier to understand than most since the math is simple linear algebra.   You will see how a rich and detailed memory of concrete exemplars with no abstractions can perform better on training tokens yet still allow abstractions (and prototypes) to be computed on the fly whenever needed.  Many more recent models (e.g., by Nosofsky and Shiffrin) use different mathematics but retain a key role for the training exemplars to predict results. (The pic: Doug Hintzman.)

O'Reilly, Randall and Kenneth Norman (2005)  Hippocampal and neocortical contributions to memory: Advances in the complementary learning systems framework.  Trends in Cognitive Sciences 6, 505-510.  

This proposes a neural model for `episodic memory,' that is, memory of randomly coocurring events (eg, the words  you hear someone say to you, or the specific events that happened on the way to work this morning) that represents stored information on a single trial.

Gluck, M., M. Meeter and C.E. Meyers  (2003) Computational models of the hippocampal region: linking incremental learning and episodic memory.  Trends in Cognitive Science 7,  269-276.

The point of these papers is that there are neurologically plausible mechanisms that can learn details of specific examples of complex, multimodal episodes on a single trial without repetitive training.  These papers suggest that a surprising amount of rote material could be available in the memory of speaker-hearers.  Remembering all examples forever is not plausible, but we apparently remember much richer detail -- including language detail -- than most of us imagined.

              Any implications for the study of language?  Of course.

Pisoni, D. B. (1997). Some thoughts on `normalization' in speech perception. In K. Johnson & J. Mullennix (Eds.), Talker variability in speech processing (pp. 9-32). San Diego: Academic Press.   

David PisoniLachs, Lorin, Kipp McMichael and D. B. Pisoni (2000) Speech perception and implicit memory: Evidence for detailed episodic encoding of phonetic events.     In J. Bowers and C. Marsolek (eds.) Rethinking Implicit Memory (Oxford: Oxford Univ Press).
Also in Research on Spoken Language Processing, 24, 149-167 (Psychology Dept, Indiana University).

 Pisoni and colleagues draw the implications for a theory of language of the fact that people use an episode-like memory rather than an `abstractionist' model of speech (like phones or phonemes).  Lachs et al. point out that the traditional perspective on speech perception assumes that linguistic information and contextual information are stored independently.  Instead they argue their data support a ``single complex memory system that retains highly detailed, instance-specific information in a perceptual record containing all of our experiences -- speech and otherwise.''    They are calling for a new kind of linguistics that lets go of the assumption of discrete abstract units.  Such a theory of language is what I am now trying to initiate with this website.

Pierrehumbert, Janet (2001) Exemplar dynamics: Word frequency, lenition and contrast.  In J. Bybee and P. Hopper (eds) Frequency Effects and the Emergence of Linguistic Structure.  (Benjamins, Amsterdam), 137-157.
    She explains exemplar models (based on Hintzman) in her own way and addresses the question of how an exemplar model of memory might make predictions about speech production.  She proposes that the perceived (and stored) distribution can be a direct model of production probabilities.  So her algorithm for choice in speech production is simply the distribution of perceived tokens treated as a probability distribution of production targets selected from randomly.  This is one of  the first attempts by a linguist to consider the implications of detailed exemplar memory representations of speech.

Johnson, Keith (2005, mspt)  Decisions and mechanisms in exemplar-based phonology.  UC Berkeley Phonology Lab Annual Report 2005.   Johnson considers some  issues that will trouble linguists about exemplar models of memory for language.

These studies illustrate attempts by speech psychologists and linguists to address the issues raised by episodic or exemplar memory in the context of language.  All of these lean on Minerva2 (Hintzman, 1986) as the paradigm model to develop predictions from.  Perhaps readers might want to consider developing their own predictions from Minerva-2 for application to some area of particular interest to them -- whether language acquisition, reading skill acquisition, language change, sociolinguistics, syntax, etc. 

5.  What modality are phonetic targets?:  articulatory, auditory, somatosensory?

 Liberman, Alvin M., Franklin S. Cooper, Donald P. Shankweiler and Michael Studdert-Kennedy (1968)  Perception of di du spectrograms speech code.  Psychological Review 74, 431-461.    Reproduced in J. Miller, R. Kent and B. Atal (eds.) (1991) Papers in Speech Communication: Speech Perception.  (Acoustical Society of America, Woodbury, New York).

A monumental review paper summarizing the Haskins Labs view of speech perception arguing for the `motor theory of speech perception'.   This group thought that words must be specified in memory in low-dimensional, segmental and articulatory terms, so the  di/du problem (illustrated at right) was major.   But if auditory memory is very large, then speakers can just store context-sensitive formant trajectories and burst spectrum shapes.  The fact that  di and du begin with what we call ``the same sound'' may be something that is noticed by most speakers only after learning to write with an alphabet.   At least this issue about what speech sounds ``sound the same'' needs more research.

   Lindblom, Björn (2004) The organization of speech movements: Specification of units and modes of control.  Paper presented at conference `From Sound to Sense' at MIT.  A survey of speech production theories. 

 Diehl, Randy, Andrew Lotto and Lori Holt (2004) Speech perception.  Annual Review of Psychology 55, 149-179.   Presents that case that, no matter what, the basic representations of word targets must be auditory.

Gallantucci, Fowler and Turvey   (2006)  The motor theory of speech perception reviewed Psychonomic Bulletin and Review 13, 361-377.

Guenther, Frank (1995) Speech sound acquisition, coarticulation and rate effects in a neural network model of speech perception. Psych Review 102, 594-621. 

Guenther, Frank and Joseph Perkell (2004) A neural model of speech production and supporting experiments. Paper presented at `From Sound to Sense', conference at MIT, June 2004. Available at  

Speech sounds must have both convenient articulatory properties and practical auditory properties. Diehl, Lotto and Holt argue for a speech perception process using only general auditory capabilities (rather than unique specialized perceptual skills that are used for speech and nothing else).   Clearly, my position is closer to theirs than to the traditional Haskins Labs view.   Guenther's feedforward production system just produces gestures -- normally with no feedback.  But the primary realtime guidance for them is based on somatosensory (ie, orosensory) feedback (from muscles, joints and skin surfaces).   So the best answer to a question about realtime targets is: the targets are somatosensory, and neither gestural nor auditory.   So I don't agree (with Galantucci-Fowler-Turvey) that  ``perceiving speech is perceiving gestures'' (their claim number 2), it is just perceiving speech.  But their claim 3 that ``the motor system is recruited for perceiving speech'' seems to be true and provides a coherent, reliable coding method for storing speech patterns.  (See Stephen M. Wilson, 2004, Listening to speech activates motor areas involved in speech production. Nature Neurosci.)

6.  Short-term memory uses an articulatory code.

 Baddeley, Alan D.  (1992) Working memory. Science 255,   556-559.

Wilson, M. (2001). The case for sensorimotor coding in working memory. Psychonomic Bulletin and Review, 8, 44-57.

The issue regarding short-term memory (STM) is how words are stored for short periods of time -- under 20 sec or so.  Baddeley uses the term `phonological loop' for the system that stores a small number of words for a few seconds.  Linguists might assume that he means the same thing they mean when using the term ``phonological''.  But his data show that this code is either an auditory code or an articulatory one -- but it is definitely not the kind of abstract, segmented, speaker-invariant code that linguists think of when they use this term.  So the code is either motor or auditory (or both).  Note that Baddeley claims the phonological loop has two parts -- a store or buffer (which exhibits confusion between words that sound similar even if articulated quite differently) and a (subvocal) motor representation used for rehearsal (which accounts for why Ss can remember fewer longer words than shorter ones, ie, the `word-length effect.'

Baddeley, Alan, D. (2002) Is working memory still working?  European Psychologists 7, 85-97

In this paper Baddeley extends his earlier model in a useful way by added an `episodic buffer' --  a store for information from many modalities that is retained for awhile.

7.  Why are letters so convincing despite all the evidence?  Because of our education.

Olson, David R. (1993)  How writing represents speech.  Language and Communication 13. 1-17.   This article is  a revised version of Chapter 4 in his outstanding and highly recommended book: The World on Paper: The Conceptual and Cognitive Implications of Writing and Reading. (Cambridge:  1994).   He points out that various human notions of what language is are invariably based on whatever we represent with our writing system.  So the idea that our alphabetical writing is a `cipher' (one-to-one replacement) from phonemes into graphemes has reversed the true order!  We linguists tend to believe our language is made from phonemes primarily because we use letters to represent speech.

Greek schoolboy  Faber, Alice  (1993)  Phonemic segmentation as epiphenomenon: Evidence from the history of alphabetic writing.  In Downing, Lima and Noonan (eds) The Linguistics of  Literacy.  (Benjamins, Amsterdam) pp. 111-134.  

Faber anticipated the argument I am making here over a decade ago.  Her paper has been largely ignored, as far as I can tell.   She argued that languages seem to be composed from letter-like segments primarily because we have all been trained in alphabetic literacy.

Abercrombie, David (1949)   What is a `letter'?   Lingua 2 , reprinted in D. Abercrombie  (1965) Studies in Phonetics andalphabet blocks Linguistics. (Oxford Univ Press, Oxford), pp. 76-85    A quick, historical look at confusion from the Greeks to modern times about whether letters (Lat. litera) are graphic tokens or `speech sounds.'   Abercrombie thought the story was very clear in 1949 -- since, of course, he assumed that phonemes were the correct cognitive units. But  it seems to me that he was still very confused himself about these issues.  Neither he nor most other phoneticians were ever able to sort out the source of our vivid intuitions about the segmental structure of speech.

8.  Almost noone perceives phonemes until given literacy training.

Morais, Jose, Luz Cary, Jesus Alegria and Paul Bertelson (1979)  Does awareness of speech as a sequence of phones arise spontaneously?  Cognition 7, 323-331. 

Read, Charles Yun-fei Zhang, Hong-yin Niew and Bao-qing Ding (1986) The ability to manipulate speech sounds depends on knowing alphabetic writing.  Cognition 24, 31-44. 

 Carroll, Julia (2004)  Letter knowledge precipitates phoneme segmentation, but not phoneme invariance.  Journal of Research on Reading 27, 212-225.

These papers show quite clearly that a segmental description of speech (in terms, that is, of consonants and vowels) may be intuitively persuasive for us. But it is not universal -- indeed most humans, through our history, have not had such intuitions. It appears that some amount of alphabet training is necessary for people to hear speech in terms of Cs and Vs.   

          Ziegler, Johannes and Usha Goswami (2005) Reading acquisition, developmental dyslexia and skilled reading across languages: A psycholinguistic grain size theory.  Psych Bulletin 131, 3-39. 6year olds reading

This review paper strongly endorses the view that the alphabetical description of language (using phonemes or letters) is a result of learning how to do alphabetical reading and writing. It also demonstrates that the inconsistencies in the spelling of English greatly complicate the problem of learning to read.   Children taught to read Finnish or Italian can read new words as well after one year of school as English-speaking children can do after 3 years of school.  Of course, the latter's practical reading skill may still be better than a child learning to read Chinese after the same amount of training.

  Rayner, Keith, B. R. Foorman, C. A. Perfetti, D. Pesetsky, M. S. Seidenberg (2001) How psychological science informs the teaching of reading.  Psych'l Science in the Public Interest 2, 31-74.   

Studies of reading reveal clearly how an understanding of language in terms of phonemes is almost entirely a consequence of learning how to read with an alphabet.  This direction of causality agrees with my general story that segmental descriptions of speech are shaped and reinforced by extensive practice at reading and writing.  But this result is in serious conflict with the conventional views of linguists and psychologists about language.  The traditional view insists that learning a language and remembering vocabulary are skills that depend upon letter-like phonemes. Some set of letter-like units are said to be available in advance to all members of the species.  On this view, all speakers, whether literate or not, should store language using a cognitive alphabet.  But the data do not support any such predictions.

Of course, there is the question of how the alphabet could have been invented if phonemes lack this intuitive basis.  But it should be kept in mind that the early Greek alphabet was the result of roughly 3000 years of efforts in the middle east to engineer a culturally transmittable writing system that was easy to teach and use.   And the alphabet was only invented once -- as has been pointed out many times.  I would claim that those Greek `writing engineers' (standing on the shoulders of earlier middle-eastern writing engineers) actually invented the phoneme concept itself.  The phoneme is the ideal, the conceptual archetype, for which all alphabetical orthographies are just imperfect implementations.

Ghosts in our Machine So what ARE speech `segments'?   Phones and phonemes are the phantoms of letters.   After we have learned to read letter strings as words, and to write words as letter strings, a letter-based description of speech seems completely natural and appropriate.   Everyone reading this page has spent from 15 to 50+ years developing skills at reading and writing language using one or more orthographies and perhaps using a phonetic alphabet like the IPA.  A letter-based representation has become our most natural way to interpret the complex, overlapping and mostly unobservable gestures of speech.  But those discrete sound units that we think are the only possible representation of speech are really just the cognitive images of the letters we would use to write speech down. That is, letters provide a model for our understanding of speech.  Phones and phonemes are idealized versions of the letters we write with.   There simply are no such things as ``speech sounds.'' There are no countable sound-objects.   In fact, there are only continuous streams of ``the sound of speech'' and overlapping, sometimes rhythmically constrained speech gestures.  Our perceptual and memory systems deal with this reality. But in our conscious experience there also live the ghosts of letters.  They are largely useless for perceptual, motor and memory purposes. But they are properties of speech that are very useful if you happen to have something like a paper and pencil and a few years of daily training.  The discreteness and serial ordering that we hear so vividly in our conscious experience of speech are properties that actually pertain only to letters, not to sound.

To Frequently Asked Questions

ancient Egyptian school

Robert F. Port, April 9, 2008