~d of Computational Linguistics 
A CASE HISTORY 
GDMPUTER EXPLORATION 
FAST SPEECH RULES 
Douglas B. Moran 
"S;. of Computer & Communication Sciences 
University of Michigan 
Ann Arbor, Mlchigan 
Copyright 1975 
~dation for Computational  in-guistids 
Abstract 
-- 
In conversational speech, words run toq6t her and interact 
causing thei phonological f~rms to differ from their citation 
forms. Fast speech rules attempt t3 qescribe these changes as 
speech becomes faster and more casual, 
In developing 3 ny set of phonological rules, computerized 
grammar testers are a useful and important aid. They necessitate 
(3. precise, aonsistent Eornulation of the rules and allow the 
generation of s-ple d.erivations. In applying these ~ules to a 
diverse set of utterances, we can first confirm that the rules 
really dc apply where we expect them to, and then experiment vith 
various rule orderings to obser~e their effects. 
The Phonological Grammar Tester of Friedman and Morin was 
use-d to test two sets Of* fast spe'ech rules from the ARQA Spsech 
Understanding Research ccmmunity. Working with C hese rules lad 
to certain observations about the interactions and nature of fast 
speech rules in general. 3x1 addition to testing these two sets 
of fast speech rules, we were also interested in the problems of 
teSting such a grammar vith this program. 
Appehdices incltlde an overview of the grammar tester and 
finaJ output from our testing, 
Table of Contents 
--------------.lC 
..................... Testing the Fast Speech Rules .......... 5 
.......................... 
Sutgqested Wodif ieations to t'he PGT 10 
Observations about Fast Speech Rules ........................ 12 
References .................................................. 15 
Appendix A . Using the Phonological 
Grammar Tester ..................m.....m...... 18 
. Appendix B Sample Output .m.................................. 21 
. Appendix C First Set of Rules ............................. 24 
.................. 
Appendix D - Final Rules with Edited Output 30 
4 
fi Case History in Computer Exploration of Fast Speech Rules 
Couglas B. Moran 
The University of Michigan 
Introduction 
---I----*- 
In developing any sebt of phonological rules, computerized 
grammar testers are a useful and important aid. They necessitate 
a precise, consistent formulation of the rules and aL1ow the 
generaticn of sample derivations. In applying th~se rules to a 
diverse set of utterances, we can first confirm that the rules 
really do 3pply where ue expect them to, and then experiment with 
various rule orderings to observe their effects, 
Tradit iona 1 phonological rules describe transitions from the 
underlying form to the surface form of a word. However, in 
casual (fast) speech, words are not distinct, independent units, 
but run together and interact. Fast speech rules atte~pt *-o 
describe these changes that occur as speech becomes faster and 
more casual (4, 8, 9). 
This is a. case #history of the examination of two particular 
sets of rules on the Phonological Grammar Tester (PGT) of 
Friedman and Borin (3) . An overview is given in Appendix A and a 
sam~le of the output in Appendix 8. In addition to testing these 
two sets of fast speech rules, we were also interested in the 
problems af testing such a grammar with this program. 
Testing the Fast Seeech Rules 
-- --I- ---CmIIILI.I. 
For our f j cst test, w chose the fast speech rules of Neu 
(6) as the best available set of rules given in a reasonably. 
consistent notation. The rules Mere given in two formats: one 
usidg phonemes and the other using distinctive features. The 
first task was to adjust the notation into a machine usable form. 
For the purposes of this test, we used the feature systeh of 
Chomsky and Halle ('I), with three types of boundaries: syllable 
(+ , morpheme (3) and word (#I) . For example, the f eatur'es 
anterior 
-----a and ------ coronal had to be substituted for &ace' _of 
art i~u1ati.o~. Also, the rules had to be modified so that each 
featur-e had the same type of value (integer, binary, gr marked- 
unmarked) th~ongbout the grammar. For example, in the PG?, 
lstress is not equal to +ssess and is less than =stress, which 
----- f 
could cause manf unexpected problems in the grammar. Another 
minor problem was aetermining whether a C I in the rules meant 
not ----.-- a vo we1 , I+ consl, or up-- vocall. 
Sample derivations were given with the rules, and these. were 
.used as a first test. We quickly found a number of small 
problems, most being that the rule had been incorrectly or 
incompletely stated. For example, Geminate Reduction and 
Alveolar Flapping would not apply across the word boundary in 
"want to", while the E in "captain1v blocked the application of 
 lott tali eat ion. 
More sample words were taken from. Neu and several more small 
erro-1s were faund, such aa Nasal Consonant Deletion bleeding 
Transitional Stop Insertion and thereh y indi'cating that it should 
be ordered after Transtop. We still had SOB-e unresbl ved 
problems, such as "Ts /f e d a 1/ a proper fast speech form of 
'f.ederal'?lg, when the revisions and additions (7) arrived, Many 
of thes e revisions corresponded to our solutions of problems 
encoun\telCed during testf ng of these rules. The f iaal form of 
this first sot is given in lppendix C. 
Since there was little obvious order in the rules, graphing 
the ~artial ordering given was very helpful in exploring the rule 
ordering. The partial ordering given with the rulas, Ficrure 1, 
was quickly refined to that in Figure 2 by testing the sample 
der i va't i cns . 
In these new 'rules, particular attention was paid to the 
presence and posit ion of syllable, aorphene and word boundaries 
in the environments for which the rules should apply. Other fast 
speech rules from members. of the ARFA Speech Understandipg 
Research (SUR) community (11, 12, 13) vere used 3s references, 
especially in respect tb boundary position, in impledenting fh ase 
new rules. In testing the rules, most of the problems involv'ed 
the positioning and poesence of boundari-es. 
The second Dental Deletion rule was dropped from the grammar 
because it appeared tc duplicate the effect of assimilating an 
alveolar flapped g to the preceding 5. 
We had few transcriptions of fast speech forms, so in 
GRAPH OF PARTIAL ORDERING 
-- 
LINEARIZED 
-....----- 
SCHWA DELETION 
<ING> REDUCTION 
RUH-REDUCTION 
RUH-LESSNESS 
NASALIZED VOWELS 
NASAL CONSONANT 
EEL ET I0 N 
DENTAL DELETION 
ALVEOLAR FLAPPING 
GLOTTAL STOP 
FoRHqTIoN 
PALATALIZATION 
A SSI 31 LA TZO N 
TFiAN SITIONAL STOP 
INS ERTION 
GEKINATE REDUCTION 
DARK [LJ 
[ RJ-FLAPPING 
FIGUR" 1 INITIAL RULE ORDERING 
I--&--&----------------- 
LINEA RI7;ED 
---------- 
VOWEL REDUCTION 
SCHWA OELFTION 
<IkG> REDUCTION 
RUH- REDUCTXON 
NASALIZED VOWYLS 
TRANSITIONAL STOP 
INSERTION 
PALATALIZATIOY 
A LVEOLAP FLAPPX N!: 
GLOTTAL STOP 
FORMATION 
DENTAL DELETION 
GEHX NATE RS'D UCTION 
NASAL CONSONANT 
REGBCT ION 
DARK [L] 
GRtAPH OF P4RTI:AL ORDERING 
--..-.----..------- --------- 
FIGURE 2 PINAL RULE ORD~~~l4 
,,,,,,,-:, 
testing these rules a major problem was in determining wha-t did 
and did not constitute proper fast speech forms. In slow speech, 
it is fairly easy to break up the utterance into a sequence of 
phonemes, but in fast speech, the utterance is more contiquous 
and it is harder to decide what is a segment and wh.ere the 
segments begin and end. For example, the palatalization rules 
produce the following derivation: 
(a) . /did#Cyu/ 
b) . /di## yyu/ 
(c). /dittyu/ 
We are not inclined to believe that an intermediate form 
/did##Yyu/ exists between steps (a) and (b) in this derivation. 
I think that (b) is a true intermediate form, existing in slower, 
casual speech, but not in fast speech. 
Our best evidence indicated that the RUH is the same as the 
syllabic "rU I thus raising the problem of ordering the 
Syllabicizing and Ilu h-rsduct ion rules. Are the proper forms 
/g u v +- n r/ ahd /f e d + r l/ or, more likely, /g u v + n r/ 
0 
and /f e d + r I/? Qc, could it possibly be /g u v + n r/ and 
/f e d + r I./, with the Syllabicizing rule not deleting the 
schua, but naking it very short and passibly devoicing it? 
Another disturbing result of the testing vas the application 
of rules across deleted segments. For exaaple, after qqvernqg 
has been reduced to /g u v + n r/, Proqressive Assimilation 
applies, producing /g u v + m r/. Similarly, ---- sanitq ------- clause 
becomes /s ae n + t a .../ which becomes /s ae n + f' a .../, 
closing in on a .fast speech form of santa Claus. The final form 
of the second set of rules and the output are given in Appendix 
D 6 
Suggested &dific_gtions to the PGT 
- -----.. - ---------I- 
The PGT was writfen for the testing of traditional 
ph~nologicat grammars which take an underlying form to a Burface 
form, and thus fast speech rules present several unforeseen 
problems. 
Fast speech r'ules do not constit.ute a conpleke grammar, but 
are iostead interspersed, among the traditional rules, Ln 
producing an intermediate or surfhce  for^ for input to the 
grammar, the use of diacritics would praduce 2 simpler and more 
econcmical represent a tion st the input For example, in the 
present system, it is necessary to give a separate definition for 
each stress assignment for each vowel, instead of defining each 
towel cnce and assigning the stress through the use of 
diacritics. 
Syllabification aDpears to occur before some of the rules, 
an d after others. TO avoid having to insert, rules for 
syllabificatio~~ or having the rules preceding syllabification 
ignore syllable boundaries in the input, the PGT should have a 
l@human intervention" rule which would allow the user to chmge 
the tree as part of the derivation, simulating the effect of the 
WmissingfI rules. "Human interventionn rules could be used to 
postFone Qriting rules, either ro a later session or indefinitely 
if the rules are too hatd to write or if they are &atsi.de the 
scope of the problem. 
Another problem arises from most, if not all, fast spzech 
rules being optional. The present system generates a single 
derivation using a  ando om number generator to decide whether or 
not- to apply optional rules. As a result, to obtain a good best 
of the effect of an optional rule in tho grammar, we have to do 
two tests, Ohe with the rule obligatory and one without the rule. 
With. a large number of optional rules operating on a rron-trivial 
set of test data, having to test each possible rule combination 
individually would be a- staggering task. A more satisfactory 
method wquld be for the PGT to produce a set of derivations such 
that any tine an optional rule can apply, the PGT produces a 
derivation for the case where the. rule was applied and one for 
the case where it wasn't. Cohen ana Mercer (2) have implemented 
such a feature in their rule tester by storing the result of the 
application of a rule as a directed gra.ph. Subsequent rules are 
applied to all paths through the graph, producing a neu graph. 
In considering the problem of when an optional rule should 
be applied, we are considering pgfouance (10) . To this end, we 
might be better served by having the variable rules of Iabov (5) 
ia addition to traditional phonologica1 rules. f nstead of the 
all- or- nothing matching of normal rulas, variable rules employ 
incremental matchins, with the likelihood of the rule being 
applied being a function of the degree of match, the rate of 
speech, and the nature of the conversation (e,g. Is it formal or 
casual?) . For example, for: the Froqrelssive Assimilation mile for 
point of articuigtion (PROARTICJ , /s O f n/ ((soften) becomes 
/S (3 f m/ only in very fast speech, hut /p r + f y u + n/ 
v N 
(profusion) becomes /p c + f y u + z n/ in sost fast speech. In 
additian, for each variable rule applied, the PGT should use the 
associated probabili tv tc produce a Einal probability for each, 
derivation. Unfortunatelyr the ilbpleaentation of variable rules 
would necessitate major changes to the PGT. 
Convenient, but not necessary, would be the ability to make 
a rule "blindw to certain types of nodes, For example, Chomskp 
and Halle (1) allow sosle boundary symbols to be invisible to 
their phonological rules. Tn some cases, this ability might be 
able to fulfill the function of a "human interventionv rule, 
Observat ions about Fast Skeech R ules 
-------------.---- ------ 
Testing the fast speech rules led ta certain insights into 
the interactions of the rules. The most vexing problems verbe 
with the representation of boundaries. The use of 2, &, and gt 
seems artificial and cumhersome, A moce natural approach seems 
to be to assign the boundaries varying degrees of $treggf_h, and 
then allow the phonolcgical rules to operate on the strength 
assignments. Consider the problem of HJohngs going to uorkll 
becoainu the fast speech form l'Johnts qonna work1' in the case 
where qoinq is an auxiliary but not in the case uhere it is the 
verb. Rather than having the phonological rule sensitive to the 
syntax, -it seems much cleaner to have it sensitive tp the 
boundary strength between on and to. To this end, we must 
allow the syntax to influence the initial assignaents of boundacy 
strength. The use of boundary strengths also seems to solve the 
problem, of how boundaries are reduced. For example, in reducing 
want to to wanna should the word boundary be reduced to a 
me--- ---I 
morpheme or a syllable bounda'ry? 
Another ase of boundary strengths might be to mark the 
position of segments deleted fcom a word by strengthening the 
neighboring boundaty. For example, when governor ------- is reduced to 
sv I ner, the p is lengthened, indicating the possible presence of 
a stronger then normal syllable boundary. This stronger boundary. 
would then prevent the from changihg the g to an - m under 
Progressive Assimilation. An alternative is to hare a "strong 
syllablew boundary symbol which would be "strongerwq than a "weak 
wordm bounaary symbol, but this woulil be mdssy and unnatural. 
It voola probably be more productive to represent fast 
speech forms with phonemes utilizing multi-valued (1 through 7 
instead of + and ) features. Giving the segments length 
attributes would allow segments to be deleted by a combination of 
rules which reduce segment lengths. Also, in conparing forms, a 
very short seqment could be considered to be deleted. 
Fast speech rules seem to be selective as to the words to 
which they can apply. Zwicky (14) gives examples and counter- 
examples for various fast speech rules; However, it seems that 
the counter-examples are words which do not ftequently occ,ur in 
&aqua1 speech, while the examples were common. This ooint was 
illustrated when , in an early run, that Schva Deletion produced 
/k ae n + g r u/ from 'tkangaroow, AT first, this East speech 
form was unacceptable, but with use, it becdme more and more 
acceptable. Interestingly enough, a small random polling se;ned 
to indicate that this form is acceptable "if yout re an 
AUS traliantr . That fast speech rules apply t~ what 1s common in 
the speaker's vocabulary is also evidenced by the heavy 
application of fast speech rules to local names. 
The similarity af the palatization rules in this fast spaecfi 
grammar and in normal Fnglish (1) raises tha question of What 
are 'fast speech rules?". If normal rules are restricted versions 
of the more general processes which also account for the Past 
speech forms (14), then we must be careful in using slow speech 
surface forms to test the fast speech rules. For example, part 
of the data covered by the Schwa Deletion rule might actuslly 
result from schwas being *ser&gq between consonants in slow 
speech formS. 
york was supported undec National Science Fou\naaaiion 
1309, with the supervision and quidanc~ of Joyce 

References 
sky, Noam G Yorr~s Halle, The S2gm&-Pattern of E2gL~l.&, 
rper and Row, Yew York, Yew York, 1968 

Re P.S. & R. L. Mercer, Y"e Phonological Component of 
P Automat ic S~eech-Recognition Systemff, Contributed 
ears. - IEFE Sypl~osium on Speech Recognition, Lee Erman 
B, 1974 

mlan, Joyce a nd Yve s Ch. norin, ghonejhqiial c;rggmgg 
Description, 
B Per: ------ Ra tural Language Studies No. 9, 
~notics Laboratory, The University of Michigan, 1971 

Ilk an, J-oyce, vaCcmpu ter Exploration of Fast Speech 
Iesm, IEEE Transactions on Acoustics, Speech and Signal 
$Zessig.q, ASSP-23, 1, February 1975 

II., wContradiction, Delction and Inherent Variability 
bhe Enqlish Copulaw. Lanquage, - 45, pp 715-64 

6. Neu, Helene, "Some Optional Phonological Rules Occurring in 
Casual S peech", Speecn tomaunidation Research Laboratory, 
Santa Barbara, Califorria, SUR Note 95, NIC 17677, 
July 11, 1973 

7. Neu, Helene anll Beatrice Oshika, *Optiohal Phonological 
Rules - Revisions an? Additions", Speech Comrnunica Lions 
Research Laboratory, Santa Barbara, California, SUR Note 
122, NIC 21717, February 5. 1974 

8. OIMalley, Michael H. and Alan Cole, 'Vesting Phonological 
Rulesm, Contributed Papers - IEEE Symposium on Speach 
Recognition, Lee Erman (ed) , 1974 

9. Oshika, Beatrice f., Victor W. Zue, Rollin V. Weeks and 
Helene Neu, "The Role of Phono-logical Rules in Speach. 
Understanding Researchd, IEEE Transactions on Acoustics, 
Speech and Signal Processing, ASSPd23, 1, February 1975 

10. Robinson, Jane J, , wPerformance GramatarsM, Technical Note TN 
97, Stanford Research Institute, 197U, to 'appear in S-eeech 
presented at the, 1974 IEEE 
Recos~i~~I~~fiedPapers-- ------------------ ----- --- 
Syemosi urn Acaden ic Press 

11. Shockey, Linda, unpublished collection of rules, Dept. of 
Computer Sci,ence, Carnegie-Mellon University, Pi ttsbgrgh , 
P'enna. 

12, Weeks, Rollin V., '9s DC Phonological Rulesw, Systems 
D~~elopment Cbrp., SUR Note t19, NIC 21490, January 31, 
1974 

13. Zue, Victor, W., "Optional Phonological Rulesn, MIT Lincoln 
Laboratory, Lexington, Mass., SUR Note 124, NIC 21952, 
Feb~uary 19, 1974 

14. Zwicky, Arnold N., "Note on a ~honological Hierarchy in 
Xngl,ishit , in R. P. Stockwell and R. K. S. ~acaulay 
(eds .) , L&hquist & Chan4e and Gen9ratij.e Theory, Indiana 
Unive~sity Press, Blocwington, 1972 
