"DIGITAL SPEECH AID TO DECREASE STUTTERING

-CLINICAL RESULTS AND PATIENTS' REACTIONS"

Andrzej Czyzewski  &  Bozena  Kostek
Technical University of Gdansk
Sound  Engineering  Department
ul.Narutowicza 11/12,80-952 Gdansk,Poland

Marek  Roland - Mieszkowski
Digital Recordings - Advanced R & D
5959 Spring Garden Rd., Suite  1103
Halifax, Nova Scotia B3H-1Y5,Canada

Copyright 1990-1994, Digital Recordings
Halifax, Nova Scotia, Canada


Introduction
************

New electronic aid / training device to reduce
stuttering  was developed. Clinical tests on about 60
patients showed, that  the  DSA (Digital Speech Aid)
is effective in helping to combat stuttering by itself
or in combination with other standard and non-standard
methods [1]. The majority of "Classical Stutterers"
become more fluent when using this device.  Device
is relaxing and non-disturbing. With DSA a person
can speak in any fashion and at any rate.

DSA is based on advanced DSdP (Digital Sound
Processing)  technology using the latest electronic
DSP technology. The software developed for the
device exploits new approach to stuttering disorder.
With DSA many stuttering people can speak fluently
(or more fluently) in any fashion and at any rate.

Results of the DSA testing supports authors' theory,
that stuttering is a physiological disorder, in most
cases of a neurological basis. Stutterers become
nervous because they stutter (not as believed by
some, that they stutter since they are nervous).


Clinical testing of Digital Speech Aid (DSA)
********************************************

Authors decided to test DSA in real life situations,
rather than in artificial,  laboratory-based. There are
two major reasons for this :

* Very often results in the laboratory introduce
  unrealistic environment, which does not predict at all
  if the device or technique will be effective in other
  situations, where other conditions such as : stress,
  multitasking, different auditory conditions etc may
  play important role.

* Effects of DSA are sometimes not noticable or
  significant at the first trials. Our experiments
  indicate, that 4 to 6 weeks are required to obtain full
  benefit of given type of DSdP processing.In all clinical
  cases improvement was observed with similar time scale.
  No decrease of effectiveness was observed as predicted
  by some people familiar with our early research.

Above mentioned reasons require portable device to
perform experiments. This was the reason that DSA
was reduced, despite its' complexity to very small
size. This allowed authors to perform experiments
investigating long-term effects. Also DSA was
designed with very powerful hardware, capable to
implement all existing algorithms and many new ones,
which are currently under investigation [3].
Currently, DSA is most effective in the case of
"Classical Stutterers" who consist about 80% -> 90%
of the stuttering population. Significant improvement
or total fluency is observed in about 40% -> 60%  of
"Classical Stutterers" during the text reading. Rest
of them also improve to various degrees. Improvements
were also observed in all situations : in the office,
at home, on the telephone, during public meetings,
presentations, good and bad days,  etc.  Improvement
is instant, however, we observe increase in
effectiveness during the first 2 -> 6 weeks (this is
consistent with other similar observations and could
be explained in author's opinion on the bases of
neural networks, which could be used as the model of
inner-working of the auditory system). After that it
seems to remain the same. In majority of cases there
is a carryover effect - person remains more fluent
for 2 hours -> 2 weeks after using DSA. Significant
improvement in self-esteem and self-confidence are
observed. People like to use DSA and say that it is
relaxing. Many people also indicate, that they feel,
that they cannot stutter. Long term effects seem to
support authors' theory and expectations - DSA  is
still effective (same level) after being used for 10
months.


First clinical trials - June 1992
*********************************

First prototypes of DSA (II generation) were finished
in May 1992. Some of the first clinical trials were very
exciting and the device met with good approval from
the stuttering people. Here are some of the remarks
from this early study in Poland :

* Testimony from speech pathologist : " ...I think that
  Digital Speech Aid (DSA)is extremely effective in the
  elimination of stuttering, even in  cases  of very
  severe stuttering. ....During my 30-years long
  practice as a speech pathologist, no technique was
  as successful. I believe that we finally have the
  green light for people who have till now  problems
  with elimination of stuttering ...We are waiting very
  anxiously for DSA to appear on the market and
  become available for all stuttering people......"
  Halina Stawikowska, Speech Pathologist, June 04,
  1992.

* "....Speaking with DSA  brought me big relief. I
  realized, that I can also speak like normal person, at
  relatively fast rate.All the sudden I got new surge of
  power.....This device helped me also in the
  inter-personal contacts. I am not afraid anymore !..It
  is fantastic to realize, that spoken word does not
  have to be "bumpy". Thank you , thank you, thank
  you !!!....", Anna Grudzien, 21 years old, June 05,
  1992.

* ".... Speaking with DSA eliminates prolongation of
  vowels, speech becomes more fluent...Improvement
  is very good, much better then with the DAF
  (Delayed Auditory Feedback). In my case it was
  particularly noticeable in the German language,
  which I am studying and in which I stutter much
  more often then in the Polish language. While
  reading in German, with DSA I did not stutter at
  all....", Jacek Szot, 24 years old, June 03, 1992.

* "... I think, that use of DSA is relaxing.It is
  difficult to stutter. I could speak fast without
  stuttering. Normally I speak slow......", Prof.
  Antoni Stawikowski, Astrophysics, May 31, 1992.

* ".... With DSA one can speak fast ,with any chosen
  speed. I went with this device to do shopping and I
  could speak very well.I am sure,that if I would have
  this device my speech will improve...", Lukasz
  Jaskolka, 15 years old, June 04, 1992.

* "..... using DSA I feel, that I cannot stutter and I
  am not nervous. On the beginning, I did not believe
  that I can stop to stutter. After use of this device
  I got back my confidence... Stuttering people must
  always speak slow, however I am not used to do that.
  Using this device I can speak very fast.....", Emila
  Davidek, 13 years old, June 04, 1992.

* ".... when I tried this invention I started to feel
  unconstrained, free, I am not stressed and I do not
  stutter.This device is very good..", Marek Struk, 9
  years old, June 04, 1992.


Long term effects - DSA (III-d generation model)
************************************************

Long-term effects were and are tested right now. The
initial results are very encouraging. It is expected that
due to the relaxing and reassuring effect of DSA, the
base-line stuttering level will decline (we observed
this already in some cases).  The effectiveness of the
device is expected to remain the same for removal of
the "natural level" of stuttering. In a sense DSA is
expected to work as a prosthetic device, similar to
hearing aid.  It does not mean however, that it has to
be worn all the time. It can be only used several hours
per day, in the most difficult situations and as a
backup (many of our subjects are using it in this
mode). Below are some remarks from some patients
who did use DSA for over period of 3 to 10  months :

* "....I am very happy with DSA. Used it day to day
  and my speech has improved 80 %. I have used
  DSA to speak at approx. twenty (20) meetings as I
  am president of a Legion in Dartmouth, N.S......I
  recommend DSA 100%....." John Dunphy,
  Dartmouth, Nova Scotia, Canada, November 18,
  1993.

* "...my experience with DSA for past 7 months has
  been good....In past years talking on the phone was
  my reason to be nervous to speak to people. With
  DSA I now find it to be no problem to answer a
  phone and have a normal conversation. I
  recommend DSA for anyone with a speech
  stoppage and stuttering." John Dunphy, Dartmouth,
  Nova Scotia, Canada, March 25, 1994.

* "Overall the device has been very helpful...I have
  improved the most on the telephone; I would often
  avoid words, but with the device I hardly stutter...
  I am not as apprehensive about my stuttering as
  before and my speech has improved a great deal.
  I have also noticed an increase in my self-esteem
  since wearing the device...I feel more confident in
  speaking situations and do not avoid words.... For
  the first few weeks (3-4), my speech was improving
  at a steady rate. At about one month, my level of
  fluency seemed to level off and I have maintained
  the same level of fluency since that time...." 25
  years old female stutterer, Halifax, Nova Scotia,
  Canada November 18, 1993.

* "..Over the course of a few months, I became very
  comfortable with the speech device (DSA). ...I have
  less apprehension with "feared words" and stutter
  quite a bit less than before using the device. My
  confidence in speaking has improved over the time
  I used the device and the "carry-over" time has also
  increased. My fluent speech will last sometimes
  half a day without the device." 25 years old female
  stutterer, Halifax, Nova Scotia, Canada, December
  19, 1993.

* "The DSA machine has really opened up a new
  world for me. It has provided me with a new sense
  of freedom now, by allowing me to speak without
  fear, of so many things. The most significant
  revelation is being able to use the telephone and
  call people and places I haven't been able to.... The
  DSA has given me so much comfort in my speech
  and day to day life by gently allowing me to speak
  and say words that I have avoided for many, many
  years. It is truly a great invention and a miracle for
  someone like myself who felt I would spent the rest
  of my life hiding from many situations." Lori Paruch,
  Halifax, Nova Scotia, Canada, January 14, 1994.

* "When I first began to use the DSA I noticed a
  dramatic increase in my fluency when speaking
  especially on the phone.....It has been so wonderful
  to have the freedom of not being afraid to use the
  phone, to call to make appointments etc.....My life
  has changed now since I have used DSA.....it is a
  wonderful machine to use." Lori Paruch, Halifax,
  Nova Scotia, Canada, April 04, 1994.


Comparative study of various methods for the
********************************************
modification of the auditory feedback loop
******************************************

As the elaborated prototypes of the DSA are
implementing various algorithms for the modification
of the auditory feedback loop,thus some studies were
carried out to enable the comparison of the
effectiveness of individual methods. The DSA
prototypes were implementing masking noise (MAF),
delayed auditory feedback (DAF), frequency altered
feedback (FAF) [4,5]  and digital discorrelation
filtering - the algorithm elaborated by the authors
[3] and various combinations of the above algorithms.
Results of an exemplary testing session are presented
in the Tab. 1 and in Fig. 1,2,3.

Tab.1 Number of errors occured during the testing session

Patient   Direct   MAF   discorrel.    discorrel.   FAF   FAF+DAF
          speech         filtering 1   filtering 2

Filip       23      9        9             12        5       2

Jacek       24     10       22             29       10       2

 ukasz       8      2        2              4        1       0

Krzysztof   10      3        9             13       7F       0


     *** Fig. 1 ***

Fig. 1 Number of errors for individual patients according to Tab.I.

     *** Fig. 2 ***

Fig. 2 Relative number of errors expressed in [%].

     *** Fig. 3 ***

Fig. 3 Comparison of results obtained with all methods.


Conclusions
***********

DSA was designed with very powerful hardware,
capable to implement all existing algorithms and
many new ones, which are currently under
investigation The elaborated prototypes of the DSA
are provided with 256 settings to be selected by the
operator or by the user.  Currently, DSA is most
effective in the case of "Classical Stutterers" who
consist about 80% -> 90% of the stuttering population.
Significant improvement or total fluency is observed
in about 40% -> 60%  of "Classical Stutterers"
particularly during the text reading. Rest of them also
improve to various degrees.  Long term effects seem
to support authors' theory and expectations - DSA  is
still effective (same level) after being used for 10
months. Consequently, the authors are of the opinion
that the progress in modern digital signal processing
technology may cause considerable impact to the
reduction of stuttering.



References
**********

[1]    Hermes Electronics, internal report "The Digital
       Speech Aid", Halifax, Nova Scotia, Canada, December
       1993.

[2]    Howell P., Nirit El-Yaniv, Powell D. J.: "Factors
       Affecting Fluency in Stutterers when Speaking under
       Altered Auditory Feedback",  Speech Motor Control and
       Stuttering. Excerpta Medica Nr 9 1991, chapter 28.

[3]    M. Roland-Mieszkowski et al.: DSA (Digital SpeechAid)
       - A New Device to Decrease or Eliminate Stuttering.Paper
       presented at 1st World Congress on Fluency Disorders,
       Munich, Germany, 1994.

[4]    Howell P.: "Changes in voice level caused by several
       forms of altered feedback in fluent speakers and stutterers,"
       Language and Speech, 1990, 33(4), pp.5-338.

[5]    Webster R. L.: "Manipulation of vocal tone: implications
       for stuttering", Speech Motor Control and Stuttering.
       Excerpta Medica No., 1991.