Fairbanks, Grant. Experimental Phonetics – T27

A Study Of Minor
Organic Deviations In ‘Functional’ Disorders
Of Articulation: 3. The Tongue *1

Grant Fairbanks
Betty Bebout **2

The present article reports a portion of
the results of an investigation which has
attempted to provide preliminary answers to
two questions: Arc there organic differences
between persons with ‘functional’ articulatory
disorders, as ordinarily classified, and
persons without disorders? If so, what are
sonic of the specific differences?

The first report of the series (3) included
a discussion of the problem and a detailed
description of the methods employed in
selecting the subjects, 60 young adults who
constituted the following four groups: 15
males and 15 females with superior consonant
articulation; 15 males and 15 females
with inferior consonant articulation. Selection
was at random from the extremes of
articulatory ability, as determined by screening
and testing; all ‘organic’ and certain
‘functional’ types of speech disorders were
excluded. Subjects were brought into the
laboratory individually for a number of
measurements and estimates of (1) the rate
of movement of oral structures, (2) the
lips, (3) the tongue, (4) the teeth and hard
palate, and (5) hearing. The results, too
lengthy for a single article, are presented
in a series corresponding to these five divisions,
with summarization and interpretation
reserved for the final paper. The first
two divisions have already been reported
(2, 3).

Procedure

In this portion of the study, four
measurements of the tongue were
made: (1) Maximum length of protrusion;
(2) length of the tip; (3)
maximum amount of tongue force;
(4) percentage of error in duplicating
a tongue position.

Measurement of maximum protrusion
was done by placing one end of
a tongue blade against the labial surfaces
of the lower central incisors, instructing
the subject to extend his
tongue as far as possible along the
blade, marking the maximum point
reached, and measuring the distance
to the nearest millimeter. As an index
of reliability the measure was performed
twice on 26 adults, four weeks
intervening between repetitions. The
rank-difference correlation between
the two sets of data was .75.

The length of the tongue tip was
defined as the distance forward of the
anterior margin of the frenulum. The
end of a tongue blade was placed at
this margin and the subject was instructed
to relax his tongue and extend
it along the tongue blade. The
position of the tip was marked and
the distance measured in millimeters.
Between independent measurements of
20 adults on two consecutive days the
rank-difference correlation was .98.221

Tongue force was measured by
means of the apparatus shown in
Figure 1. The upper portion of the
diagram shows the arrangement as
seen from the front. The subject
rested his upper teeth on a tongue
blade, I, placed the indentation of his
chin against a padded bar, J, and
pressed forward with his tongue
against a metal tongue disc, E. The
tongue disc was adjusted arbitrarily
to a distance of five millimeters from
the lower incisors. The lower portion
of Figure 1 is a side view. An L-shaped
lever, A, with its axis at B,
was counter-weighted to equilibrium
by a block of lead, C. The effective
length of the vertical arm, from B to
the tongue disc, E, was 10ʺ, while the
horizontal arm was notched as shown
at 31 one-inch intervals. Lateral movement
of A was restrained by two
metal stops, D. In its basic position
the vertical arm of A rested against a
contact, H, and opened the circuit to
a buzzer. The circuit was made and
the buzzer sounded when the pressure
of the tongue against E, which
was fastened to A as shown, broke
the contact of A and H. Operation
was similar to a lever scale. Two
hooked weights of 1.0 and 0.5 kilograms
each were provided, and either
or both hung at the appropriate distance
on the horizontal arm of the
lever. Figure 1 shows a weight, F,
hung at 3ʺ. With the distance from
B to the tongue disc, E, equal to 10ʺ,
tongue force in kilograms may be
taken as equal to the distance of the
weight from B, in inches, rimes one-tenth
of the weight in kilograms. Since
the distance range was 31ʺ and the
weight combinations were 0.5, 1.0, or
1.5 kilograms, the total range of the
apparatus was 0.05 to 4.65 kilograms.
This range was found to be appropriate
by preliminary exploration; in
the experiment the obtained range was
0.75 - 4.50 kilograms.

Measurement of the percentage of
error in duplicating a tongue position
was made because of the finding of
Carrell (1), who tested the ability of
children to learn a standard pull and
found a difference in favor of normal
speakers. In the present instance the
subject's task was to learn to protrude
his tongue a distance equal to one-half
the length of his individual maximum
tongue protrusion. A vertical
stop, 16 mm. high and 20 mm. wide,
was fastened to a tongue blade at this
distance and the end of the tongue
blade held against the lower incisors.
Having been instructed, the subject
extended his tongue to the stop 10
222times in succession; the. stop was then
removed and he attempted to duplicate
the distance. Measurement of
error was made in millimeters and expressed
as a percentage of the attempted
distance. The above procedure
was repeated three times, once
after each of the other measurements,
and the mean of the three trials was
used for the calculations.

In addition to the above measurements,
estimates were made of the
size and shape of the tongue. Size
was judged as small, average, or large
in relation to the lower dental arch;
shape was described as flat or bulged.
Subjects were instructed to relax the
tongue and open the mouth. On two
independent sets of judgments of 50
adults self-agreement was 94 per cent
for size and 78 per cent for shape.

Results

The results of the measurements
may be seen in Table 1, which shows
means and standard deviations, and
in Table 2, which summarizes the
analysis of variance. The differences
between means are generally small,
inconsistent in sign, and in no instance
does a difference between ability
groups, sex constant, reach significance.
In the case of maximum force,
the differences between sex groups in
favor of the male are substantial. For
this measure the F of 12.42 in the first
column of Table 2 exceeds the 1%
value, while the ratio of 36.07 in the
third column, also larger than the
1% value, shows that the significant
variance between groups may be attributed
to sex differences.

Table 3 presents the results of the
estimates of relative size and shape of
the tongue. In the left half of the table
the basic groups have been combined,
first according to ability and then according
to sex. Data for the four basic
groups of 15 subjects each are shown
at the right. The frequencies are too
small for satisfactory statistical interpretation
and detailed comment is not
justified, but the findings appear to be
essentially negative. For purposes of
future investigation one possible exception
may be recorded, namely, the
mild indication that distributions according
to size and shape may be
atypical in males with inferior articulatory
ability.

Summary

References

1. Carrell, J. Etiology of sound substitution
defects. Speech Monogr. 1937, 4,
17-37.

2. Fairbanks, G. and Green, E. M. A
study of minor organic deviations in
‘functional’ disorders of articulation:
2. Dimensions and relationships of the
lips, JSHD, 1950, 15, 165-168.

3. Fairbanks, G. and Spriestersbach, D. C.
A study of minor organic deviations in
‘functional’ disorders of articulation:
1. Rate of movement of oral structures.
JSHD, 1950, 15, 60-69.225