We have two problems with regard to sound--whether the witnesses have
heard correctly, and whether we hear them correctly. Between both
witnesses and ourselves there are again other factors. Correct
comprehension, faithful memory, the activity of the imagination, the
variety of influences, the degree of personal integrity; but most
important is the consideration, whether the witness has heard correctly.
As a general thing we must deny in most cases completely accurate
reproduction of what witnesses have heard. In this connection dealing
with questions of honor is instructive. If the question is the recall of
slander the terms of it will be as various as the number of witnesses.
We discover that the sense, the tendency of slander is not easily
mistaken. At least if it is, I have not observed it. The witness, e.g.,
will confuse the words “scamp,” “cheat,” “swindler,” etc., and again the
words: “ox,” “donkey,” “numbskull,” etc. But he will not say that he has
heard “scamp” where what was said was “donkey.” He simply has observed
that A has insulted B with an epithet of moral turpitude or of stupidity
and under examination he inserts an appropriate term. Often people hear
only according to meanings and hence the difficulty of getting them to
reproduce verbally and directly something said by a third person. They
always engage upon indirect narration because they have heard only the
meaning, not the words. Memory has nothing to do with this matter, for
when in examination, a witness is requested to reproduce directly what
he has just heard, he will reproduce no more than the sense, not the
words. Not to do so requires an unusual degree of intelligence and
training.
Now if the witnesses only reproduced the actual meaning of what they
heard, no harm would be done, but they tell us only what they _suppose_
to be the meaning, and hence we get a good many mistakes. It does seem
as if uneducated and half-educated people are able to shut their ears to
all things they do not understand. Even purely sensory perception is
organized according to intelligent capacity.
If this is kept in mind it will be possible correctly to interpret
testimonies in those difficult instances in which one man narrates what
he has heard from another concerning his own statement, and where it
might be quite impossible to judge the nature and culture of this third
person. There are a few other conditions to consider besides.
If we have to discover a person’s hearing power or his hearing power
under definite conditions, it is best never to depend, in even slightly
important cases, on vocal tests merely. The examination must be made by
experts, and if the case is really subtle it must be made under the same
circumstances of place and condition, and with the same people as in the
original situation. Otherwise nothing certain can be learned.
The determination of auditory power is, however, insufficient, for this
power varies with the degree any individual can distinguish a single
definite tone among many, hear it alone, and retain it. And this varies
not only with the individual but also with the time, the place, the
voice, etc. In my bed-room, e.g., and in three neighboring rooms I have
wall-clocks each of which is running. The doors of the room are open
right and left. At night when everything is quiet, I can sometimes hear
the ticking of each one of these clocks; immediately isolate one
completely and listen to that so that the ticking of the other three
completely disappears. Then again I may kindly command myself not to
hear this ticking, but to hear one of the other three, and I do so,
though I fail to hear two clocks together at just the same instant. On
another day under similar circumstances I completely fail in this
attempt. Either I hear none of the clocks in particular, or only for a
short time, which results in the ticking’s being again lost in the
general noise; or I do hear the ticking of one clock, but never of that
which I have chosen to hear.
This incident is variously explicable and the experiment may be repeated
with various persons. It indicates that auditory capacity is exceedingly
differentiated and that there is no justification for aprioristic doubt
of especial powers. It is, however, admittedly difficult to say how
experiments can be made under control.
There are still a few more marvels. It is repeatedly asserted, e.g., by
Tyndall, that a comparatively large number of people do not hear high
tones like the chirping of crickets, although the normal hearing of such
people is acute. Others again easily sense deep tones but distinguish
them with difficulty because they retain only a roll or roar, but do not
hear the individual tones.[182] And generally, almost all people have
difficulty in making a correct valuation of the direction of sound.
Wundt says that we locate powerful sounds in front of us and are
generally better able to judge right and left than before and
behind.[183] These data, which are for us quite important, have been
subjected to many tests. Wundt’s statement has been confirmed by various
experiments which have shown that sound to the right and the left are
best distinguished, and sounds in front and below, in front to the right
and to the left, and below, to the right and to the left, are least
easily distinguished. Among the experimenters were Preyer, Arnheim,
Kries, Münsterberg.
All these experiments indicate certain constant tendencies to definite
mistakes. Sounds in front are often mistaken for sounds behind and felt
to be higher than their natural head-level. Again, it is generally
asserted that binaural hearing is of great importance for the
recognition of the direction of sound. With one ear this recognition is
much more difficult. This may be verified by the fact that we turn our
heads here and there as though to compare directions whenever we want to
make sure of the direction of sound. In this regard, too, a number of
effective experiments have been made.
When it is necessary to determine whether the witness deposes correctly
concerning the direction of sound, it is best to get the official
physician to find out whether he hears with both ears, and whether he
hears equally well with both. It is observed that persons who hear
excellently with both ears are unfortunate in judging the direction of
sound. Others again are very skilful in this matter, and may possibly
get their skill from practice, sense of locality, etc. But in any case,
certainty can be obtained only by experimentation.
With regard to the conduction of sound--it is to be noted that sound is
carried astonishingly far by means of compact bodies. The distance at
which the trotting of horses, the thunder of cannons, etc., may be heard
by laying the ear close to the ground is a common-place in fiction.
Therefore, if a witness testifies to have heard something at a great
distance in this way, or by having laid his ear to the wall, it is well
not to set the evidence aside. Although it will be difficult in such
cases to make determinative experiments, it is useful to do so because
the limits of his capacity are then approximated.
Under certain circumstances it may be of importance to know what can be
heard when the head, or at least the ear, is under water. The experiment
may be made in the bath-room, by setting the back of the head under
water so that the ears are completely covered but the mouth and the
eyes are free. The mouth must be kept closed so that there shall be no
intrusion of sound through the Eustachian tube. In this condition
practically no sound can be heard which must _first pass through the
air_. If, therefore, anybody even immediately next to you, speaks ever
so loud, you can hear only a minimum of what he says. On the other hand,
noises that are conducted by compact bodies, i.e. the walls, the bath,
and the water, can be heard with astonishing distinctness, especially if
the bath is not detachable but is built into the wall. Then if some
remote part of the building, e.g. some wall, is knocked, the noise is
heard perfectly well, although somebody standing near the bath hears
nothing whatever. This may be of importance in cases of accident, in
certain attempts at drowning people, and in accidental eaves-dropping.
There are several things to note with regard to deaf persons, or such as
have difficulty with their hearing. According to Fechner, deafness
begins with the inability to hear high tones and ends with the inability
to hear deep ones, so that it often happens that complainants are not
believed because they still hear deep tones. Again, there are mistakes
which rise from the fact that the deaf often learn a great deal from the
movements of the lips, and the reading of these movements has become the
basis of the so-called “audition” of deaf mutes. There are stories of
deaf mutes who have perceived more in this way, and by means of their
necessary and well-practised synthesis of impressions, than persons with
good hearing power.
The differences that age makes in hearing are of importance. Bezold has
examined a large number of human ears of different ages and indicates
that after the fiftieth year there is not only a successive decrease in
the number of the approximately normal-hearing, but there is a
successively growing increase in the degree of auditory limitation which
the ear experiences with increasing age. The results are more surprising
than is supposed.
Not one of 100 people over fifty years of age could understand
conversational speech at a distance of sixteen meters; 10.5% understood
it at a distance of eight to sixteen meters. Of school children 46.5%
(1918 of them) from seven to eighteen understood it at a distance of 20
meters plus, and 32.7% at a distance of from 16 to 8 meters. The
percentage then is 10.5 for people over fifty as against 79.2 of people
over seven and under 18. Old women can hear better than old men. At a
distance of 4 to 16 meters the proportion of women to men who could hear
was 34 to 17. The converse is true of children, for at a distance of 20
meters and more the percentage of boys was 49.9 and girls 48.2. The
reason for this inversion of the relation lies in the harmful influences
of manual labor and other noisy occupations of men. These comparisons
may be of importance when the question is raised as to how much more a
witness may have heard than one of a different age.