Note: Descriptions are shown in the official language in which they were submitted.
CA 02320214 2000-08-08
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Title
EARPHONE WITHOUT IMPULSE NOISE FOR PROTECTION AGAINST
CONDUCTIVE HEARING LOSS
Field of the Invention
The present invention relates to an earphone without impulse noise for
protection
against conductive hearing loss, which can prevent the sound waves direction
of loudspeaker
thereof is not directly transmitted to the tympanic membrane located in the
most inner side of
external auditory canal. The middle ear can be protected against conductive
hearing loss caused by
the direct impact of the sound pressure.
Background of the Invention
It is conventionally know that the sound is defined as a physical energy and
is
transmitted in the form of energy. The farther the sound travels the greater
energy it contains (like
thunder or sound from gunshots). Therefore, energy in the sound is measured by
the logarithm
system while decibels) is often used as the unit to measure the sound
intensity. However, the
"decibel'' is not an absolute value, but a relative value, such that the
decibel means a comparison
of the intensity between two sounds. Hence, if we say how many decibels a
sound has, it means
that how many times its pressure greater than a certain reference one. When an
audiometer is used
to measure the hearing and the decibels increase from 0 to 60, it is indicated
that the energy in the
sound increases by 106. However, even a sound pressure with 60 decibels isn't
a loud sound, and
it's nearly equal to a great sound a few feet away from us in our daily life.
A human ear, as shown in Figs. 1 to 3, consists of three main parts - the
external ear 10,
the middle ear 20, and the inner ear 30. The external ear 10 includes the
helix 11, the antihelix 12,
the auricle 13, the conchs 14, the antitragus 15, the tragus 16, and the
external auditory canal 17
whose length of an adult is about 24mm. The tympanic membrane 171 is located
in the most inner
side of the external auditory canal 17. The external auditory canal 17 and the
middle ear 20 are
separated by the tympanic membrane 171 while the middle ear 20 is the ear drum
formed between
the external ear 10 and the inner ear 30 and having the malieus 21, the incus
22 and the stapes 23,
wherein the end of the malleus 21 lies hidden in the tympanic membrane 171
while the body of
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the malleus 21 and the head of the incur 22 are joined together to be a joint.
Besides, the incur 22
has a short leg 221 and a long leg 222, wherein the short leg 221 leans on the
wail of the ear drum
while the end of the long leg 222 is linked to the head of the stapes 23. The
end of the stapes 23 is
formed as a foot shape, as shown in Fig. 2.
Moreover, the inner ear 30 includes the cochlea 31 and the labyrinth 32,
wherein the
cochlea 31 controls the human hearing system while the labyrinth 32 maintains
balance in the
body. These two fine parts are enclosed by a capsule; in addition, some
periiymphs in the most
outer layer thereof cover the cochlea 3l and the labyrinth 32. These
perilymphs are functioned as
an air cushion to provide an excellent protection when the head gets an
intense vibration. In fact,
the cochlea 31 and the labyrinth 32 are floating in the fluid of the lymphs.
The inside of the
cochlea 31 consists of three parts - the scala vestibuli, the scala tympani,
and the cochlear duct
containing perilymph. The nerve cells in the cochlea 31 contain about 30.000
hairlike nerve
endings. Besides, the oval window 33 and the round window 34 ace located near
the wall surface
of eardrum of the middle ear 20 while the base of the stapes rests against the
opening of oval
window 33 and the inner side thereof is attached to the scala vestibuli 311 of
the cochlea 31 so
that the cochlea 31 can receive the sound pressure transmitted from the
auditory ossicles while the
round window 34 is attached to the scala tympani 312 of the cochlea 31 in
order to directly receive
the sound transmitted from the eardrum of the middle ear 20.
Furthermore, after the sound pressure is transmitted from the tragus 17 to the
tympanic
membrane 171, a portion of the sound pressure is partially reflected back to
the tragus 16 while
another portion of the sound pressure passes through the tympanic membrane 171
into the middle
ear 20. The portion of the sound pressure that has been transmitted into the
middle ear 20 has a
certain part pass through the malleus 21 and the incur 22 into the foot-shaped
end of the stapes 23
(those who consist of the maileus_2.1,-the-incur 22, and the stapes 23 is
hereafter called auditory
ossicles), and then through the oval window 33 into the cochlea 31 of the
inner ear 30. The rest of
the sound pressure is transmitted by the air medium in the eardrum into the
cochlea 31 of the inner
ear 30.
Consequently, the sound pressure transmitted into the human ear is divided
into two
parts to enter the inner ear 30; however, the sound transmitted by the way of
auditory ossicles into
the oval window 33 is more effective and important than that transmitted by
the air medium
through eardrum into the round window 34. The reason is that 99.9% of the
energy of the sound
pressure transmitted into the eardrum of the middle ear 20 and passing by way
of the air medium
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through the round window 34 into the perilymph of the cochlea 31 is consumed
or reflected back
by the fluid surface. Only 0.1% of the energy is able to pass through the
perilymph into the
cochlea 31.
Accordingly, the most effective way of the sound transmission is carried out
from the
tympanic membrane 171 through the auditory ossicles into the oval window 33.
However, when
the sound pressure is transmitted to the end of the stapes 23 and strikes the
oval window 33, it
directly passes through the incompressible perilymph into the cochlea 31 while
the sound pressure
is not consumed or reflected by the fluid surface. Presently, the perilymph
containing the sound
pressure stimulates the hairlike nerve endings in the cochlea 31 to generate a
displacement or a
bending, and this motion can turn the mechanical force in the sound pressure
into electrochemical
impulses that are carried up the acoustic nerve to auditory cortex of the
brain. At last, it is the
sound we can understand.
In view of the above, we realize that sense of hearing of the human ear is
generated by
the movement of the hairlike nerve endings, that even a slight displacement of
the hairlike nerve
endings causes the sense of hearing. Therefore, the sense of the human ear is
very sharp and the
perceptible pitch is also very wide. Generally, the perceptible frequency
range of human beings is
about 20~20000Hz while the intensity range 10-'Z~lO2W/m2 and the sound
pressure less than
180dB. However, not all perceptible sounds are suitable for the human ear to
receive. The pitch in
the improper range (sound pressure over 90dB is so-called noise) easily causes
the damage of the
auditory part in the ear. The factory workers under a long-time exposure to
the industrial noise
without wearing any hearing protectors (like earplug or earphone) have the
hearing damage
possibility up to 25% after a few years.
The reason lies in that the sound pressure of the industrial noise stimulates
the hairlike
nerve endings in the ear to generate a displacement or a bending. They return
to the original state
when leaving this noise circumstance for a period. The restoring effect of the
hairlike nerve
endings worsens more and more with the time and causes the hearing damage in
the inner ear.
This kind of hearing loss mostly belongs to the perceptive hearing threshold
while the other kind
is mostly caused by a direct strike on the head or an instant impulse noise,
resulting in a damage of
the ear membrane or the auditory ossicles so that the sound pressure
transmitted in the middle ear
20 simultaneously enters the oval window 33 and the round window 34 in the
vestibuli 33 and it is
counteracted by each other. Accordingly, a hearing loss is caused. This kind
of conductive
function loss in the middle ear is called conductive hearing loss.
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Obviously, the hearing loss resulting from the above mentioned kind of
conductive
function loss in the middle ear increases in these years, and most of them are
the young people
using Walkman. It is well-known that the loudspeaker of the common
stereophonic sound or the
earphone is driven by the current connected by the electric cord so that the
conic paper box on the
front part and the vibrating membrane generate a to and fro vibration to
produce sound and music.
A complicate physical phenomenon is produced by this simple, to and fro
repetitive movement
that the air is compressed when the conic paper box on the front part and the
vibrating membrane
move forward so that the molecules in the air become dense to be the high
pressure air while the
molecules in the air are thinned to be the low pressure air when the conic
paper box on the front
part and the vibrating membrane move backward.
However, the air molecules have the same characteristics as we don't like to
be
compressed and squeezed, so that an elasticity is generated by the squeezed
air to push the energy
produced by the loudspeaker to a farther place. When the loudspeaker proceeds
with the to and fro
movement, the adjacent air pushes the energy forward by this loudspeaker. This
energy pushing
the sound transmission is called "sound pressure".
Accordingly, the sound energy transmission is a continual connection between a
high
pressure space and a low pressure space. This pressure space as the wave
includes the wave peak
and the wave valley which move forward unceasingly, so that the moving
direction of the sound
produced by the loudspeaker is completely driven by the sound pressure and the
people in the
farther place is also able to hear the sound or music produced by the
loudspeaker.
Furthermore, the transmission way and the distribution state of the sound
produced by
the loudspeaker depend on the frequency of the loudspeaker. For example, the
low tone of sound
itself has no direction. When it sounds, it is slowly propagated to all
directions. Therefore, the
furnishing place for the super low tone is not so demanding as the common
loudspeaker while the
propagation way of the high tone of sound is similar to laser rays whose
proceeding direction is
almost straight, so that surfaces resulting in reflection should be prevented
for the furnishing
direction of the high tone body from the counteraction of tone quality and the
destruction of the
sound field. In other words, the sound pressure is the same in all of the
propagation directions
when the loudspeaker sounds. However, the front direction of the loudspeaker
must face the
continual double impact of the sound pressure and the high tone. Thus, a
strong feeling and an
obvious vibration are produced when we are hearing the Rock & Roll of the
heavy metal music or
fast rhythm music.
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The loudspeaker makes use of the vibration to propagate the converted sound or
music
signal to a space to form a sound field. So, we have a strong vibration
feeling when we get a
strong sound pressure in a sound field; we don't have a strong feeling when we
are in a slight
sound pressure. However, we are still within the vibration range of the sound
field. So, we receive
impact vibrations of the sound pressure when we are in the sound field, no
matter which music or
sound is played, even the small loudspeaker installed in the earphone has its
own sound field
range. The difference only lies in the different intensity.
The conventional earphone has two types. One is the earplug type and the other
is
earmuff type. Whichever earphone is used, its loudspeaker is placed near the
outer opening of the
external auditory canal while the right side of the loudspeaker is opposite to
the tympanic
membrane inside the external auditory canal of the ear so as to enable the ear
to directly receive
sound or music from the loudspeaker. Though an excellent tone quality is able
to be received by
the ear through this way due to the fact that the ear is within the sound
field range of the
loudspeaker and the sound pressure is vibrating between the loudspeaker and
ear membrane.
Moreover, the sound pressure from the earphone is about l OdB higher than that
from the common
loudspeaker with respect to the same sound received by the ear. In addition,
the sound pressure
generated by the earphone of the Walkman is always over 90dB; therefore the
conductive function
loss of the middle ear or the hearing loss is easily caused by such strong
sound pressure and the
unceasing impact noise.
Summary of the Invention
The applicant is a licensed doctor having clinic experiences for years. Since
patients
with hearing loss seeking medical counsel are more and more young people and
the applicant
found that the reason for that lies in the use of the Walkman resulting in the
damage of conductive
function in the middle ear. Besides, the impulse noise is the main reason for
the damage of the
tympanic membrane and the auditory ossicles.
Accordingly, it is a main object of the present invention to provide an
earphone by
which the splendid music is able to be heard as by the conventional earphone
and the conductive
function of middle ear is protected against damage resulting from impulse
noise.
It is another object of the present invention to provide an earphone without
impulse
noise for protection against conductive hearing loss, in which both the sound
emitted by the
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loudspeaker in the earphone and the sound outsides can be caught by the ear,
so that any events
outside can be realized at once without taking offthe earphone.
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Brief Description of the Drawings
Fig. 1 is a cross-sectional view of the human ear.
Fig. 2 is an assembly view of the malleus, the incus, and stapes of the middle
ear.
Fig. 3 is a perspective view of the external ear.
Fig. 4 is a perspective view of the present invention hanged between the
tragus and antitragus.
Fig. 5 is an elevation view of an earphone according to a preferred embodiment
of the present
invention.
Fig. 6 is a partially sectional view of the earphone according to the above
preferred embodiment of
the present invention.
F ig. 7 is a cross-sectional view of the housing of an earphone according to a
second preferred
embodiment of the present invention.
Figs. 8A to 8C are the front, rear and side views of the earplug mounting ring
according to the
above second embodiment of the present invention.
Fig. 9 is a schematic view of the earphone connected with the earplug mounting
ring according to
1 S :he above second embodiment of the present invention.
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Detailed Description of the Preferred Embodiments
Referring to Figs. 4 to 6, an earphone without impulse noise for protection
against
conductive hearing loss in accordance with a first preferred embodiment of the
present invention
comprises an earphone housing 40, a loudspeaker 50 mounted inside the earphone
housing 40, and
a conductive cord 60 connected to the loudspeaker 50.
A front portion of the earphone housing 40 provides an earplug 41 adapted to
be hanged
between the tragus 16 and the antitragus 15 of the external ear 10. A rear
portion of the earphone
housing 40 has a hood 42, which defines a hollow sound chamber 43 therein. The
conductive cord
60 is connected at a bottom end of the earphone housing 40 for transmitting
electric current to the
loudspeaker 50. A plurality of sound holes 44 are spacedly distributed on the
hood 42 to enable
the outside sound entering the earphone housing 40 therethrough.
The loudspeaker 50 is supported in the hollow sound chamber 43 of the hood 42.
The
loudspeaker 50 has a sound output end facing to the hood 42, i.e. rear portion
of the earphone
housing 40, while another back end of the loudspeaker 50 facing to the earplug
41 of the earphone
housing 40. In other words, the sound output end of the loudspeaker 50 must be
arranged opposite
to the back of the earplug of the earphone housing 40.
As mentioned above, the earphone housing 40 is worn on the user's ear by
handing the
earplug 41 between the tragus 16 and the antitragus I 5 of the external ear
10, wherein the hood 42
of the earphone housing 40 is exposed outside the external auditory canal 17.
In view of above, it
is realized that when the loudspeaker 50 inside the earphone housing 40 emits
sound through the
sound holes 44 against the antitragus 15, the sound pressure is absorbed and
rebounded by the
antitragus 15, so that the whole ear is situated in the range of the sound
field of the loudspeaker
50. Accordingly, the tone quality received from the earphone of the present
invention is the same
as from the conventional earphone; however, the sound pressure does not
directly impact upon the
tympanic membrane 171 of the external auditory canal 17 while the instant
impulse noise emitted
in the process of playing music can be avoided, so that the conductive
function of the middle ear
20 won't be damaged to influence the conductive hearing.
Fig. 7 illustrates a second preferred embodiment of an earphone without
impulse noise
for protection against conductive hearing loss in accordance with the present
invention, which also
comprises an earphone housing 70 and a loudspeaker 50 installed therein. A
front portion of the
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earphone housing 70 is arranged to be hanged between the tragus 16 and the
antitragus 15 of the
ear and attached on the coneha 14. The earphone housing 70 has a hollow sound
chamber 71
therein for receiving and holding the loudspeaker 50. A plurality of sound
holes 72 are distributed
on the surface around the front portion of the earphone housing and a
conductive cord 60 is
connected at the bottom end for transmitting electric current to the
loudspeaker 50. The
loudspeaker 50 also has a sound output end arranged facing to a back end of
the earphone housing.
As shown in Fig. 7 of the second preferred embodiment, when the loudspeaker 50
in the
earphone housing 70 sounds, the sound pressure is emitted towards the back
wall of the earphone
housing 70 and rebounded by the inner wall of the back end of the earphone
housing 70, so that
the whole ear is situated within the sound field of the loudspeaker 50.
Therefore, the tone quality
received is the same to by the conventional earphone; however, the sound
pressure won't have
direct impact upon the tympanic membrane l7l of the external auditory canal 17
while the instant
impulse noise emitted in the process of playing music can be avoided, so that
the conductive
function of the middle ear 20 won't be damaged to influence the conductive
hearing.
As shown in Fig. 8 and 9, a third preferred embodiment of the present
invention is
illustrated, which is an alternative mode of the above first preferred
embodiment that the earplug
--' l in the first embodiment is constructed as an independent component in
this third embodiment,
wherein an earplug body 80 is installed at a bottom end of the earphone
housing 40. The earplug
Body 80 provides a plug hook 81 extending downwardly from an upper portion
thereof adapted to
be hanged between the tragus l 6 and the antitragus 15, and a ring seat 82
connected to a lower end
:hereof for mounting the earplug body 80 to a rear end of the earphone housing
40. Also, the
earphone housing 40 can adjust its position upwards or downwards with respect
to the ring seat 82
in order to fit the ear size of the user.
Concluded from the above, the present invention includes the following
advantages:
1. With respect to sound with the same frequency, the sound pressure on the
human ear
can be reduced to the lowest extent while the same tone quality to that of the
conventional earphone is achievable.
2. The external auditory canal of the human ear can be protected against the
collision
of the impact noise so that the damage of the transmission function in the
middle ear
can thus be avoided. Therefore, a conductive hearing loss won't happen to the
people
loving to wear earphone for a long period.
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3. By using the present invention, both the sound emitted by the loudspeaker
in the
earphone and the sound outsides can be caught by the ear so that any events
outside
are able to be realized at once to take any proper action.
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