Note: Descriptions are shown in the official language in which they were submitted.
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PLAB:025
PQST-AURICLE CONTOURED HEADSET FOR TWO-WAY
VOICE COMMUNICATION
This invention relates to headsets for two-way
voice communication, such as might be used by telephone
operators, aircraft pilots, air-traffic controllers, etc.,
and to post-auricle headset capsules for such headsets.
It has long been known that headsets for two-way
voice communication can advantageously be constructed
from small, lightweight components7 such that the overall
weight of the headset may be on the order of one ounce.
For example, V.S. Patent 3,184,556, issued May 18, 1965~
to W. K. Larkin~ discloses a miniaturized headset wherein
a hearing-aid size microphone transdu~er and a similarly
miniaturi~ed receiver transducer are placed in a capsule
mounted near the user's ear; speech is conducted to the
microphone via an acoustic tube positioned near the user's
mouth~ while incoming communications emanating from the
receiver are conducted to the user's ear via a second
acou5tic tube. Larkin-type headsets have been used with
either a light headband or the temple bar of an eyeglass
frame as the supporting member for the transducer housing.
In order to eliminate the necessity for having a
headband or an eyeg1ass frame to support the transducer
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housing, various headsets have employed the so-called
"post-auricle" corfiguration, wherein the transducers are
placed in a capsule which is mounted behind ~he ear of the
user, and is shaped to fit generally along the saddle area
behind the ear. For example, U.S. Patent 3,54~,118, issued
December 15, 1970, to K. J. ~utchings, discloses such a
post-auricle arrangement, with an acoustic voice tube pass-
ing over the ear and into the headset capsule, and an
acoustic ear tube passing from the capsule under the
wearer's ear and up into the ear canal. ~he arrangement
disclosed in the Hutchings patent is embodied in a headset
commercially sold by Plantronics, Inc., the assignee of
the present application, under its trademark "StarSet."
It has also been known to provide a headset having
a capsule shape generally similar to that disclosed in the
above-identified Hutchings patent, but not employing an
acoustic voice tube. Instead, an electret-type microphone
is mounted at the end of a swivelable boom, so that it can
be positioned near the wearer's mouth~ The boom is hollow,
and electrical lead wires are passed from the electret
microphone through the boom and into the headset capsule,
where they are incorporated into the main headset cable~
which in turn is plugged into a switchboard or other means
of connection to a telephone line. An example of this
boom-electret microphone arrangement is found in the
headset commercially offered by Northern Electric Company
under its trademark "~enture."
3~ The aforementioned headset designs, and all other
post-auricle headset designs known to applicants, have
attempted to provide stability by means of the judicious
location o the acoustic voice tube or boom; or by means
of the ancho~ing effect of the acoustic ear tube; or by
~5 attempting to make the saddie curvature of the headset
capsule fit as many human ears as possible. Until the
present invention, shaping of other portions of the
headset capsule was limited to efforts to contain the
transducers adequately, and to make the top-most portion
of the capsule as thin as possible, thereby to provide
ade~uate mounting space for the headset to pass over the
top of the ear, where the distance between the auricle
and the skull is usually small, especially if the user
is wearing eyeglasses.
Headset design is primarily a subjective human
engineering problem, with very few workable theoretical
guide lines. Proposed designs generally need to be tried
out on many different people of varying heights, weight,
ages, head shapes, etc., to determine their reactions with
regard to comfort, stability, and acoustic properties.
SUMMARY OF THE INVENTION
Applicants have found that a substantial enhancement
to stability of a post-auricle headset is obtained by
certain contouring of the side surfaces of the headset
capsule. Strictly speaking, it is necessary to shape only
one side of the capsule, but for purposes of versatility,
it is desirable to shape both sides, so that the headset
can conveniently be worn on either side o~ the head.
One advantageous type of capsule contouring has been
found by applicants to be related to the bony protrusion
of the skull known as the mastoid process. Headset
stability is enhanced by tapering the lower portion of the
capsule sidesr so that the capsule rests on the mastoid
process, thereby minimi~ing pressure points and more
widely distributing the weight of the capsule and the
slight pull of the line cable. In addition, to providing
greater stability, this shaping results in a capsule of a given
weight feeling lighter to the ~Iser, and being more comfortakle
to wear for long periods.
Another advantageous type of headset capsule shaping has
been found to be the provision of some concavity at the top o~
the capsule, so as to approximately shape the capsule to the
curvature of the skull. Fitting the capsule to the skull
enhances stability by providing a greater contact surface
between the headset and the wearer's head.
Comfort and stability are especially enhanced by the
incorporation of both of the above contouring features into the
capsule design.
The headset includes a microphone for converting the
wearer's speech to electrical signals. The preferred microphone
is an electret microphone. Acoustic tube assemblies conduct
sound from near the wearer's mouth to th~ electret microphone
and from a magnetic receiver to the wearer's ear.
BRIEF DESCRI~TION OF THE DRAWINGS
The invention may be better understood by reference to the
~0 drawings, in which:
FIG. 1 is a pictorial view of a headset according to the
present invention.
FIG. 2 is a rear view of a headset capsule according to the
present invention, showing the tapering of the capsule to fit
over and rest upon the mastoid process.
FIG. 3 is a view of the post-auricle area of a typical
human head, showing the mastoid process.
FIG. 4 is a top view of a headset capsule according
to the present invention, showing outward concavity of
the side portions, to conform to the curvature of the
skull, appearing with FIGS. l and 2.
s
FIG. 5 is a contour drawing, showing the preferred
dimensions for shaping a headset capsule according to the
present invention.
FIG. 6 is an illustration of the post-auricle head-
set capsule according to the present invention, and
including an electret microphone.
FIG. 7 is a cross-sectional view of an alternative
post-auricle headset capsule configuration including an
electret microphone.
DESCRIPTION OF THE PREFERRED EMBODI~ENTS
Referring now to FIG. 1 of the drawings, a headset
is shown, including a post-auricle capsule 1. The cap-
sule contains a receiver transducer for recep~ion of
electrical signals via wires in cable 4 and conversion
of these signals to sound by a receiver transducer.
The receiver~s sound signals are conveyed ~y acoustic
tube 3 to the wearer's ear canal. The headset capsule
1 may also contain a microphone transducer for convert-
ing voice signals to electrical signals, which are then
conveyed by means of wires in cable 4 to a suitable
amplification device, and thence onto a telephone line~
or other communication link. Voice signals are conveyed
to the microphone transducer via acoustic tube 2~ which
is swivelably postioned near the wearer's mouth.
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Alternatively, in the boom microphone arrangement
described above, the microphone transducer migl1t be
located at the end of tube 2~ which would then not Eunc-
tion as an acoustic tube, but rather as a condui. tube for
one or more lead wires from the boom microphone into the
headset capsule. The tube might itself function as a lead
or as a ground return, it made of conductive metal. The
capsule 1 includes a removable cover portion 14, to
facilitate repair work on the headset if required.
As shown in FIG~. 2 and 4 of the drawings, the head-
set capsule is comprised of two mating halves 5 and 6.
When viewed from the rear, as in FIG 2, it is seen that
the sides of the headset capsule are not plane, but are
contoured. Contoured portions 7 and 8 are designed to
make the capsule narrower toward the bottom. This con-
touring of the lower side surfaces of the capsule is done
to take account of the shape of the human skull in the
area behind the ear. More`particularly, as shown in FIG.
3, there is a bony protrusion behind the ear known as the
mastoid process, shown at 11. In the present invention,
it has been found that better fit, comfort and stability
are obtained if the sides of the headset are contoured to
fit over the mastoid process 11. Of course, the capsule
must also have a curved portion ~o fit the saddle area 10
behind the auricle 9, as known in the prior art.
Another aspect of capsule shaping according to the
present invention is to contour the upper side portions of
3~ headset capsule 1 to the curvature of the s~ull in a fore-
and-aft direction. As illustrated in FIG. ~, this curva-
ture of the upper side portions is shown, viewed above, by
the outwardly concave surfaces 12 and 13. This curvature
is exaggerated in FIG. 4 for clarity; in actuality, the
curvature of the head in the area near the top of the ear
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is somewhat less than as shown in FIG. ~. It has been
found that wearer comfort and stability are further
enhanced by shaping the capsule to this curvature of the
head.
Referring now to FIG. 5 of the drawings, a contour
drawing of a headset capsule according to the present
invention is shown. The dimensions shown are in mils,
measured from the line dividing the left and right halves
of the capsule (see Figs. 2 and 4). The contouring to fit
the mastoid process is shown in FIG. 5 by the area wherein
the thickness of a capsule half decreases from ~50 mils to
~00 mils. Although it would be possible to broaden the
lower portion of the capsule once it has passed below the
mastoid process, and still be within the scope of the
present invention, it is preferable not to do so, because
of the variable length and location of the mastoid process
among various prospective wearers.
During use, the headset is partially supported on the
mastoid process, thereby dividing and distributing the
weight of the capsule and the slight pull of the headset
cable 4 between the mastoid process 11 (FIG. 3) and the
saddle area 10 of the ear.
Referring now to FIG. 6 of the drawings, when the
microphone of the headset is to be located in the headset
capsule, it is advan~ayeous to use a microphone of the
electret type. An electret microphone operates on the
principle of converting sound into changes of electrical
field between a metallic diaphragm and a metal back plate,
which operate together as a capacitor. FIG. 6 shows a
typical arrangement of such a headset, in which an elec-
tret microphone 15 is seated in a capsule half 6 by means
3S of ribs 16, which may be molded integrally with the
capsule-half 6. Sound is conducted to the electret
microphone 15 by way of a tube 17, which may be of stain-
less steel. Tube 17 is surrounded by a wire retainer 18
welded to tube 17 where it enters the capsule. Tube 17 is
press-fitted to an elastomeric coupler 19, the other end
of which is press-fitted onto the electret microphone 15.
Lead wires 20 are provided to connect electret microphone
15 to wires of the headset cable 4. A suitable voice tube
arrangement, not shown, may be employed to pick up sound
1~ near the wearer's mouth and convey it into tube 17, thus
comprising an acoustic voice tube assembly.
A magnetic or dynamic receiver 21 is fitted in a
rubber boot 22, which in turn is placed in the headset
capsule half, in the space formed between ribs 23. Leads
24 are employed to conduct electrical signals from wires
in the headset cable 4 to the receiver 21. An elastomeric
coupler 25 connects the receiver 21 to a metal receiver
insert 26, which passes through the capsule wall. An
acoustic ear tube, partially shown at 27, conducts sound
from the metal receiver insert 2b to the wearer's ear
canal, in conventional manner, thus constituting an
acoustic receiver tube assembly.
An alternative arrangement for mounting the electret
microphone in a headset capsule is shown in FIG. 7 of the
drawings. This arrangement is substantially similar to
that of FIG. 6, except that a first O-ring 28, of suitable
elastomeric material, is placed around the main casing of
electret microphone 15, to allow cushioning for the micro-
phone if the headset is subjected to jarring in either the
vertical direction or the transverse direc~ion. A second
O-ring 29 is pl~ced in front of the casing of electret
microphone 15~ to allow for lateral cushioning of the
microphone in case the headset is subjected to jarring in
the lateral direction.
In the arrangement of FIG. 7, sound is conducted to
the electret rl1icrcphone 15 by way of an acoustic tube 30,
which is surrounded by a third elastomeric O-ring 31 where
it enters the capsule. Acoustic tube 30 ends at passageway
32, through which sound is conducted to cavity 33, where
it is picked up by the electret microphone 15. A magnetic
or dynamic receiver 35 is mounted in the capsule 34 in a
manner si~ilar to that described for the arrangement of
FIG. 6. Sound is conducted from magnetic receiver 35 v~a
a receiver-insert 36 to an acoustic ear tube, not shown.
It should be understood that various alternatives to
the structures shown herein may be employed in practicing
the present invention. It is intended that the following
claims define the invention, and that structure within the
scope of these claims and their equivalents be covered
thereby.
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