U.S. patent application number 09/066395 was filed with the patent office on 2001-08-16 for pick-up head for an electronic stethoscope.
Invention is credited to ORTEN, BIRGER.
Application Number | 20010014162 09/066395 |
Document ID | / |
Family ID | 19898767 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010014162 |
Kind Code |
A1 |
ORTEN, BIRGER |
August 16, 2001 |
PICK-UP HEAD FOR AN ELECTRONIC STETHOSCOPE
Abstract
The pick-up head (1) with an acousto-electrical transducer (4)
for converting sound vibrations to electrical signals, comprises as
characterizing features a sound influencing bell (2) arranged
around a slender peg (3) bonded directly to the transducer (4), and
the sound influencing bell (2) delimits a listening area on a body
surface and influences to a predetermined degree and in a
predetermined manner, by means of internal reflection and/or
absorption, the direct sound picked up by the slender center peg
(3). The bell (2) is acoustically decoupled from the center peg
(3).
Inventors: |
ORTEN, BIRGER; (ALESUND,
NO) |
Correspondence
Address: |
JOHN J CHRYSTAL
LADAS & PARRY
224 SOUTH MICHIGAN AVENUE
CHICAGO
IL
60604
|
Family ID: |
19898767 |
Appl. No.: |
09/066395 |
Filed: |
May 8, 1998 |
PCT Filed: |
November 14, 1996 |
PCT NO: |
PCT/NO96/00268 |
Current U.S.
Class: |
381/67 ;
600/528 |
Current CPC
Class: |
A61B 7/04 20130101 |
Class at
Publication: |
381/67 ;
600/528 |
International
Class: |
A61B 007/04; A61B
005/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 16, 1995 |
NO |
95 4636 |
Claims
1. A pick-up head for an electronic stethoscope, comprising at
least one acousto-electrical transducer (4) for providing at least
one electrical signal representing acoustical vibrations, and at
least one mechanical member (3) coupled to said transducer (4) for
conveying said acoustical vibrations from a body surface to said
transducer (4), characterized in that a sound influencing bell (2)
which is acoustically decoupled from said at least one mechanical
member (3), is arranged therearound for providing with an edge (7)
a delimited listening area on said body surface and for providing
with its inside wall(s) (8) a sound-influencing cavity surface
surrounding said at least one mechanical member (3) and being
adapted to reflect sound toward said at least one mechanical member
(3) with wall shape, i.e. angles and radii of curvature, as well as
surface material being predetermined parameters regarding conveying
and possibly emphasizing certain sound frequencies, and that said
at least one mechanical member is constituted by a straight,
slender peg (3) which is adapted to pick up frontally acoustical
vibrations from said body surface through a peg front area that is
a substantially smaller area than said delimited listening area,
and laterally possible reflected acoustical vibrations from said
cavity surface.
2. The pick-up head of claim 1, characterized in that a number of
slender pegs for picking up acoustical vibrations, are coupled to
one single acousto-electrical transducer (4).
3. The pick-up head of claim 1, characterized in that a number of
slender pegs for picking up acoustical vibrations, are coupled to
respective ones of a corresponding number of acousto-electrical
transducers for providing a corresponding number of separate
electrical signals.
4. The pick-up head of claim 1, 2 or 3, characterized in that the
edge (7) of said sound influencing bell is substantially flat and
has a circular, oval. square or multi-sided shape.
5. The pick-up head of one of claims 1-4, characterized in that at
least an area of the wall(s) (8) is adapted to absorb sound within
a predetermined frequency range.
6. The pick-up head of any one of the previous claims,
characterized in that a diaphragm (9) is fastened along the edge
(7) of said sound influencing bell to engage the body surface
directly, i.e. between said at least one peg (3) and said body
surface.
7. The pick-up head of any one of the previous claims,
characterized in that electronic circuitry (16) for processing the
electrical signals is included in a unit (18) which is integrated
with said pick-up head (1) or is fixed thereto possibly also with a
radio transmitter unit (17) for further communication with a
central unit which may comprise a computer.
Description
[0001] The present invention relates to electronic stethoscopes,
and more particularly a pick-up head for an electronic
stethoscope.
[0002] Stethoscopes are utilized within the industry, specially
when listening for certain sounds which may indicate defects in
machines, but are primarily used in the field of medicine for
listening to sounds in connection with special body functions. Of
particular interest are sounds in connection with important organs
like lungs, heart and veins.
[0003] A doctor will often listen for particular sounds among a
plurality of sounds received simultaneously. The various sounds
often correspond to special frequency bands, and in this connection
it is referred to the appended FIG. 4 which shows sound frequency
bands attached to special types of heart diseases. For example, a
doctor who is interested in a symptom of the type mitral stenosis,
achieves a substantial improvement if frequencies above about 80 Hz
can be removed, since sounds having frequencies above 80 Hz in
general can be attached to other phenomena than this type of heart
constriction.
[0004] Various techniques can be utilized for processing the sound
frequency ranges desired to be transmitted from the body to the
doctor's ear or to a sound recording apparatus. E.g. in the present
applicant's own Norwegian patent application no. 95.0495 there is
disclosed an electronic apparatus having an adjustable bandpass
filter for removing undesired frequencies, i.e. removing "noise" so
as to transmit only sounds of interest for the particular diagnosis
in question. However, it is also possible to attack the problem of
frequency-shaping and adaptation of sound frequencies already in
the microphone itself, or in the pick-up part of the stethoscope.
Ordinary stethoscopes without electronic amplification have already
been provided with special pick-up head designs for achieving
attenuation/amplification of different frequency bands, e.g. GB
2,051,584 A and U.S. Pat. No. 4,903,794, both of which disclose
stethoscope pick-up heads having special chambers designed to
provide resonance at certain frequencies. In both these
publications, the sound pick-up head has a forward diaphragm shaped
with a centrally situated, forward protruding tip for direct
engagement against a body surface.
[0005] Stethoscopes of the electronic type, i.e. having
acousto-electrical transducers, and of a type somewhat related to
the present invention as to design, are previously known from DE
2,703,781, DE 2,453,926 and DE 932,268. DE 2,703,781 discloses a
body sound pick-up device having a piezoelectric member. For
transmission of vibrations to this member, there is arranged a
central and protruding pin in a cylindrical opening. The purpose is
to avoid receiving of sound via the air. No measure for shaping the
frequency of picked up sound, can be found.
[0006] DE 2,453,926 shows an electronic stethoscope wherein the
sound pick-up member has a forward diaphragm having a centrally
situated, forward protruding "scull cap". However, sound vibrations
are transmitted further through an air space inside the diaphragm
to an inside mounted microphone member. Special features for
emphasizing/attenuating certain frequency bands are not
mentioned.
[0007] DE 932,268 discloses a microphone for picking up body
sounds, where a center peg transmits vibrations from a body surface
to an acousto-electrical converter via a quasi-rigid mechanical
connection. The center peg is surrounded by a forward projecting
circular edge which has as its purpose to provide an approximately
constant engagement force for the center peg against the skin. No
means can be found for influencing the transmitted sound regarding
removal of undesired sounds and undesired frequencies.
[0008] The object of the present invention is to provide a sound
pick-up head for use as a part of an electronic stethoscope, where
particularly interesting frequency ranges for special diagnosis
purposes are emphasized by means of the pick-up head construction
itself, at the sacrifice of other frequency ranges.
[0009] In accordance with the invention, the object is achieved by
providing a sound pick-up head of the type which is defined
precisely in the appended patent claims. Thus, the central feature
of the invention is that at least one slender peg for conveying
vibrations is arranged centrally inside a sound-affecting bell
which delimits with its edge a reflection and/or absorption space
surrounding the slender peg, in such a manner that certain
frequencies are reflected in toward the peg, and other frequencies
are prevented from such reflection, whereby the peg conveys
frequency-shaped sound. The bell itself is acoustically decoupled
from the slender peg, which in itself picks up sound only from a
very small area of the body surface, while sound supplied to the
peg secondarily after reflection inside the bell, in principle
originates from the larger, bounded body surface area under the
bell.
[0010] In the following the invention will be explained in closer
detail by means of embodiment examples, and it is at the same time
referred to the appended drawings, in which
[0011] FIG. 1 shows an embodiment of a pick-up head in accordance
with the invention,
[0012] FIG. 2 shows a pick-up head of the type shown in FIG. 1,
mounted together with an electronics part to constitute a complete
electronic stethoscope,
[0013] FIG. 3 shows a complete stethoscope of the same general type
as in FIG. 2, however with a different design of the pick-up head
reflector bell,
[0014] FIG. 4 is a frequency diagram indicating effective sound
frequency ranges for certain heart diseases, and
[0015] FIG. 5 shows conventionally recorded phono-cardiographic
curves.
[0016] In FIG. 1 is shown a basic embodiment of the pick-up head of
the invention. The pick-up head itself is shown with reference
numeral 1, and it comprises as its most important elements a sound
influencing bell 2, a center peg 3 and an acousto-electrical
transducer means 4. The peg 3 is bonded directly to the transducer
4, which is adapted to provide connection to electronic amplifying
and processing circuitry which is not shown in the figure, via
electrical contact points 5. The sound influencing bell 2 is
acoustically decoupled from the transducer 4 by means of a
vibration absorbing lining 6.
[0017] The figure should be perceived as a section through the
pick-up head 1, and an obvious pick-up head shape is that it is
circular symmetrical about a center axis which coincides with the
longitudinal axis of the center peg. However, the shape may also be
oval, or possibly such that the bell 2 has a square circumference,
or for that matter a triangular or multi-sided circumference.
[0018] The sound influencing bell 2 of the pick-up head delimits
the listening area on a body surface when the edge area 7 engages
the surface. Sound emanating from the delimited listening area on
the body surface can then be reflected against the inside wall 8 in
the sound influencing bell 2 and toward the center peg 3 to provide
extra sound in addition to the sound picked up directly by the peg
from a very small central area engaged by the peg. Important
parameters in this connection are the shape of the inside wall,
i.e. the possible curvature or flatness thereof, the slant angle B
between the inside wall 8 and the plane of the edge area 7, and
further the material of the inside wall 8 and the sound frequencies
present. A doubly-curved inside wall 8, e.g. with a parabolic
curvature in the cross section, will provide a focusing effect in
toward a certain position on the center peg 3, while a conical
inside wall 8 as shown in FIG. 1 (that is when the figure shows a
cross section through a circular symmetrical pick-up head), will
spread reflected sound more toward the full extent of the peg.
Thus, the different shapes of the inside wall 8 will be of
importance regarding arrival times to the transducer 4 for
different parts of the total sound signal from the delimited area
of the body surface, and it is possible to "tailor" the shape of
the inside wall 8 to provide the best possible response for the
pick-up head in relation to particularly interesting body sounds.
Of course, also an embodiment (not shown) of the invention will be
to provide a pick-up head inside wall 8 with a changeable shape,
preferably in such manner that one single, finger-operated button
on the outside of the pick-up head gives a change of shape by
direct mechanical transmission to a tightening member which forces
the inside wall 8 to change its curvature, and thereby also
provides a different total response for the pick-up head.
[0019] It is also possible to give an area or certain areas of the
inside wall 8 different sound-reflecting or sound-absorbing
properties, also depending on frequency, in order to influence the
pick-up head response in a desired direction regarding a favourable
transmission of special sounds. In one variant of the invention,
the sound influencing bell is equipped with a purely absorbing
inside wall. This will make it possible to remove echoes and
acoustics from the bell, and only the center peg will then pass on
sound vibrations to the transducer 4.
[0020] Among further variable parameters of the pick-up head 1, the
center peg 3 itself must be mentioned, which center peg as a
starting point is a stiff and elongate rod of a hard material, e.g.
steel. However, the pick-up head may be equipped with a number of
such pegs, centrally arranged inside the sound influencing bell 2.
The pegs may then be connected to one single acousto-electrical
transducer means 4, or separate transducers may be arranged for
each respective peg, in order to obtain double, triple, etc. sound
pickup. In such "multipeg" cases, the peg angles may deviate from a
precise axial direction (relative to the shown one-peg case of FIG.
1), and the direction to and the depth of sound sources inside the
body surface can then possibly be calculated by means of attached
electronic circuitry and computer equipment.
[0021] While underlining that the gist of the present invention is
the special combination of direct sound from a small central area,
provided by means of a (or a number on slender center peg(s), and
reflected sound from the larger, delimited body surface area via
the inside of the sound influencing bell and to the center peg,
with a "purpose-adapted" size and shape of the bell inside wall 8,
one particular, further embodiment should be noted: It is possible
to change the properties of the pick-up head beyond what has been
mentioned above, by tautening a diaphragm 9, shown in FIG. 1 as a
broken line, over the entire opening of the sound influencing bell,
i.e. outside the forward protruding center peg 3. A fastening means
10 for the diaphragm 9 must then be provided around the outer edge
of the bell. The effect of such a diaphragm is that the center peg,
which then engages the diaphragm, will catch sounds from a larger
area, however this solution will also give more contact noise from
the body surface area of interest, and will normally not be a
preferred solution.
[0022] In FIG. 1, the pick-up head is equipped on top with a socket
11. In the embodiments appearing from FIGS. 2 and 3, it appears
that the socket 11 is used to provide complete stethoscopes 12, 13
with a shape approximately like a flashlight, where an elongate
main body 18 contains complete amplifying and processing circuitry
in an electronics part 16, connected to the transducer means 4 via
the contact points 5 (see. FIG. 1). Reference numeral 17 indicates
schematically an antenna of the radio type, optionally for
transmitting modulated light, or for transmitting ultrasound, and
in any case for transmitting information-carrying radiation which
is received by a stationary (not shown) receiver apparatus. Of
course a wire connection is also possible, but then the hand-held
unit 12, 13 may actually be reduced to merely unit 1, with wires
from the contact points 5 to a more complete, stationary signal
processing unit, the pick-up head 1 itself then constituting the
hand-held unit.
[0023] In FIG. 2 the pick-up head 1 is of substantially the same
type as shown in FIG. 1, while in FIG. 3 is shown a doubly-curved
inside wall 15 in the sound influencing bell 2. The edge area of
the bell is in this case shaped more sharply as an edge 14.
[0024] FIG. 4 shows a diagram regarding the location within the
audible range of special sounds attached to particular heart
disease symptoms. It is to be noted, in comparison with the audible
range (20 Hz-20 kHz) and the range of typical respiratory sounds
(200-700 Hz), that respectively mitral stenosis has typical
frequencies in the range 25-80 Hz, the first and second heart
sounds occur with frequencies in the range 20-140 Hz, the atrial
septal defect in the range 20-70 Hz, aortic and mitral
regurgitation provides sounds having frequencies in the range
170-900 Hz, and ejection murmurs are typically situated at 130-500
Hz. The pickup head in accordance with the invention can be used
just to accentuate such special frequency ranges, or to suppress
the transmission of outside frequencies, if this is the more
desirable view.
[0025] It is to be noted that the pick-up head in accordance with
the invention turns out to provide good results also when listening
on the outside of clothes.
[0026] In use, the sound influencing bell forms a closed space
around the center peg, and hence has the effect that sounds coming
from the outside area, will not be picked up by the peg. Thus, the
bell also functions as a shield against other signals than "usable
signals". Only body sounds picked up inside the bell shall be
valid, and undesired signals shall be removed.
[0027] It has previously been stated that different shapes of a
reflecting inside wall in the sound influencing bell will provide
reflections that can be directed substantially toward one position
on the center peg, or in a more spread-out fashion toward various
positions. Thus, the shape of the inside wall can be adapted to
compensate for different arrival times for different sounds,
whereby certain arrivals can be suppressed and other arrivals can
be emphasized. Arrival time as a consequence of the geometrical
shape and the choice of material of the sound influencing bell, is
an important parameter. The fact that the bell provides reflections
scattered toward different positions at different times, will give
a phase shift in time/sound. See e.g. the curve portions shown in
FIG. 5, recorded using traditional phono-cardiography. Such curves
may to a certain degree be rendered sharper, better defined and
simpler to interpret by means of the emphasis and accentuation
which can be achieved by the pick-up head in accordance with the
invention.
* * * * *