U.S. patent application number 15/925168 was filed with the patent office on 2019-09-19 for stringed instrument resonance system.
The applicant listed for this patent is Fender Musical Instruments Corporation. Invention is credited to Joshua D. Hurst, Timothy P. Shaw, Brian C. Swerdfeger.
Application Number | 20190287497 15/925168 |
Document ID | / |
Family ID | 67905989 |
Filed Date | 2019-09-19 |
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United States Patent
Application |
20190287497 |
Kind Code |
A1 |
Shaw; Timothy P. ; et
al. |
September 19, 2019 |
STRINGED INSTRUMENT RESONANCE SYSTEM
Abstract
A stringed instrument, such as a semi-acoustic electric guitar,
can employ a resonance system that consists of a body having at
least one internal cavity accessed by a soundhole continuously
extending from a top cover. The soundhole may have a continuously
curvilinear transition from the top cover and a length
corresponding with an altered resonance frequency of the instrument
body.
Inventors: |
Shaw; Timothy P.;
(Hendersonville, TN) ; Hurst; Joshua D.;
(Nashville, TN) ; Swerdfeger; Brian C.; (Mission
Viejo, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Fender Musical Instruments Corporation |
Scottsdale |
AZ |
US |
|
|
Family ID: |
67905989 |
Appl. No.: |
15/925168 |
Filed: |
March 19, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G10D 3/02 20130101; G10D
1/085 20130101 |
International
Class: |
G10D 3/02 20060101
G10D003/02; G10D 1/08 20060101 G10D001/08 |
Claims
1. An apparatus comprising an instrument body having at least one
internal cavity accessed by a soundhole continuously extending from
a top cover, the soundhole disposed between and contacting a first
rail of a suspension and a second rail of the suspension, the
soundhole having a continuously curvilinear transition from the top
cover and a length corresponding with an altered resonance
frequency of the instrument body.
2. The apparatus of claim 1, wherein the instrument body is a
hollow body electric guitar body.
3. The apparatus of claim 1, wherein the top cover supports a
bridge and at least one electronic pickup.
4. The apparatus of claim 3, wherein a neck continuously extends
from the instrument body.
5. The apparatus of claim 4, wherein the soundhole is aligned with,
and disposed between, the neck and bridge directly below strings
extending from the bridge to a headstock portion of the neck.
6. The apparatus of claim 1, wherein the soundhole has a circular
shape in a plane parallel to the top cover.
7. The apparatus of claim 1, wherein the top cover is positioned in
a recess of the instrument body.
8. The apparatus of claim 1, wherein the soundhole length is at
least 1'' and no greater than 1.25''.
9. The apparatus of claim 1, wherein the altered resonance
frequency is 175 Hz.
10. A system comprising a body having a single internal cavity
accessed by a soundhole continuously extending from a top cover,
the soundhole contacting first and second rails of a suspension,
each rail extending parallel to the top cover, the soundhole having
a continuously curvilinear transition from the top cover and a
length corresponding with an altered resonance frequency of the
body.
11. The system of claim 10, wherein the soundhole is separated from
a floor of the single internal cavity by the suspension.
12. The system of claim 10, wherein the first and second rails
respectively attach to opposite sides of the soundhole.
13. The system of claim 10, wherein a bridge deck spans the first
and second rails to support a bridge affixed to the top cover.
14. The system of claim 10, wherein each rail attaches to the body
via a notch.
15. The system of claim 10, wherein the single internal cavity has
a volume of at least 150 cubic inches and no greater than 160 cubic
inches.
16. The system of claim 15, wherein the body has a thickness of no
greater than 1.75'', as measured perpendicular to the top
cover.
17. The system of claim 10, wherein the body has a resonance
frequency of greater than 175 Hz without the soundhole.
18. A method comprising: providing an instrument body having a
single internal cavity accessed by at least one soundhole
continuously extending from a top cover, the soundhole disposed
between and contacting first and second rails of a suspension, the
at least one soundhole having a continuously curvilinear transition
from the top cover and a length corresponding with a first altered
resonance frequency of the instrument body; and changing the
soundhole to produce a second altered resonance frequency of the
instrument body.
19. The method of claim 18, wherein the soundhole is changed by
positioning an insert into the soundhole, the insert having a
different acoustic profile than the soundhole that corresponds with
a higher second altered resonance frequency than the first altered
resonance frequency.
20. The method of claim 18, wherein the soundhole is changed by
blocking the soundhole that corresponds with a higher second
altered resonance frequency than the first altered resonance
frequency.
Description
SUMMARY
[0001] A resonance system, in accordance with assorted embodiments,
has an instrument body having at least one internal cavity accessed
by a soundhole continuously extending from a top cover. The
soundhole has a continuously curvilinear transition from the top
cover and a length corresponding with an altered resonance
frequency of the instrument body.
[0002] In other embodiments, a resonance system has a body having a
single internal cavity accessed by a soundhole continuously
extending from a top cover. The soundhole has a continuously
curvilinear transition from the top cover and a length
corresponding with an altered resonance frequency of the body.
[0003] A stringed instrument resonance system, in some embodiments,
is utilized by providing an instrument body having a single
internal cavity accessed by at least one soundhole continuously
extending from a top cover with the soundhole having a continuously
curvilinear transition from the top cover and a length
corresponding with a first altered resonance frequency of the
instrument body. The soundhole is changed to produce a second
altered resonance frequency of the instrument body.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 displays a block representation of an example
stringed instrument assembly that may be employed in accordance
with various embodiments.
[0005] FIGS. 2A & 2B respectively represent portions of an
example stringed instrument that may be employed by the stringed
instrument assembly of FIG. 1.
[0006] FIGS. 3A-3D respectively depict line representations of
portions of an example stringed instrument resonance system
configured in accordance with some embodiments.
[0007] FIG. 4 is a cross-sectional representation of a portion of
an example stringed instrument resonance system arranged in
accordance with various embodiments.
[0008] FIG. 5 conveys a cross-sectional representation of a portion
of an example stringed instrument resonance system utilized in
accordance with assorted embodiments.
[0009] FIG. 6 illustrates a line representation of portions of an
example stringed instrument resonance system that may be employed
in accordance with various embodiments.
[0010] FIG. 7 shows an example resonance optimization routine that
can be carried out with the assorted embodiments of FIGS. 1-6.
DETAILED DESCRIPTION
[0011] The present disclosure generally relates to a resonance
system for a stringed instrument that can optimize the acoustic
properties of an irregularly shaped instrument body.
[0012] A stringed instrument has been tied to a particular tonality
and resonant frequency range based on the size and shape of the
instrument's body. Instrument bodies with symmetric shapes,
relatively large internal volumes, and/or relatively light physical
bracing can have robust frequency ranges with clear tone. For
example, a violin, cello, and acoustic guitar each employ
relatively large internal volumes that are utilized to provide
smooth and clear reproduction of a range of different
frequencies.
[0013] While such stringed instruments can provide tonal quality,
acoustic amplitude and volume can be difficult unless the
instrument is played in a location with optimal acoustic
properties, such as a concert hall. The use of acoustic transducers
can allow sounds produced from a stringed instrument to be
amplified, manipulated, and recorded, but often with acoustic
degradation due to the limitations of the acoustic transducer and
the transducer location on the instrument.
[0014] In contrast to stringed instruments that are acoustic in
nature, an instrument can be configured to optimize acoustic
transducer placement and performance with respect to vibrating
strings. Such electric stringed instruments can accurately
reproduce relatively large frequency ranges and easily add signal
manipulations, such as tone and volume, when plugged into a signal
processor. However, an electric stringed instrument can have
limited acoustic properties due, at least in part, to priority
placement of acoustic transducer(s) and extensive physical bracing
that presents an irregularly shaped internal cavity with limited
volume.
[0015] Accordingly, various embodiments are directed to a resonance
system for a stringed instrument that optimizes frequency response
and tonality by changing at least one resonance frequency of the
instrument's body. By providing one or more soundholes that reverse
the acoustic phase of waves from the inside the instrument's body,
an electric stringed instrument can have improved acoustic depth,
quality, tonality, and amplitude when not connected to a signal
processor. The ability to tune a soundhole of an electric stringed
instrument allows a diverse variety of audible frequencies to be
optimized despite an irregular shaped internal instrument cavity
with relatively small volume.
[0016] FIG. 1 displays a block representation of an example
stringed instrument assembly 100 in which assorted embodiments of
the present disclosure can be practiced. The stringed instrument
assembly 100 can have any number of stringed instruments 102 that
are individually, and/or collectively connected to one or more
signal processors 104. As a non-limiting example, multiple
different stringed instruments 102, such as a six-string guitar and
a four-string bass, can each be connected to different signal
processors 104, such as a foot pedal, while each being connected to
a common signal processor 104, such as a sound board, amplifier, or
pre-amp, via one or more connections 106, such as a wired and/or
wireless signal pathway.
[0017] A stringed instrument 102 is not limited to a particular
size, shape, type, sound characterization, or material
construction, but can in some embodiments be guitar defined at
least by a body 108 affixed to a neck 110. One or more strings 112,
such as metal, nylon, or other acoustic material, can continuously
extend from a headstock 114 to a bridge 116 across the neck 110 and
portions of the body 108. Articulation of at least one string 112
produces a predetermined tone and frequency range that can be
enhanced by the body 108, signal processor 104, or both. For
instance, an acoustic guitar can have no electronic transducing
means and rely on the body 108 to reverberate sound generated by
the string(s) 112 while an electric guitar can have minimal
acoustic chamber in the body 108 and rely on one or more active or
passive electronic transducing means, such as a wound coil pickup,
humbucking pickup, and piezo pickup.
[0018] While an acoustic guitar can be outfitted with electronic
transducing means, the string vibration dynamics of a hollow body
108 are different than the solid body 108 often found on electric
guitars. Hence, a hollow body electric guitar, which may be
characterized as a semi-acoustic guitar, attempts to provide
conventional electric guitar string 112 dynamics with acoustic
(unplugged) tonality that more closely resembles acoustic guitar
sound properties. In yet, modifying an electric guitar to be more
similar to an acoustic guitar is much more difficult than modifying
an acoustic guitar to be more similar to an electric guitar due to
the interior cavity of the body 108 playing such a critical role in
producing rich, deep, and smooth acoustic tonality.
[0019] FIGS. 2A and 2B respectively provide line representations of
various portions of an example stringed instrument 120 in which
assorted embodiments can be employed. FIG. 2A displays a cut-away
perspective of a guitar body 108 and neck 110 without a top cover
122 where a bridge 116 is mounted. The body 108 can be any shape,
size, and material construction as part of an electric guitar, but
is considered a hollow body electric/semi-acoustic guitar with a
relatively thin profile, such as 1.75'' or less along the Z axis, a
relatively small internal cavity 124 volume, such as 200 cubic
inches or less, and internal features 126 for mounting electronics,
such as knobs, batteries, circuitry, and pickups.
[0020] It is noted that a solid body electric guitar would differ
from the body 108 of FIG. 2A by having no acoustically appreciable
internal cavity 124 that enhances the acoustic properties of the
vibrating strings 112. In contrast, an acoustic guitar would differ
from the body 108 of FIG. 2A by having a larger internal cavity 124
that has a shape conducive to enhancing the acoustic properties of
the vibrating strings 112. An acoustic guitar would additionally
have physical bracing within the cavity 124 to support a top cover
while an electric guitar has ample body structure without bracing
to support a top cover 122 and aggressive manipulation of the
strings 112.
[0021] FIG. 2B displays the stringed instrument 120 fully assembled
and ready to play music with the top cover 122 installed and
strings tuned to a predetermined tension across one or more pickups
128. To take advantage of the volume of air occupying the internal
cavity 124, one or more shaped ports, such as the c hole 130 and/or
f hole 132, can allow air to flow into, and out of, the body 108 to
enhance and alter the acoustic properties of the vibrating strings
112. That is, sound waves and air translating through the internal
cavity 124 from the strings 112 create harmonics at various
different frequencies that would otherwise not be produced by the
strings alone, but could be detected by a pickup 128 to allow for
signal manipulation and playback via one or more signal processors
104.
[0022] While the addition of internal cavities and one or more
sound ports 130/132 can provide some increased acoustic properties,
the irregular shape, as defined as a non-symmetric shape in the X-Y
plane, and internal features 126 degrades acoustic performance of
the instrument 120. Hence, there is a general interest in
optimizing the acoustic performance of stringed instruments with
irregular shaped internal cavities, particularly internal cavities
with volumes that are too small to provide resonance in the
internal cavity at lower frequencies, such as less than 500 Hz.
[0023] FIGS. 3A-3D respectively illustrate portions of an example
stringed instrument 140 that is configured in accordance with some
embodiments to provide optimized acoustic properties in a
semi-hollow/hollow body electric guitar. The top view of FIG. 3A
shows how the neck 110 extends from the body 108 and supports
strings 112, along with a bridge 116, over a soundhole 142 and
pickups 128. It is contemplated that the number, type, and location
of pickups 128 can be altered, without limitation or detriment to
the novel aspects of the present disclosure.
[0024] The shape and size of the instrument body 108, particularly
the thickness measured parallel to the Z axis, contributes to an
irregular shaped internal cavity 124, as shown by segmented region
144. It is noted that the body 108 has a non-limiting length 146 of
16.25'' and a non-limiting width 148 of 13.125'' at the widest
point that allow for a 154 cubic inch volume (+/-5%) of the
internal cavity 124. The irregular cavity shape 124 may
additionally be influenced by internal features, such as electronic
mounting lands and the presence of electronics, to be non-symmetric
in the X-Y plane about both the X axis (vertical symmetry) and
about the Y axis (horizontal symmetry). Despite the irregular
cavity shape, the soundhole 142 provides fluid access to the cavity
124 from directly under the strings 112, which mitigates loss of
acoustic waves between the strings 112 and the cavity 124.
[0025] The side profile view of FIG. 3B conveys how the internal
cavity is constrained by the relatively thin body 108. That is, a
body thickness 150 of less than 2'', such as 1.75'', prevents the
internal cavity 124 from being large enough to naturally resonate
frequencies in a low range, such as below 500 Hz. The side view of
FIG. 3B further conveys how the top cover 122 is a planar surface
parallel to the X-Y plane, which contrasts bowed, rounded, or other
curvilinear shapes that have depth along the Z axis. Such planar
top cover 122 stresses the ability of the body 108 and bridge 116
to control string vibrations to produce a musically pleasing sound.
Thus, the internal cavity 124 is tuned in some embodiments in
concert with the soundhole 142 to alter the resonance of the
internal cavity 124, and body 108, to optimize the acoustical
volume, bass response, and tonality of the instrument 140 when not
connected to a signal processor 104.
[0026] FIG. 3C has the instrument 140 with the top cover 122
removed to show the tuned internal cavity 124 in accordance with
assorted embodiments. The inner cavity 124 is configured as a
single, continuous chamber 152 with a floor 154 and sidewall 156
extending to maximize the volume of the inner cavity 124. It is
noted that a single chamber 152 is not required and any number of
physically separate chambers can be positioned in the body 108,
beneath the top cover 122. However, a single chamber arrangement
can allow for acoustic material(s) to be selectively inserted into
the body 108 to influence the acoustic properties of the instrument
140. For instance, one or more materials, such as polyester, other
acoustic fabrics, foam, elastomer, and rubber, can be inserted into
the chamber 152 to alter the practical volume of the chamber 152
and tune the instrument 140 to a lower, or higher, resonant
frequency range.
[0027] The perspective of FIG. 3C illustrates a single soundhole
142 is mounted in position above the chamber floor 154 by a
suspension 158 that is also partially separated from the floor 154
to promote efficient movement of air, and overall instrument
tonality, compared to if the suspension continuously extended to
the floor 154 and/or restricted airflow to, and from, the soundhole
142. The suspension 158 has a pair of rails 160 that are each
notched into the body 108 to support the soundhole 142 and a bridge
deck 162 where strings attach to the body/top cover.
[0028] The airflow within the chamber 152 can be tuned via the
structure of the floor 154 and sidewall 156 in a variety of
different ways, such as size, shape, and depth, which allows for a
diverse range of resonant frequencies for the instrument 140 and
frequency reproduction ranges with optimized acoustic properties.
In the non-limiting example of FIG. 3C, the floor 154 meets the
sidewall 156 with a continuously curvilinear shoulder 164 that
promotes laminar, as opposed to turbulent, airflow in response to
user articulation of strings of the instrument 140. The
configuration of single chamber 152 with a radiused shoulder 164,
as shown, can complement increased volumes of air being influence
by vibration of string(s) by mitigating flutter, the generation of
vacuum in the chamber 152, and eddys that can degrade the
transmission of sound waves and the acoustic quality of the
instrument 140.
[0029] It is contemplated that the suspension 158 can provide some
bracing of the top cover, but such bracing is minimal due to the
top cover seating into a recess 166 of the body 108. That is, the
size, strength, and position of the suspension 158 can be arranged
for optimal chamber 152 volume and acoustic properties instead of
being arranged for structural support for the top cover due to the
top cover having both lateral (in the X-Y plane) and vertical
(parallel to the Z axis) support provided by the recess 166. The
ability to tune the depth of the recess 166 allows for adjustment
of the amount of physical support for the top cover. As such, the
amount of flex allowed in the top cover during operation can be
tuned for user preference by adjusting the amount of surface area
of the top cover contacting the body 108 at the recess sidewall
168.
[0030] The cross-sectional view of the stringed instrument in FIG.
3D displays how the soundhole 142, suspension 158, and chamber 152
can be arranged relative to the top cover 122. As shown, the top
cover 122 continuously extends within the body recess 166 to
concurrently physically rest above the soundhole 142 and suspension
bridge deck 162 without extending above the edge 170 of the
instrument body 108 along the Z axis. The top cover 122 has a sound
aperture 172 with centerpoint that is aligned with the soundhole
142 centerpoint along the Z axis.
[0031] Although not required or limiting, various embodiments
configure the sound aperture 172 with a continuously curvilinear
rim 174 that matches the diameter and soundhole rim 176 at a
transition region where the top cover 122 meets the soundhole. By
shaping the sound aperture 172 to match the soundhole rim 176 with
a radiused surface, laminar airflow is promoted that increases the
quality of sound waves entering, and exiting, the soundhole 142. In
some embodiments, the soundhole 142 continuously extends to a
position even with, or above, the top cover 122 along the Z axis,
which would convert the curvilinear aperture rim 172 to a joint
where the top cover 122 meets the side of the soundhole 142. It is
noted that the soundhole 142 has an acoustic profile that
corresponds with the structural configuration of the soundhole
itself.
[0032] Regardless of whether the soundhole 142 extends to a plane
above the top cover 122, as defined parallel to the Z axis, the
configuration of the soundhole 142 optimizes the sound properties
of the instrument 122 by reversing the acoustic phase of sound
waves within the chamber 152 to alter at least one resonant
frequency, and/or frequency range, of the instrument 140. Hence,
the soundhole 142 provides structure along with the single chamber
152 to artificially enhance the acoustic properties of the
vibrating strings proximal a ported enclosure. In other words, the
soundhole 142 and single chamber 152 result in operational
acoustical advantages that would otherwise not be available by
positioning a port in an instrument body 108 having an internal
cavity volume, which distinguishes the present embodiments from
acoustic, hollow body electric, and semi-acoustic guitars.
[0033] FIG. 4 depicts a cross-sectional line representation of a
portion of an example stringed instrument 190 configured in
accordance with various embodiments to exhibit optimized acoustic
properties. The soundhole 142 continuously extends from the top
cover 122 into one or more internal cavities 124 with a smooth
sidewall 192 that defines the acoustic profile of the soundhole 142
with its length, shape, and diameter. In the non-limiting example
of FIG. 4, the sidewall 192 has a curvilinear portion 194 and a
linear portion 196. The curvilinear portion 194 can be
characterized as having a uniform radius (R), such as 0.375'' in
the Y-Z plane, along with a soundhole shape, such as circular,
oval, square, or parallelogram, in the X-Y plane parallel to the
top cover 122.
[0034] The acoustic profile of the soundhole 142 contacts the
linear portion 196 with the curvilinear portion 194 at a
predetermined depth 198 within the body 108, as measured parallel
to the Z axis from the top of the internal cavity 124, as shown.
The linear configuration defines a uniform inner diameter 200
parallel to the X-Y plane while the curvilinear portion 194 defines
a variable inner diameter 202 that is no smaller than the uniform
inner diameter 200.
[0035] The sidewall 192 continuously extends to an overall length
204, as measured parallel to the Z axis, that is selected to ensure
sound wave phase reversal in a manner similar to a Helmholtz
resonator. That is, the soundhole 142 separates the internal
portions of the body 108 from the strings, and outside ambient air,
with a length that causes sound waves inside the body 108 to
reverse phase within the soundhole 142. It is noted that the
soundhole length 204 can be a function of the diameter(s) 200/202
as well as the resonant frequency at which phase reversal is
guaranteed. As a result, some acoustic frequencies may not
experience phase reversal within the soundhole 142, but all
acoustic frequencies within a tuned range will experience phase
reversal.
[0036] As a non-limiting example, the soundhole 142 may have a
length of 1.125'', a uniform diameter of 2.375'', and a variable
diameter of 2.375-2.975''. The soundhole 142 may be constructed of
any type of material, but in some embodiments is a solid natural
wood, such as mahogany, ash, spruce, or cedar, that promotes
acoustic richness and/or depth. However, portions of the soundhole
142 are contemplated to be non-wood materials, such as metal,
ceramic, polymer. Portions of the soundhole 142 can be coated in a
material, such as resin, wax, or filler, that increases the density
of underlying material. At least some of the soundhole 142 can be
shaped or textured, to promote laminar airflow, such as with
dimples, ridges, grooves, or cantilevered protrusions that extend
into, or out of, the soundhole diameters 200/202.
[0037] While the interior sidewalls of the soundhole 142 can be
tuned to optimize airflow and acoustic operation, the exterior of
the soundhole 142 may also be tuned. For instance, a portion of the
soundhole 142 can be removed via one or more notches 206 that allow
the soundhole 142 to fit in a matching cover notch 208. The
exterior of the soundhole 142 may be configured to provide physical
support for the top cover 122 by physically contacting more of the
top cover 122 than the soundhole rim 176, as provided by the notch
206 size and shape. It is noted that the soundhole 142 may be
affixed to the top cover 122 with any adhesive, such as glue or
epoxy, or may have strictly a friction fitment, such as
tongue-in-groove, with no adhesive or artificial affixing
means.
[0038] As displayed in FIG. 4, the top cover 122 can provide a
continuously curvilinear transition region 210 where the exterior
top cover surface 212 transitions to the linear portion 196 of the
soundhole sidewall 192. The transition region 210 can be tuned to
promote laminar fluid flow while guaranteeing acoustic phase
reversal, such as by configuring the transition region 210 to
match, or be dissimilar to, the downhole curvilinear portion 194.
It is contemplated that the transition region 210 is incorporated
into the soundhole 142 instead of being part of the top cover 122,
which would result in the soundhole 142 continuously extending
through the top cover 122, as shown by segmented lines 214.
[0039] The ability to tune the configuration of the soundhole 142
allows some frequencies to be enhanced by raising, or lowering, the
resonance frequency of the body 108. In yet, a static tuned
configuration of a soundhole 142 may not be desirable to users that
want to alter different resonant frequency and/or frequency ranges.
Accordingly, various embodiments provide an adjustable soundhole
that can be manipulated by a user to change the frequency, and
frequency range, in which acoustic phase reversal is guaranteed.
FIG. 5 illustrates a cross-sectional line representation of
portions of an example stringed instrument 220 employing a variable
soundhole 222.
[0040] It is contemplated that a soundhole 222 can be arranged to
accept one or more inserts 224 that are rigidly attached, such as
with at least one fastener or with a friction fit within the
soundhole bore 226. Friction fitment may involve accessories, such
as a clip, spring, or shim, that increases the surface pressure
forced onto the soundhole 222, insert 224, or both. The soundhole
222 may have a structural feature 228, such as a groove,
protrusion, aperture, or ridge, that physically engages portions of
the insert 224 to prevent unwanted insert 224 movement or
vibration. For example, the insert 224 may physically fit within
the soundhole 222 and be retained with the aid of a threaded
engagement, an accessory applying force, and/or a keyed
configuration.
[0041] It is noted that the soundhole 222 may operate alone as an
acoustic phase reversing feature, similar to the soundhole 142 of
FIG. 4, and the insert 224 merely alters the physical configuration
of the underlying soundhole 222. As a non-limiting example, the
insert 224 may provide a different length 230, diameter 232,
sidewall shape, transition region 234 shape, and curvilinear
portion 236 shape that results in a different acoustic profile than
the underlying soundhole 222, as shown. However, some embodiments
construct a single soundhole 222 to be interchangeable by a user so
that a first soundhole with a first acoustic profile can be wholly
removed and replaced by a second soundhole with a different second
acoustic profile. Such a single, interchangeable soundhole 222 can
attach to the instrument body 108 in a variety of different
manners, such as a keyed joint, buckle, clip, or friction fit,
[0042] A variable soundhole 222, in some embodiments, is an
adjustable assembly constructed as a single unit that can be
articulated by a user, such as through rotation of a central member
with respect to an outer member and the instrument body 108. The
ability to easily and efficiently alter, or replace, a first
soundhole 222 that is tuned to change the resonant frequencies in a
first range to a second soundhole/insert that is tuned to change
the resonant frequencies in a different second range allows the
stringed instrument 220 to be more versatile and conducive to
different types of music reproduction, such as blues, rock,
classical, and jazz.
[0043] FIG. 6 displays a line representation of portions of another
example stringed instrument 240 constructed and operated in
accordance with various embodiments. The stringed instrument 240 is
shown from a rear perspective in FIG. 6 and has a body 108 affixed
to a neck 110 with strings 112 suspended from a bridge 116 towards
a headstock, as conveyed in segmented lines.
[0044] While some embodiments position a soundhole directly under
the strings 112, as shown in FIG. 3A, other embodiments position
one or more soundholes away from the strings 112 on the body 108.
For instance, a first soundhole 242 can be located on a rear
surface 244 of the body 108 and a second soundhole 246 is
positioned on a side surface 248 of the body 108, as illustrated in
a cutaway portion of the body 108. Each soundhole 242/246 is offset
from the strings 112 as well as from the top cover of the body 108.
In such a non-limiting example, the first soundhole 242 can be
tuned with different acoustic profiles, such as with a different
physical size, shape, and sidewall profile, than the second
soundhole 246. In yet, various embodiments arrange the soundholes
242/246 to have matching acoustic profiles.
[0045] A soundhole 242/246 can be arranged to be covered, and
potentially sealed, by a plate, grill, or other material, which
allows a user to alter the acoustic behavior of the instrument 240
at will. It is contemplated that soundholes 242 and/or 246 can
complement a string-aligned soundhole on the top cover of the body
108, but such configuration is not required or limiting. The use of
multiple soundholes 242/246 can correspond with a single port for
each separate chamber internal to the body 108 to prevent an excess
of airflow from any single internal chamber that can degrade
acoustic quality of the instrument 240.
[0046] The ability to selectively open, and close, multiple
soundholes in a single instrument body 108 allows the instrument
240 to be widely adaptable to enhancing different resonant
frequencies, and frequency ranges. Such multiple soundhole
configuration can be an alternative to the soundhole insert 224 or
variable soundhole assembly that allows a user to direct sound
waves in different directions that outward from the top cover of
the body 108.
[0047] FIG. 7 is a flowchart of an example stringed instrument
optimization routine 260 that can be executed with the various
embodiments conveyed in FIGS. 1-6. Initially, a stringed instrument
is constructed in step 262 with at least one soundhole. Step 262
may fabricate a hollow body electric/semi-acoustic guitar from a
solid body by forming one or more chambers that are sealed by a top
cover. A soundhole with a tuned acoustic profile (size, length,
diameter, and sidewall shape) may be positioned anywhere on the
body in step 262, but is supported by a suspension in some
embodiments to be aligned with a neck, headstock, bridge, and
strings, as shown in FIGS. 3A-3C.
[0048] Instrument construction in step 262 can involve factory
tuning where technicians optimize the soundhole acoustic profile,
perhaps by testing multiple different soundholes, for the
as-constructed body. For instance, a fabricated instrument body may
have slightly different internal chamber dimensions and volume that
is accommodated in the factory by testing multiple different
soundhole acoustic profiles in order to ensure acoustic phase
reversal for a particular frequency, such as 147 Hz, or for a
selected frequency range, such as 140-250 Hz. Once the resonance of
the constructed body has been optimized, step 262 finalizes factory
fabrication by installing and setting up the instrument for musical
playback. That is, the instrument may not be in tune, but is
complete and ready to produce sound and music.
[0049] In some embodiments, step 262 involves attaching
electronics, such as pickup(s), circuit boards, circuitry, knobs,
and tuners, to the body to allow the instrument to be played via a
separate signal processor. Such electronics can be a magnetic type
that differs from piezo type electronics that respond to the
vibration of strings found on acoustic-electric instruments. The
inclusion of electronics allows step 264 to connect the stringed
instrument to at least one signal processor, such as a pedal,
amplifier, or pre-amplifier. Articulation of the strings in step
266 produces sound waves that are concurrently generated within the
internal chamber of the instrument housing, received by the
electronic pickup(s), and received by the internal chamber(s) via
one or more soundholes.
[0050] The sound waves in step 266 are received, or generated, by
the internal chamber(s) at a first acoustic phase that is
reverberated within the chamber(s) before exiting the body via the
same soundhole(s) at a phase inverse from the first acoustic phase.
Hence, whatever acoustic phase initially entering the internal
chamber will be out-of-phase with the acoustic phase of the exiting
sound waves by 180 degrees. The combination of internal chamber
volume and acoustic phase reversal modifies the resonance frequency
of the instrument body while altering the acoustic properties of
the sound waves resulting from the string vibrations. As a result,
the stringed instrument will have an enhanced acoustic quality
proximal the instrument while providing an electronically
reproducible signal to the connected signal processor(s).
[0051] Music and other sounds can be continuously or sporadically
played by a user via the instrument in step 266 for any amount of
time. However, decision 268 can evaluate if the user would like to
alter the acoustic properties of the instrument. If so, step 270
modifies at least one soundhole, such as by inserting an insert,
installing a cover to seal a soundhole, or articulating a soundhole
member to change the acoustic profile of the soundhole. If not,
routine 200 returns to step 266 so that sound can continuously, or
sporadically, be generated at will. Decision 268 and step 270 can
be revisited any number of times to retune the instrument so that
different frequencies, or frequency ranges, result in an acoustic
phase reversal. As a result of step 270, a user can materially
contribute to the tonality, acoustic quality, and resonance of the
stringed instrument that can be appreciated whether or not the
instrument is connected to an exterior signal processor.
[0052] Through the various embodiments of this disclosure, a
stringed instrument can be tuned to alter the acoustic properties
than the instrument body. The use of one or more soundholes with a
smooth radiused transition to the top cover of an instrument allows
a relatively small internal body cavity to convey rich, deep, and
pure tonality across a range of frequencies due to the resonance
frequency of the instrument body being altered by the soundhole(s).
The ability to change an existing soundhole via an insert with a
different acoustic profile, such as length, sidewall shape, and
diameter, allows a user to manipulate the acoustic performance of a
stringed instrument at will.
[0053] It is to be understood that even though numerous
characteristics and advantages of various embodiments of the
present disclosure have been set forth in the foregoing
description, together with details of the structure and function of
various embodiments of the disclosure, this detailed description is
illustrative only, and changes may be made in detail, especially in
matters of structure and arrangements of parts within the
principles of the present disclosure to the full extent indicated
by the broad general meaning of the terms in which the appended
claims are expressed.
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