Apparatus and method for modifying responsive liquid held in liquid container having resonant frequencies in audio frequency range

Abstract

To provide a method for modifying a liquid in a container by supplying vibrational energy in the audible frequency range to the liquid in a container.SOLUTION: There is provided a method of agitating a vibration responsive liquid in a container comprising: deploying vibration responsive sensors in or on a container 11 containing a vibration responsive liquid; coupling vibrational energy directly to the container, which is within the audio frequency spectrum; determining the frequency response of the container with the vibration responsive liquid contained therein, from the outputs of the deployed sensors; determining the frequencies that can effectively excite vibrational energy in the liquid contained in the container, using the determined frequency response of the container and liquid; and coupling vibrational energy directly to the container using audio input signals 91 containing the frequencies determined in the foregoing step.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] This invention relates to a process for modifying a liquid contained in a liquid container, the liquid being responsive to vibrational energy introduced into the liquid, and more particularly to an apparatus and process for introducing acoustic energy into the liquid for the purpose of achieving a desired change in the liquid in a relatively short period of time. The invention has particular application in accelerating the maturation of alcoholic beverages, such as whiskey or wine, stored in wooden barrels or casks. [Background technology]

[0002]

[0002] Alcoholic beverages, and particularly whiskey spirits and wine, are traditionally aged in wooden barrels or casks, a process that changes the properties of the beverage over time, giving it a more desirable quality and taste. Aging is the final stage of the spirits or winemaking process. It allows the beverage to "mature" and is sometimes referred to as "finishing" the beverage. However, aging is characterized by contributing to the beverage's final, distinctive properties, including its color and flavor.

[0003] Because proper aging of whiskey or wine can take many years, different methods have been proposed to accelerate the physical and chemical changes underlying the aging process. These include subjecting the liquid in the barrel to ultrasonic vibrations and playing loud audible sounds, such as music, against the barrel. In both cases, the goal is to agitate the beverage inside the barrel to speed up the physical and chemical processes required to accelerate aging. The drawback to these acoustic approaches is that introducing energy in the ultrasonic frequency range causes cavitation in the liquid in the barrel, which is detrimental to the maturation process of the spirits or wine (or other liquid in the barrel), while in the lower audible frequency range, especially in the low audible frequency range where barrel resonance is found, it is difficult to introduce enough sound energy into the liquid in the barrel to have any significant effect on the aging process.

[0004] The present invention overcomes the obstacles of previously proposed acoustic aging processes by providing an apparatus and method for effectively coupling vibrational energy within the audible frequency range, and particularly within the range of about 20 Hz to about 1000 Hz, into a liquid in a barrel that is responsive to the agitation caused by this vibrational energy. By operating in these lower frequency ranges, the apparatus and method of the present invention avoid the problems of cavitation, which can lead to undesirable end results. The apparatus and method of the present invention are capable of introducing an effective amount of vibrational energy into whiskey, wine, or other agitation-responsive liquids contained in a barrel to effectively accelerate the aging of such liquids. The apparatus and method of the present invention further enable the accelerated aging of barrel liquids to be achieved with a limited amount of equipment and with relatively small external power requirements. Summary of the Invention [Means for solving the problem]

[0005] The present invention is directed to an apparatus for modifying a liquid held in a liquid container having a container wall, the liquid being responsive to vibrational energy introduced into the liquid, the container having a determinable resonant frequency within the audio frequency range. The apparatus includes a transducer capable of generating vibrational energy within the audio frequency range in response to a signal input. A coupling device, or simply a "coupler," having a protruding extrusion end is provided so that the vibrational energy generated in the transducer is transmitted to the coupling device. Mounting means are provided for holding the transducer adjacent the wall of the liquid container so that the pushing end of the coupling device fixed to the transducer presses against the wall of the liquid container and so that vibrational energy generated by the transducer at the resonant frequency of the liquid container is effectively transmitted through the container wall to the reactive liquid within the container.

[0006] The method of the present invention involves first determining the frequency response, and thereby the resonance, of a keg with a vibration-sensitive liquid contained therein, and then directly coupling to the keg vibrational energy using an audio signal containing a frequency based on this determined keg resonance. Direct coupling can be achieved by direct physical contact or indirect contact, whereby the vibrational energy is transmitted directly to the keg container wall.

[0007]

[0007] The method of the present invention extends to a method for improving the quality of alcoholic beverages contained in barrels, and most preferably wooden barrels, comprising the steps of: selecting a transducer capable of generating sound energy within a sonic frequency range; ii) mounting the transducer on the outside of a barrel containing the liquid alcoholic beverage to be aged so that the sound energy generated by the transducer is transmitted to the barrel; iii) positioning at least one sensor to detect pressure fluctuations or acceleration changes indicative of agitation in the liquid alcoholic beverage in the barrel when the transducer mounted on the barrel is excited at different frequencies, the sensor having a sensor output; iv) determining from the sensor output the resonant frequency(ies) of the barrel within the sonic frequency range of the transducer; and v) driving the transducer with a signal comprising a sufficient amount of sound energy at the determined resonant frequency(ies) of the barrel to cause resonance(ies) in the barrel which improves agitation of the alcoholic beverage in the barrel. [Brief explanation of the drawings]

[0008] [Figure 1]

[0008] FIG. 1 is a top perspective view of a barrel for holding whiskey, wine, or other agitated reactive liquid, with a device according to the present invention including a transducer secured to the barrel. [Figure 2]

[0009] FIG. 2 is a side view of the barrel of FIG. 1. [Figure 3]

[0010] FIG. 2 is an end view of the barrel of FIG. 1. [Figure 4]

[0011] FIG. 1 is an enlarged cutaway view of the bottom of the barrel and the transducer of the device in greater detail. [Figure 5]

[0012] FIG. 5 is a partially cutaway perspective view of the transducer seen in FIGS. 1-4, showing a coupler used to transmit vibrational energy generated by the transducer to the wall of the barrel. [Figure 6]

[0013] FIG. 2 is a cross-sectional view of the transducer shown in the previous figure. [Figure 6A]

[0014] 7 is an enlarged fragmentary view of the transducer of FIG. 6 showing in more detail how the base of the coupler is secured to the voice coil assembly of the transducer. [Figure 7]

[0015] 7A and 7B are perspective views of a transducer such as that shown in FIGS. 5 and 6, showing an alternative configuration for the coupler device of the apparatus. [Figure 8]

[0016] 5 shows the barrel illustrated in FIGS. 1-4 supported on a support stand and an alternative method of securing portions of the transducer in place on the barrel. FIG. [Figure 9]

[0017] 1 is a flowchart illustrating the steps of a method for determining the frequency response and thus the resonance of a barrel containing a liquid, and advantageously using the determined resonance to excite vibrations in the liquid contained in the barrel. [Figure 10]

[0018] FIG. 10 is a diagram of an electronic circuit for driving and controlling the output of the transducer shown in the previous figure. DETAILED DESCRIPTION OF THE INVENTION

[0009]

[0019] The embodiments of the invention described herein are directed to accelerating the aging of whiskey or other alcoholic beverages stored in barrels. However, it should be understood that the invention is not intended to be limited to such use. The described apparatus and methods may likewise be used to amend liquids contained in liquid containers, including containers other than barrels, where the liquid is responsive to vibrational energy introduced into the liquid.

[0010]

[0020] Referring now to the drawings, Figures 1-4 show a keg 11 for containing an alcoholic beverage, not visible, having a curved side wall 15 and a flat keg end wall 17. The keg is oriented horizontally, with the keg end wall in a vertical plane and the curved keg side wall extending in the direction of the keg's horizontal axis, indicated in Figure 2 by the letter X. While other keg orientations can be used, this orientation allows for advantageous placement, described below, of a transducer used to agitate the liquid within the keg. The liquid within the keg can be whiskey, although other vibration-responsive liquids, such as wine, can be processed within the keg as described herein.

[0011]

[0021] The central component of the apparatus and method used to generate vibrational energy that can be transmitted to the reactive liquid stored in the barrel 11 is the transducer 19. The transducer is preferably positioned between the barrel's end walls 17 at the bottom side 21 of the barrel, such that it is held in a position facing the barrel side wall and the transducer axis, indicated by the letter "A" in Figure 4, is in a vertical orientation. The transducer may be positioned at other locations along or around the barrel, but in the case of a single transducer, the illustrated location and vertical orientation of the transducer has been found to achieve the most efficient results in terms of amending the liquid in the barrel, particularly when the liquid is whiskey.

[0012]

[0022] The transducer 19 illustrated in the drawings is a cone driver, such as found in conventional loudspeakers, capable of generating vibratory motion within the audible frequency range. However, it is contemplated that other forms of transducers may be used, so long as they are capable of generating vibratory motion in the audible frequency range and particularly in the lower frequency regions of that range. Frequencies of particular interest are the resonant frequencies of the keg, which depend on the size and shape of the keg, as well as the keg material, wall thickness, and degree of filling of the keg; however, generally, frequencies of interest are expected to fall within the range of about 20 Hz to about 1000 Hz. It is at these resonant frequencies that the vibratory motion can be effectively and efficiently transmitted to the reactive liquid within the keg, according to the apparatus and method of the present invention. This requires effective coupling of the vibratory motion of the vibrating portion of the transducer to the keg sidewall 15.

[0013]

[0023] The illustrated transducer 19 and the mechanism for coupling the vibrational energy generated by the transducer to and through the barrel wall will now be described with reference to Figures 5-6 and 6A. As mentioned, the illustrated transducer 19 is in the form of a cone driver, preferably a 12 inch cone driver, having a durable yet lightweight paper cone diaphragm 23 suspended within a metal skeleton 24, referred to as a "basket," by a lower "spider" suspension 25 and an upper "perimeter" suspension 27. The transducer further includes a voice coil assembly consisting of an elongated cylindrical former 29 and a voice coil 31 wrapped around the lower part of the former. (As explained below, voice coil assemblies of conventional design for cone drivers also typically include a paper material, not shown, wrapped around the former above the voice coil to provide a better adhesive surface for the driver diaphragm.) The cone diaphragm is fixed to an axial extension 28 of a cylindrical former for the voice coil, which is positioned within the magnetic gap of a magnetic circuit created by a collection of magnets 32, magnetically permeable top plate 33, and pole pieces 35 (collectively referred to herein as the "magnetic circuit assembly"). The pole pieces are seen to have a central through hole 34, the lower part of which may be covered by a screen such as screen 36 shown in FIG. 6.

[0014]

[0024] In use, when an AC voltage input signal in the audio frequency range is applied to the driver, it generates a current in the voice coil corresponding to the input signal, which in turn generates a vibratory motion throughout the voice coil assembly, and the vibratory motion in the voice coil assembly in turn drives the cone diaphragm in a vibratory motion. In a typical cone driver, the sole purpose of the vibratory motion of the diaphragm is to generate sound. Here, however, the vibratory motion of the voice coil assembly is utilized for another purpose. By transmitting the vibratory motion to the illustrated coupler 37, the vibrational energy generated by this motion is coupled to the wall of a barrel containing a liquid that is responsive to vibrational energy.

[0015]

[0025] 5, 6, and 6A, coupler 37, preferably fabricated from a rigid-plastic material exhibiting low internal damping, such as acrylic or ABS plastic, can be seen to have a substantially closed, forward-projecting extruded end 39 that projects beyond the front face of the transducer (designated by the letter P in FIGS. 4 and 6), and a cylindrical sidewall 41 that extends rearward from the extruded end into the transducer cone. The coupler's cylindrical sidewall can be seen to have a cylindrical recess 43 extending upwardly from a proximal end 45 of the sidewall inside the coupler sidewall for receiving the cylindrical extension 28 of the voice coil former 29. The proximal end of the coupler sidewall is secured to at least one, and preferably both, a lower rim portion 47 of the driver's cone diaphragm and the cylindrical extension of the voice coil former by a suitable adhesive, such as a urethane adhesive or epoxy. The adhesive may be applied to the areas indicated by the letter "R" in Figure 6A, i.e., the lower rim portion 47 of the cone diaphragm 23 and the outer surface of the cylindrical extension 28 of the voice coil former 29. It should again be noted that the outer surface of the cylindrical extension 28 of the voice coil former 29 is typically covered with a paper material, such as craft paper, for ease of adhesion to this surface.

[0016]

[0026] The coupler may further have notches in the sidewalls and extruded end of the coupler, as indicated by numerals 49, 51. These notches act as vents to allow air to escape from the coupler during vibratory motion of the transducer, and notch 49 in the coupler sidewall additionally provides an accessible strap hole through which the coupler may be strapped to a barrel or other structure, as described hereinafter.

[0017]

[0027] The transducer 19 must be held in place next to the barrel sidewall so that the extruded end of the coupler, which is attached to the transducer cone, makes firm contact with the sidewall 15 of the keg 11. In the case of the coupler illustrated in Figures 5-6, the barrel contact is made by a small, raised front contact surface 53, which concentrates the force transmitted through the coupler to the barrel wall. (This contact is best seen in Figure 4.) A strap 55, shown in Figures 1-4, serves as a tying means to hold the coupler in place. This strap, preferably made of a stable, low-stretch material such as polyester webbing, is threaded through the notches 49 in the coupler sidewall, wrapped around the barrel, and can be tightened to press the coupler against the barrel sidewall. What may be considered the rear of the transducer—the basket and magnet circuit assembly—is separately held in place by another tying means, which in this case is preferably a resilient tying means such as an elastic cord 57 that compliantly secures the transducer in place. The use of elastic tethers for the basket and magnet circuit assembly has been found to improve results by allowing the transducer to operate in its linear range.

[0018]

[0028] 7 shows a transducer 19 as previously described, with an alternative design for the transducer coupler. In this case, the transducer coupler 61 is in the form of a right cylinder with an upper rim 63 that acts as the extruded end of the coupler. In this case, the extruded end of the coupler is open, instead of having a closed configuration as in the previously described embodiment. A notched opening 67 in the cylindrical side wall 69 is provided to receive one or more securing straps, such as straps 55 shown in Figures 1-4, for holding the coupler against the barrel wall. As with the previously described coupler embodiment, the extruded end formed by the coupler's upper rim 63 protrudes beyond the front face of the transducer so that when the transducer is mounted to the side wall as described above, only the extruded end of the coupler contacts the barrel side wall. Here, contact is made on either side of the coupler's upper rim 63.

[0019]

[0029] The coupler embodiment shown in Figure 7 may also be preferably fabricated from a rigid-plastic material and similarly attaches at its proximal end to the transducer cone diaphragm and / or the voice coil former of the transducer's voice coil assembly. This embodiment of the coupler is easier to fabricate and easier to strap to the barrel. The sidewall of the barrel may be modified to increase the surface contact area between the extruded end of the coupler and the barrel wall, although this is not required.

[0020]

[0030] FIG. 8 shows a whiskey keg 11a, similar to keg 11 shown in FIGS. 1-4, supported on a keg support stand 70, and additionally shows a transducer 19 coupled to the keg as described above. The keg support stand is configured to support the keg in its preferred horizontal position. However, instead of being tied directly to the keg as shown in FIGS. 1-4, the transducer basket and magnetic circuit assembly ("TBMCA") is resiliently tied to the keg support stand by a resilient tying means, such as bungee cords 71 ​​shown in FIG. 8. Preferably, there are two bungee cords on each side of the keg, with hook ends 72 of the bungee cords fastened to the transducer basket at one end and to a suitable portion of the support stand at the other end, e.g., keg support projections 73 on the keg support stand frame. The illustrated straps 77 with fastening clamps 79 pass through the above-described notches in the coupler side walls to tie down the transducer coupler to the keg wall, also as described above. An additional adjustable strap 78, which is also wrapped around the keg, is provided for tying the keg to a support stand. In both cases, the strap is preferably made of a stable, low-stretch material and is pulled tight around the keg.

[0021]

[0031] The different ways of tying the transducer to the barrel wall described above (wrapped and tied to the barrel using bungee cords as illustrated in the figures, or tied to a stationary frame) result in the transducer basket and magnetic circuit assembly being held in place elastically, rather than in a fixed, stationary position, as would typically be the case if the transducer were mounted to the baffle wall of a loudspeaker enclosure. The elastic tethering means for the TBMCA actually creates a dual-moving mass system on a spring. The primary moving mass is the TBMCA itself, which is coupled by a spring (the diaphragm suspension) to a second moving mass consisting of the voice coil assembly, coupler, and barrel ("VCB") (the diaphragm is essentially massless). It should be noted that when the TBMCA is coupled directly to the barrel, the TBMCA mass is also coupled (elastically tethered) to the VCB mass by a secondary spring, thereby providing a secondary path for the TCBMA's vibrational energy to be coupled to the barrel (actually the VCB mass) and hence to the liquid within the barrel. However, in this direct coupling configuration, it is believed that the TCBMA's vibrational energy reaching the liquid within the barrel via this secondary path is relatively small, and that the majority of the TCBMA's vibrational energy transmitted by the VCB mass to the liquid within the barrel is transmitted through the primary path of the coupler by the diaphragm suspension.

[0022]

[0032] The apparatus described above can be advantageously used to excite resonances in a barrel (or other container) within the audio frequency range of interest, which occurs mostly below 1000 Hz. By driving the transducer at or near these resonant frequencies, the vibrational energy generated by the transducer can be efficiently transmitted to the liquid within the barrel. At these frequencies, the barrel walls are effectively transformed into a substantially massless vibrating plate that directs vibrational energy into the liquid in the barrel, stirring the liquid, for example to accelerate the maturation of the spirits contained within the barrel. The signal components driving the transducers fixed to the barrel need to be optimized to the barrel resonant frequencies. This optimization can be done either manually or via a feedback loop.

[0023]

[0033] Manual techniques for optimizing signal content involve an open-loop system in which sensors (e.g., accelerometers or hydrophones) deployed in or on the barrel are manually used to measure the "energy spectrum" and / or "transfer function" (frequency response) to identify the barrel's resonant frequencies. These measurements can be performed using a single- or dual-channel FFT spectrum analyzer, although other analysis methods can also be used. As part of this manual adjustment process, boost equalization can be applied to the audio path at the resonant frequencies so that the input signal can best excite the resonance and maximize vibration. This manual process can be repeated at predetermined time intervals (days / weeks / months) throughout the aging process to adjust for resonance changes if the resonance should drift.

[0024]

[0034] The manual approach described above for optimizing the signal components is reflected in FIG. 9, which is a flowchart illustrating the basic steps for generating resonance within a keg to agitate the reactive liquid therein to a sufficient degree to produce a desired effect, such as accelerating the aging of whiskey. As a first step, a vibration sensor, as described above, is deployed to measure vibrations within the keg walls (acceleration) and, preferably, vibrations in the liquid contained in the keg (acoustic pressure). This step is represented by block 81. Next, vibration energy is directly coupled to the keg within the audio frequency spectrum (block 83). The output of the deployed sensor is then used to determine the frequency response of the keg with the vibration-reactive liquid contained therein (block 85). Using the determined frequency responses of the keg and the liquid, a frequency (agitation) that can effectively excite vibrational energy within the liquid contained in the keg is determined (block 87). In the next step of the method (represented by block 89), vibrational energy is coupled directly to the barrel (such as by the apparatus described above) using an audio input signal containing the frequencies determined in the previous step (block 87). At the determined resonant frequencies, the vibrational energy needs to be sufficient to excite effective vibrations within the liquid contained in the barrel. Direct coupling of sound energy to the barrel results in efficient coupling of vibrational energy to the liquid within the barrel, meaning that less power is required to effectively agitate the barrel liquid at these resonant frequencies compared to playing sound loudly against the barrel.

[0025]

[0035] FIG. 10 illustrates a simple system for optimizing the signal components input to a transducer using a feedback loop. Shown is a signal input 91 and signal path to a transducer 19, including a signal processor 93, a limiter 95, and an amplifier 97. The amplifier output is connected to the transducer 19, which may be fixed to the barrel 11 in the manner described above or to a stationary support stand as illustrated in FIG. 8. A sensor, designated by the letter A, is deployed within the barrel to measure the acoustic pressure within the liquid in the barrel induced by vibrations from the transducer. An additional sensor, designated by the letter B, is mounted on the outside of the barrel wall to measure acceleration within the wall. The sensor output is used to detect resonance, as indicated by block 99, and this information is fed back to the signal processor 93. Different types of feedback systems are contemplated, which will now be described more briefly.

[0026]

[0036] Classical negative feedback system. In this system, the sensor output is fed back to a linear controller (such as a PID or possibly a MIMO controller) to form a negative feedback. Classical control theory applies here. A difference signal is generated and used to drive an amplifier and transducer. As in a typical negative feedback system, the signal at the sensor is forced to match the signal at the input thanks to loop gain. In this case, acceleration (sensed by an accelerometer) matches the electrical audio input. The electrical input is an external audio signal and possibly also an internal audio signal mixed with it. The internal audio signal can be, for example, a sine wave set at a known resonant frequency to keep the acceleration at a nearly constant magnitude, thereby producing optimal vibration and fluid agitation.

[0027]

[0037] In classical negative feedback, the degree to which the sensor signal matches the input depends on the amount of loop gain. Loop gain is always limited to achieve stability. Stability of a negative feedback system requires the absence of positive feedback at frequencies where the loop gain is greater than or equal to one. Because phase shift increases with increasing frequency due to delay between the actuator and sensor ("plant"), roll-off is often applied in the loop in the form of a low-pass filter, i.e., a dominant pole, to ensure that the gain is <1 before the phase reaches 180°. Because the roll-off itself also introduces a phase shift, it is typically limited to first order (-6 dB / octave). Loop gain at frequencies below this unity gain frequency can typically only increase by 6 dB / octave (with decreasing frequency). [Example]

[0028]

[0038] When the phase shift from a transducer was measured with an accelerometer in a barrel containing whiskey, it was observed that the phase shift reached 180 degrees by 300 Hz, even when the accelerometer was placed very close to the driver. As a result, large amounts of loop gain could not be applied, since the gain had to be <1 from 200 to 300 Hz. To keep the feedback loop stable, a maximum of 20 dB of loop gain needed to be applied at 25 Hz, ramping to 0 dB loop gain at 250 Hz. The drawback of this approach is that it results in relatively poor tracking of acceleration.

[0029]

[0039] Automatic Measurement & Monitoring with Automatic Adjustment. In this embodiment, the accelerometer sensor is not in a negative feedback loop, but instead its signal is fed to a system that automatically measures the spectrum, transfer function, or other properties to make decisions regarding the equalization of the audio fed to the amplifiers and actuators. This system can take a variety of forms. It may, for example, drive an amplifier to optimize or maximize acceleration at a resonant frequency, adjusting the equalization and overall gain in the audio. It may also adjust limiters or nonlinear signal processing, or activate an internal audio signal such as noise or a sine wave, again to optimize acceleration or vibration.

[0030]

[0040] Positive Feedback with Controlled Instability: The concept of this system is that positive feedback, rather than negative feedback, is implemented so that the loop is held by virtue of oscillation or weak oscillation at one or more of the resonant frequencies.

[0031]

[0041] Although various embodiments of the present invention have been described in considerable detail in the foregoing specification, it is not intended that the invention be limited to the described embodiments or to the particular details of the described embodiments. It will be understood that variations to the described embodiments are possible without departing from the scope and spirit of the invention.

Claims

1. 1. An apparatus for modifying a liquid held in a liquid container having a container wall, the liquid being responsive to vibrational energy in the audio frequency range introduced into the liquid, the apparatus comprising: a transducer capable of generating vibrational energy within the audible frequency range in response to a signal input; a coupler secured to the transducer such that vibrational energy generated by the transducer is transmitted to the coupler, the coupler configured to transmit vibrational energy generated by the transducer in response to the signal input to the wall of the container when the transducer is held adjacent to the wall of the container. Device.

2. The apparatus of claim 1 , wherein the coupler is configured to transmit vibrational energy generated by the transducer to the wall of the vessel by direct contact with the wall of the vessel.

3. 10. The device of claim 1, wherein the transducer has a defined front surface, the coupler has a protruding tip extending beyond the front surface of the transducer, and vibrational energy generated by the transducer in response to a signal input is transmitted to the wall of the container through direct contact of the protruding tip of the coupler with the container wall.

4. 2. The device of claim 1, wherein the transducer has a voice coil assembly that generates vibratory motion in response to a signal input, and the coupler is fixed to the voice coil assembly such that the vibratory motion of the voice coil assembly is transmitted to the coupler and to the wall of the container.

5. 5. The device of claim 4, wherein the coupler has a forwardly projecting extrusion end configured to contact the wall of the container and a proximal end secured to the voice coil assembly of the transducer.

6. 10. The apparatus of claim 1, further comprising fastening means for holding the transducer to a wall of the liquid container such that the coupler fixed to the transducer transmits vibrational energy generated by the transducer to the container wall and from there to the reactive liquid within the container.

7. 7. The apparatus of claim 6, wherein the tying means comprises means for fastening the coupler to the wall of the container so that the coupler remains in contact with the container wall.

8. 8. The apparatus of claim 7, wherein the means for fastening the coupler to the wall of the container comprises a notch in the coupler for receiving a tie-down strap or cord that wraps around the container.

9. 7. The device of claim 6, wherein the transducer includes a rear portion to which the coupler is free, and the tying means includes means for resiliently holding the rear portion of the transducer in place relative to the coupler and container.

10. 10. The device of claim 9, wherein the rear portion of the transducer is resiliently held directly against the container.

11. 1. An apparatus for modifying a liquid held in a liquid container having a container wall, the liquid being responsive to vibrational energy introduced into the liquid, the apparatus comprising: a transducer capable of generating vibrational energy in the audio frequency range in response to a signal input, the transducer having a defined front surface; a coupler having a base end and a pushing end extending beyond the front face of the transducer, the base end of the coupler being fixed to the transducer such that vibrational energy generated in the transducer is transmitted to the coupler, the pushing end of the coupler being configured to contact and push against the wall of the liquid container when the transducer is held against the wall of the container; An apparatus comprising:

12. 12. The device of claim 11, wherein the coupler includes a notch for receiving a tie-down strap or cord that wraps around the container to hold the extrusion end of the coupler in contact with the container wall.

13. 12. The device of claim 11, wherein the coupler includes a plurality of notches for vents and for receiving tie-down straps or cords that wrap around the container to hold the extrusion end of the coupler in contact with the container wall.

14. The device of claim 11 , wherein the coupler has a cylindrical sidewall extending from the proximal end of the coupler to the extrusion end of the coupler.

15. 12. The apparatus of claim 11, wherein the extrusion end of the coupler has a substantially closed end with a raised forward contact surface for contacting the wall of the container.

16. 12. The apparatus of claim 11, wherein the extrusion end of the coupler is open and is formed by a front upper rim of the coupler, the front upper rim of the coupler providing contact between the coupler and the wall of the container.

17. The apparatus of claim 11 , wherein the coupler has a cylindrical shape.

18. 1. An apparatus for modifying a liquid held in a liquid container having a container wall, the liquid being responsive to vibrational energy introduced into the liquid, the container having a determinable resonant frequency within the audio frequency range, the apparatus comprising: a transducer having a voice coil assembly for generating vibrational energy within the audio frequency range in response to a signal input, including one at the determined resonant frequency of the container, the transducer having a defined front surface; a cylindrical coupler having a base end and a protruding end extending beyond the front face of the transducer, the base end of the coupler being fixed to the voice coil assembly of the transducer such that vibrational energy generated by the voice coil assembly is transferred to the coupler, and the protruding end of the coupler being configured to contact and push against the wall of the liquid container; a tethering means for holding the transducer adjacent to a wall of the liquid container such that the extrusion end of the coupler fixed to the transducer presses against the wall of the liquid container, so that vibrational energy generated by the transducer at the resonant frequency of the liquid container is transmitted through the container wall to the reactive liquid in the container; and An apparatus comprising:

19. 20. The device of claim 18, wherein the tying means includes a plurality of notches for vent holes and a tying strap or cord that wraps around the container to hold the extrusion end of the coupler in contact with the container wall.

20. 20. The apparatus of claim 19, wherein the transducer includes a stationary rear portion to which the coupler is not secured, and the fastening means includes means for resiliently holding the stationary rear portion of the transducer directly to the container.

21. 1. A method of agitating a vibration-sensitive liquid in a vessel, comprising the steps of: disposing a vibration-sensitive sensor in or on a vessel containing the vibration-sensitive liquid; coupling vibrational energy within the audio frequency spectrum directly into the vessel; determining a frequency response of the vessel containing the vibration-sensitive liquid therein from the output of the deployed sensor; using the determined frequency responses of the vessel and liquid to determine frequencies that can effectively excite vibrational energy in the liquid contained in the vessel; coupling vibrational energy directly into the vessel using an audio input signal containing the frequency determined in the previous step; A method comprising:

22. 22. The method of claim 21, wherein the step of determining frequencies that can effectively excite vibrational energy in the liquid contained in the vessel includes determining a resonant frequency(ies) of the vessel, and wherein the audio input signal is selected to include energy at such determined resonant frequencies to excite resonance in the vessel.

23. 22. The method of claim 21, wherein the vibrational energy is coupled directly to the vessel by the transducer having a coupler configured to physically contact a wall of the vessel to transmit the vibrational energy generated by the transducer to the vessel wall.

24. 24. The method of claim 23, wherein the container is supported in a horizontal orientation and the transducer is held in a vertical orientation adjacent a wall of the liquid container.

25. 1. A method for improving the quality of an alcoholic beverage in a wooden barrel, comprising: selecting a transducer capable of generating sonic energy within a sonic frequency range; - mounting said transducer on the outside of a keg containing said liquid alcoholic beverage to be aged such that sound energy generated by said transducer is coupled into said keg; positioning at least one sensor to detect acceleration changes in the container wall or pressure fluctuations in the liquid alcoholic beverage in the keg when the transducer attached to the keg is excited at different frequencies, the sensor having a sensor output; determining the resonant frequency(ies) of the barrel within the sonic frequency range of the transducer from the sensor output; driving the transducer with a signal containing energy at the determined resonant frequency(ies) to induce resonance(ies) in the barrel that improves agitation of the alcoholic beverage in the barrel; A method comprising:

26. The transducer generates acoustic energy in a sonic frequency range below about 1000 Hz.

26. The method of claim 25, wherein the transducer is a low frequency transducer for

27. 26. The method of claim 25, wherein determining the resonant frequency(ies) of the barrel within the sonic frequency range of the transducer is performed manually.

28. 26. The method of claim 25, wherein determining the resonant frequency(ies) of the barrel within the sonic frequency range of the transducer is accomplished by a feedback circuit connected to the sensor and transducer.

29. 26. The method of claim 25, wherein the barrel is supported in a horizontal orientation and the transducer is mounted in a vertical orientation to the bottom of the barrel.

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