Apparatus for the creation of a desirable acoustical virtual reality

A portable collapsible seat with an advanced five-driver integral audio system is disclosed. The seat is designed to be used in conjunction with a video screen to create an enhanced "virtual reality" environment. The placement of the drivers relative to the user's head, combined with the intentionally different bandwidths of sound produced by the different drivers, and the relative acoustical intensities of the drivers produces psychologically "gripping" effect, designed to transport the user away from the reality of the actual surroundings and into the virtual reality of the video presentation. One of the drivers is intentionally oriented and positioned to provide tactilly perceivable vibration through the seat to the user.

FIELD OF THE INVENTION 
The invention relates generally audio-visual virtual reality systems, and 
to video games and to arcade video games where the player is seated in a 
seat attached to the game while playing, and more specifically to sound 
systems used with video games, virtual reality apparatus, and personal 
video stations. 
BACKGROUND OF THE INVENTION 
Over the last decade, video games have been a popular form of entertainment 
for consumers. As the computation necessary to generate advanced 
full-motion graphics has steadily become cheaper, and algorithms for 
generating imagery on the fly have become more well developed, the average 
consumer has continued to make regular expenditures of discretionary 
income to upgrade home video game systems, and play the latest arcade 
video games. One of the draws of arcade video games and advanced home 
video games is the level to which the realism of the images enables the 
player to escape from the real world for a time and enter the fantasy 
world of the game. The graphics of top arcade games have gone from simple 
two-dimensional representations, to three dimensional representations with 
complex shading and textures, and the laws of physics well represented in 
how the three-dimensional characters and objects in the games interact. 
As the video images produced by top video games have taken staggering leaps 
forward in complexity over the last ten years, the sound tracks of these 
games have also advanced considerably, though not as much as the video 
images have advanced. This is partly due, perhaps, to the lack of 
significant advancement in the designs of the speaker systems that deliver 
the sound to the consumer who is playing the game. Most speaker systems in 
arcade video games remain quite similar to those of 10 years ago. These 
are either simple monaural speaker systems, or simple stereo speaker 
systems, usually mounted in the cabinet of the video game console, which 
is usually positioned in front of the consumer playing the game. 
As the sound tracks for these video games improve, they are getting closer 
to the level of quality found in the sound tracks of today's box office 
hit movies. These movies often contain amazing special effects. A sound 
track which creates an acoustic experience which "grips" the audience can 
be a key factor in transporting the audience into the artificial reality 
being created by the movie. In this vein, top-of-the-line video games will 
be using sound more and more to create the reality for the player of the 
game. As this trend continues, it is likely that audio systems for video 
games are likely to continue to improve in quality. Let's take a look at 
the nature of the "quality" that home audio system designers have striven 
for over recent decades. 
The reproduction of music, with desirable psycho-acoustical characteristics 
(such as might be experienced in a concert hall listening to a live 
performance) has been the objective of many in the audio industry for 
years. The modern pursuit of this goal has included implementations 
utilizing digital signal processing for the reconstruction of a sound 
field by measuring the acoustic response of the field and then modifying 
the input to an array of loudspeakers to produce the appropriate velocity 
and pressure within the fluid medium. 
Some hold that audio systems should be designed for the "exact" 
reproduction of a sound field that might be experienced by a listener in a 
concert hall. The exact reproduction of a sound field can be approached 
one of two ways. In the first way, a recording of the sound experience to 
be reproduced may be made on a binaural recording device which mimics the 
size and shape of a human head (including the ears). When played back 
through headphones, such a recording can be strikingly lifelike, with much 
of the spatial (directional) cues preserved. The disadvantage of this type 
of recording is that it is so highly optimized for headphone play-back; it 
does not sound as good as a "regular" stereo recording when played back 
through speakers which aren't right next to the listener's head. Another 
disadvantage of headphones is that their use may be cumbersome or 
impractical in some applications, and headphones used in public 
applications (such as in CD stores or arcades) are prone to reliability 
problems. 
The second way that one can approach the reproduction of a sound field is 
to produce a sound field with multiple speakers placed at different points 
in space, and fed different signals (hereinafter referred to as a 
"multi-channel" audio system). Stereo is the simplest such commonly 
employed approach. Such psycho-acoustic parameters as perceived "depth", 
"spaciality", "color", and "timbre" are generally agreed to be much 
improved in a stereo sound system, as compared with a monaural sound 
system. Driver characteristics such as linearity and frequency response 
also affect the perceived quality of the signal. 
Sound systems with more than two speakers also exist (though they are not 
as widely used as simple stereo). Such systems include Dolby 
Surround-Sound (used in theaters), and earlier attempts at "quadraphonic" 
standards. The problem in designing multiple-speaker systems beyond simple 
stereo is choosing a trade-off in the number of transducers, the placement 
of those transducers, the design of those transducers, and the signals fed 
to those transducers to economically produce a "desirable" 
psycho-acoustical effect. 
Trying to recreate a standard audio bandwidth (20 Hz-20 kHz) sound field to 
arbitrary accuracy throughout a room is a totally impractical problem. As 
detailed in a publication by Nelson, P. A., 1994, "Active control of 
acoustic fields and the reproduction of sound," Journal of Sound and 
Vibration, 177(4), pp. 447-477, to identically reproduce a sound field 
with an array of transducers over a frequency range extending from 20 Hz 
to 10 kHz and for a sphere of 10 m diameter would require over 1 million 
individual sources. 
Fortunately, the human auditory system is not measuring "everything" about 
the sound field. Some is known about what "key" things contribute to 
perceptions (perceptions such as "this sounds `real`, and this doesn't"), 
and a lot is still not known. An exciting opportunity exists in the field 
of audio to discover and design systems which, while much simpler than the 
above described one million transducers, provide highly desirable 
psycho-acoustical effects at reasonable prices, and are thus valued by 
consumers. 
One cost-saving innovation which has become quite widespread in modern 
stereo systems is the addition of a third "subwoofer" transducer to the 
original stereo model. The sub-woofer produces low-frequency sounds, 
usually below about 250 Hz. The human auditory system is not good at 
determining the source direction of such low-frequency sounds. Thus one 
transducer may be used as effectively as two, an the sub-woofer transducer 
may be placed anywhere in the room. In typical musical selections, these 
low frequencies account for most of the power that a loudspeaker set 
requires. They also account for most of the distance of cone-motion in 
loudspeakers. By removing the low frequencies from the stereo speakers, 
cone motion, and its associated nonlinearities (which cause distortion) 
are reduced. All these factors together allow the stereo speakers (in a 
system utilizing a subwoofer) to be manufactured in smaller, less 
obtrusive enclosures, with cheaper components, for less cost. The consumer 
gets a higher quality, more aesthetically pleasing system, for less money. 
Within stereo systems (with or without sub-woofers), the mid and high 
frequencies are often produced by separate transducers in the same cabinet 
(so-called "midrange" drivers and "tweeters"). While often not necessary 
from a distortion perspective, the splitting of mid and upper-range 
frequencies between two transducers is often desirable from the standpoint 
of obtaining a flat frequency response. Mid-range drivers often have 
numerous high frequency resonances, at which the amplitude of sound 
produced changes drastically. This produces a sound of less desirable 
quality. Another problem with mid-range drivers at high frequencies is 
that they typically produce widely varying sound intensities in different 
directions, thus, depending on where the listener is in the room (worse 
yet, if the listener is moving in the room) the listener may hear 
inconsistent or annoying quality variations from the speakers. 
In the past ten years, signal processing, and in particular, digital signal 
processing has allowed for the most significant breakthroughs in the quest 
for more psycho-acoustically pleasing sound reproduction. The quest for 
"accurate" reproduction of sound is ironic in some ways. Many have been 
assuming the need to accurately reproduce something, yet concert halls 
with the same (accurate, live, "real") sources in them have vastly 
different perceived qualities, even with no distortion. Taking this into 
account, one could hold that an ideal audio system could create new 
realities (or acoustic environments), not just reproduce known ones. Some 
of today's digital signal processing units have taken a cut at creating 
part of the reality (as the concert hall does). Digital signal processing 
audio units cannot, however, overcome some of the basic physical 
limitations imposed by the speakers we attach to them, such as the 
physical positions of the speakers in the room, and their directionality 
(radiation patterns) at different frequencies. 
We are a society undergoing a paradigm shift in our culture regarding 
entertainment. Today's movies and virtual reality games take us well 
beyond the thirst for reality in reproduction, into a thirst for things 
beyond what are "real", the thirst for new experiences which can be 
created. Musicians electronically create instruments that do not exist, 
which have pleasing musical characteristics. Special effects experts 
create entire visual worlds that do not (an indeed in some cases cannot) 
exist, and people pay higher and higher prices to experience these 
creations. Many of these creations put the observer in places where he or 
she cannot normally be ("in the experience", so to speak), such as 
standing next to a Tyrannosaurus Rex as it eats someone. The desire here 
is for the new, the vivid, the "more than real", but definitely not just 
"accurate reproduction of something previously experienced". 
As the demand for the ability for us to "enter the experience" grows, a 
significant market will form for in-home systems which can provide this 
"more than real" entertainment. New acoustical sound production paradigms 
(not just sound reproduction, because we want to make things "more" than 
real) will be in demand. 
It is an object of the present invention to provide an improved 
multi-channel audio system which, when playing today's film and video game 
sound tracks, provides a more involving "gripping" psycho-acoustical 
experience for the listener, transporting the listener more effectively 
into the virtual "reality" of the film or video game. It is a further 
object of the present invention to provide an improved multi-channel audio 
system which is superior to present-day stereo and other multi-channel 
audio systems, in such psycho-acoustical dimensions as "timbre", "color", 
"spatiality", and "depth". It is a further object of the present invention 
to provide an aesthetically pleasing, ergonomically superior multi-channel 
audio system. It is a further object of the invention to provide a 
multi-dimensional acoustical audio system that combines the selection of 
transducers, the placement of those transducers and the spectral 
separation of frequency to the transducers to optimize the 
psycho-acoustical effect to the user. It is a further object of the 
invention to provide the psycho-acoustical experience to the user with a 
focus on the binaural auditory system and tactile sensory system of the 
user and not the audio source. It is a further object of the invention to 
provide an easy-to-set-up, easy-to-store, portable seat for use with video 
games and the like, with integral sound and/or vibration which provide an 
enhanced virtual reality experience. 
SUMMARY OF THE INVENTION 
The present invention offers a quantum leap forward in the 
psycho-acoustical environment that can be created for the player of a 
video game, or "virtual reality" game. When using a system according to 
the invention, the user is presumed to be seated in a seat integral to the 
system. A common use of the system would entail setting up the apparatus 
as a viewing and listening station in which to sit and operate a video 
game or watch a video on a screen set up in front of the apparatus and the 
user. 
According to the invention, an apparatus for creating an acoustical virtual 
reality in connection with an audiovisual entertainment, such as computer 
video games, includes a seat having a seat back and a seat base connected 
along a joint line and a plurality of acoustics drivers, preferably 
loudspeakers, at least some of said loudspeakers being positioned on said 
seat structure and arranged at least to the left and right of the seating 
area with one speaker centered forward of the seating area. 
The positions of the three speakers can define a triangle wherein the line 
between the left and right speakers and a line between one these speakers 
and the third, central speaker form an angle of greater than 45 degrees. 
The apparatus can further include a sub-woofer for producing signals less 
than 100 Hz. The subwoofer is preferably mounted in the back portion of 
the seat with its axis of motion transverse to the support surface for the 
user's back, and particularly his lower lumbar region. The subwoofer is 
preferably dual-ported to the sides of the seat back, proximate the height 
of an average user's ear level. 
The apparatus can also include a high frequency device for producing 
signals above 16 kHz. The high frequency device is preferably placed above 
the left and right loudspeakers and behind the user's head. Thus, the high 
frequency device can be centrally placed along the top of the seat back. 
The left and right loudspeakers can be mounted on wings extending from the 
sides of the seat base. These speakers are preferably mounted facing 
upwardly through apertures providing circular deflectors. The central 
loudspeaker can be similarly mounted upwardly near a front end of the seat 
base and equipped with a circular deflector. 
According to another aspect of the invention, the apparatus provides a 
collapsible seat having at least a low frequency vibrational transducer or 
loudspeaker for tactile signal generation. The collapsible seat preferably 
is also equipped with other loudspeakers for generating a sound field as 
well. The seat can include an internal amplifier, and optionally, audio 
intensity limiters. 
The seat construction preferably includes a hinged assembly including a 
lower extension of the seat back that serves as a carrying handle during 
storage and transport and a resistive support in the open position against 
the user's back leaning. The hinge can include a detent latch for securing 
the seat in both the open and the closed position. The seat housing is 
preferably constructed to port the subwoofer with a dual tuned port 
system. The lower seat base can also be designed to port the back wave of 
the central loudspeaker to lateral sides of the seat base. 
Thus, the apparatus of the invention provides a seated environment for 
creating an acoustical virtual reality to enhance audio visual 
entertainment in connection with video games and the like. The system not 
only provides enhances audio but also tactile signals to the user.

DETAILED DESCRIPTION OF INVENTIVE EMBODIMENTS 
The invention is directed to a device for creating an audio and tactile 
virtual reality environment for a user seated on the device to enhance the 
experience in audio-visual entertainment, such as playing a video game or 
viewing a motion picture. 
Referring to FIG. 1, a seating apparatus 10 according to the invention can 
be mounted by a user 12 for use during the playing a video game through a 
computer 14, on for example a stand 16, with associated viewing on a video 
monitor 18 or the like. The user 12 can interact with the computer 14 or 
video game through hand controls 20 in known manner. The apparatus 10 
supplies audio and preferably tactile signals to the user 12, as discussed 
more fully below. The input signals from the computer can be provided 
through a cable 22 to the apparatus 10. 
Preferred embodiments of the present invention makes use of both spatial 
signal processing (the placement of transducers in known spatial 
relationships with respect to the listener), temporal signal processing 
(the selection of the range of frequencies reproduced by each transducer 
in the system), power balancing (the selection of the relative loudness of 
the sounds the listener hears from each transducer), and vibrational 
coupling to create a multi-dimensional (the spatial dimensions, the 
temporal dimension, the power-balancing dimension, and the tactile 
dimension) acoustical audio system with desirable psycho-acoustical 
effects. The system has been designed to produce a sound field optimized 
for perception through the process by which the binaural auditory system 
(human hearing) processes sound, as opposed to being designed to produce a 
certain frequency response at a microphone placed some fixed distance 
on-axis from a speaker in an anechoic environment as in conventional 
loudspeaker performance assessment. The result is an increase in the 
perceived "width" and "depth" of the "sonic image" and an increased the 
"sweet spot" well beyond those perceived with normal stereophonic sound 
reproduction. 
The combining of both spatial signal processing, temporal signal 
processing, and power balancing in the present invention provides some of 
the advantages available through Digital Signal Processing (DSP), and 
allows the realization of many psycho-acoustical effects not available 
through DSP. 
Because the present invention is designed for perception by the binaural 
auditory system, it is appropriate to review this biological system here. 
Binaural hearing is required to physically locate stimuli in the real 
world. There are two basic methods by which the location of a sound source 
is determined by the binaural auditory system. Each is distinct and has an 
effective bandwidth of operation. Firstly, the interaural time difference 
(ITD) in the arrival of a sound wave at each respective ear can be used to 
determine the direction from which the sound emanated. At relatively low 
frequencies, below 1500 Hz, the wavelength of the sound wave is greater 
than the characteristic dimension between the ears (approximately 0.2 m 
for a typical person). Thus, a distinct time delay in the propagation of 
the sound wave can be resolved. While this method of resolving the 
direction can be effective up to 3000 Hz, it has limited accuracy between 
1000 Hz and 3000 Hz as the acoustic wavelength decreases. At frequencies 
greater than 3000 Hz, the primary method of resolving the direction of a 
sound source is based upon the interaural intensity difference (IID). At 
higher frequencies and decreasing acoustic wavelength, sound waves are 
partially blocked by the effective "baffle" created by the head if the 
source is not positioned directly in front of the listener. Thus, 
variations in sound intensity presented at each ear help in discerning the 
location of a source at relatively high frequencies. 
In reverberant, enclosed, sound fields, the sound originating from a source 
will bounce off the walls several times in various directions until it 
decays sufficiently to be inaudible. However, for transient acoustic 
waves, extensive testing has shown that the direction from which a sound 
first arrives is perceived to be the location of the source even if the 
reflected (delayed arriving signal) is larger than the first arriving 
signal (Moore, 1989). 
Oddly enough, the frequency range in which directional information is 
difficult to discern by either ITD or IID is in a range of 1 kHz to 3 kHz 
where the sensitivity of the ear to sound is quite high. Accordingly, a 
single mono sound source placed in front of the listener with an upper 
frequency limit of approximately 3 kHz and will not have a dramatic effect 
on the perceived direction of the sound over the audible range, but can be 
effectively used to "create the center stage". 
At higher frequencies, it is imperative to have both left and right stereo 
signals if stereophonic imaging is desired. In fact, based upon the IID 
method of detecting the position of a sound source, the optimal location 
of the stereophonic transducers producing sound in the approximately 900 
Hz to 16 kHz bandwidth are at opposite sides of the listener to maximize 
the IID. At low frequencies, the acoustic wavelength is so long that a 
listener cannot accurately resolve the direction of the source (because 
the sound heard at either ear is nearly in phase), so a sub-woofer (0 to 
250 Hz bandwidth) can be placed in any position relative to the user to 
economically reproduce the low-frequency component of the sound (which 
usually requires the most power and produces the most driver cone 
excursion). Finally, a single mono high frequency device (producing 
frequencies from approximately 4-6 kHz to &gt;20 kHz) can be located near the 
rear of the listener or centrally overhead to achieve the effect of 
greater reverberation. The pinna (outer ear) serves to diminish the sound 
by virtue of reflection and diffraction at high frequencies when the sound 
wave is presented from behind. Acoustic waves reflected in a reverberant 
field also impinge the ear at reduced intensities than that of the 
original wave. Thus, placing a higher frequency driver at the rear of the 
listener can achieve the psycho-acoustical impact of a more "live" 
acoustic field as opposed to the more complex use of full-bandwidth 
transducers and signal processing to achieve the same desired effect. 
Traditional acoustical priorities such as low distortion and adequate 
frequency response, together with new objectives involving 
psycho-acoustical qualities such as "spatiality" have been taken into 
account by the design of one embodiment of the multi-dimensional 
acoustical audio system set forth herein. Conventional audio speaker 
performance specifications lose meaning here because the sound system 
provided by this invention is designed to be perceived through the 
binaural auditory system, not a microphone positioned at a fixed distance 
from a speaker mounted in a baffle. Quality transduction devices are used 
in this system to minimize distortion. Within the present invention, the 
relative sensitivity of each transducer is not as important as is the 
location of each device relative to the listener, coupled with the 
associated temporal filtering which is unique to the position of the 
device relative to the listener. 
In one embodiment according to the invention, the apparatus comprises a 
collapsible portable chair or seat with an integral audio system. While in 
collapsed form, all drivers and amplifiers of the audio system are 
internal to the unit. When in use, some components of the audio system 
remain internal to the chair, and some are deployed in a fixed spatial 
relationship to the seat (and the listener seated there). 
In addition to the placement of the transducers in the system, there are 
certain aspects of the mounting of the transducers and the design of the 
individual transducer enclosures which provide key improvements in the 
quality of the perceived sound field. The side transducers are 
preferentially oriented vertically (with their radiating surfaces parallel 
to the horizontal plane), and their enclosures preferentially include 
acoustic reflectors suspended in front of the transducers, to give a more 
desirable acoustic dispersion pattern across the range of frequencies 
produced by the transducer. This circularly symmetric reflector ensures 
that sound emanates with equal intensity in all directions in the 
horizontal plane. This circularly symmetric pattern may be combined with 
placement of a reflecting surface on the opposite side of the side sound 
sources from the listener. This spreads out the apparent side sources from 
the point of view of the listener, because sound energy may be received 
from all over the reflective surface. The apparent spreading of the source 
can result in an improved psycho-acoustical effect. 
Referring to FIG. 2, the apparatus 10 is preferably constructed as a 
portable, collapsible seat 24 with integral and attached audio components. 
The seat 24 includes a base 26 connected to a back 28 through a hinge 
assembly 30. The base 26 is constructed for placement on the floor, but 
can also be mounted on a pedestal 32 for raised seating more in the manner 
of a chair. The seating area 34 of the base 26 and the support area 36 of 
the seat back 28 can be equipped with cushioned surfaces, such as by foam 
or rubberized pads, to provide comfortable seating to a user. 
The system preferentially includes at least one central audio loudspeaker 
38 placed substantially in front of the user. The central audio 
loudspeaker 38 is preferably positioned forward of the seating area 34 
near the front edge 40 of the seat base 26, facing upwardly, and may in 
some embodiments be placed separately from the seat 24 closer to the video 
screen being viewed. The central audio loudspeaker 38 preferably has an 
input filtered to range in frequency from substantially 150 Hz to no more 
than 10 kHz. In a preferred embodiment, the maximum input frequency to the 
central audio loudspeaker 38 is limited to 6 kHz. The central audio 
loudspeaker 38 can be any of a variety of loudspeakers capable of 
performing in the frequency range specified but is preferably selected to 
have an optimal sensitivity and performance in the above input range. 
The embodiment for immersive observation further includes a left audio 
loudspeaker 42 placed directly to the listeners' left when seated, and a 
right audio loudspeaker 44 placed in directly to the listener's right. The 
left audio loudspeaker 42 and the right audio loudspeaker 44 should be 
spaced far enough from the listener's ears when seated so that the 
distance from the listener's head to each of these loudspeakers 42, 44 is 
large compared to the normal amount that the listener's head might move 
forward, backward, and from side to side during the normal playing of a 
video game or watching of a movie. 
While it is preferred that the left audio loudspeaker 42 and the right 
audio loudspeaker 44 be located directly to the sides of the observer, it 
is within the scope of the invention that the loudspeakers may be forward 
or rearward of these exact positions, but preferably these speakers are 
symmetrically placed, at positions no more than 50 degrees off to the 
front or rear of an imaginary line passing through the listener's ears 
when seated. 
The left audio loudspeaker 42 and the right audio loudspeaker 44 can each 
be mounted in a wing 46 formed on either side of the seat base 26. The 
seat back 28 can provide mating wings 48 to overlay the base wings 46 when 
the base 26 and back 28 are engaged in a closed position. 
According to the invention, the left audio loudspeaker 42 and the right 
audio loudspeaker 44 each have an input preferably filtered to range in 
frequency from substantially 900 Hz to at least substantially 12 kHz, in 
order to produce the desired psycho-acoustical effect. The frequency range 
of the left audio loudspeaker 42 and the right audio loudspeaker 44 can 
extend beyond 16 kHz. The left and right audio loudspeakers 42, 44 may be 
constructed using of a variety of drivers capable of performing in the 
frequency range specified but are preferably made with drivers selected to 
have an optimal sensitivity and performance in the specified input range. 
In combination with the left audio loudspeaker 42 and the right audio 
loudspeaker 44, the central audio loudspeaker 38 creates a central image 
with greater perceived "depth" to the sound field. 
The embodiment for immersive observation preferably further comprises at 
least one sub-woofer audio loudspeaker (not shown in FIG. 2) having at 
least one low pass filtered input having an upper cutoff frequency 
preferably below 100 Hz. The sub-woofer audio loudspeaker may be placed 
anywhere, but is preferentially mounted inside the back section 28 of the 
seat 24. 
A preferred embodiment of the immersive sound system further includes a 
high frequency device 50 or transducer with a frequency bandwidth 
extending from approximately 4-6 kHz, preferably through the upper 
frequency limit of human hearing (15-20 kHz). The amplifier for the high 
frequency device 50 may be a dedicated amplifier or part of a multichannel 
amplifier, and is preferably equipped to sum the two signal inputs from a 
typical stereo audio source to mono prior to amplification. 
The high frequency device 50 is preferably mounted to the rear of the 
listener, near or above the level of the listener's ears, and vertically 
higher than the left and right audio loudspeakers 42, 44. The high 
frequency device 50 may be constructed using a variety of transducers 
capable of providing high quality sound in the specified range. 
Referring to FIGS. 3 and 4, the back can be constructed by the merger of a 
rear section 52 (FIG. 3) and a front section 54 (FIG. 4). The sub-woofer 
loudspeaker 56 is preferably mounted in a dual-tuned cavity design. The 
back side of the sub-woofer loudspeaker drives a lower-frequency tuned 
cavity 58, while the front side of said driver 56 drives a 
higher-frequency tuned cavity 60. Acoustic energy from the tuned cavities 
58, 60 is ported to the outside environment for the listener through ports 
62 respectively. The tuned cavities 58, 60 preferably have their resonant 
frequencies so aligned that the lower 3 dB point of the higher-frequency 
tuned cavity 60 is coincident in frequency with the upper 3 dB point of 
the lower-frequency tuned cavity 58. 
The described positioning of the subwoofer 56 provides two advantages. 
First, the preferred position of the axis of motion of the subwoofer 56 
transverse to the support surface 36 of the seat back 28 (FIG. 2) places 
tactile vibrations from the subwoofer 56 adjacent the lower lumbar region 
of a user seated in the apparatus. Secondly, the porting of the subwoofer 
back waves along the sides of the seat back 28 produces the signal 
proximate the users's ears for enhanced efficiency in delivery of the bass 
signals. 
The sub-woofer audio loudspeaker 56 can be driven by an output channel of a 
separate amplifier that combines the two channel input from the audio 
source. Alternatively, the sub-woofer audio loudspeaker 56 can be driven 
by one of the outputs of a multichannel amplifier that processes the two 
channel input from the audio source. 
The high frequency loudspeaker 50 can be mounted along a top side 64 of the 
seat back 28 for positioning above the left and right loudspeakers 42, 44 
(FIG. 2) and proximate the rear of the user's head, as discussed above. 
The seat back 28 preferably includes a lower extension 66 with lateral 
hinge posts 68 for pivotally connecting to the seat base 26. The front and 
rear sections 52, 54 of the seat back 28 can be injection molded and 
secured together with peripheral snap mounts 70 and screw ports 72. 
Referring to FIGS. 5 and 6 together, the seat base 26 can be formed by the 
merger of a lower section 74 (FIG. 5) and an upper section 76 (FIG. 6), 
which bears the seating area 34 (see FIG. 2). The rear waves of the 
central audio loudspeaker and the left and right loudspeakers can be 
ported to the sides 78 of the seat base through a chamber 80 defined in 
the seat base sections. The upper section of the seat base can provide 
grilled apertures 82 for the front waves of the central loudspeaker and 
the left and right loudspeakers. 
In order increase the acoustic efficiency and further increase the 
homogeneity of the radiation pattern, each grilled aperture 82 can provide 
a circularly symmetric, preferably hemispherical acoustic reflector 84 
thereby placed in front of each driver, external to the speaker enclosure 
26. The circularly symmetric acoustic reflector serves two functions (in 
addition to being aesthetically pleasing). First, the acoustic reflector 
concentrates more of the sound energy at the level in the room where 
listener's ears are likely to be, and reduces the acoustic energy at the 
ceiling or floor level. This distribution increases the efficiency of the 
system. Second, the reflector may be shaped to reduce the vertical 
inhomogeneities in the sound field in the vertical region of the room 
where listener's ears are likely to be. As mentioned in the summary of the 
invention, the circularly symmetric radiation pattern of the left and 
right loudspeakers, may be combined with their proximity to acoustic 
reflectors, resulting in a diffusing effect on the localizability of the 
left and right loudspeakers, adding to the psycho-acoustical quality of 
the listening experience. Because the ear differentiates between first 
arrival and echoes, it is important to keep the left and right 
loudspeakers close to reflectors if the defusing effect is to be 
optimized. This is because when the speakers are close to the reflectors, 
the amplitude of the first echo (from the reflector next to the speaker) 
is so close the amplitude of the sound directly from the speaker, and the 
delay between the first arrival and the first echo is so short, that the 
human auditory system perceives the two as one (diffused) source. In many 
cases, this can add to realism, because many real-life sources of 
high-frequency sound (such as a symbol), are much larger physically (and 
therefore less spatially localizable by human hearing) than the tweeter of 
a typical loudspeaker. 
The upper and lower sections of the seat base can provide a series of 
support ribs 86 on two rear extensions 88 for engaging and securing the 
hinge posts 68 of the seat back (FIGS. 3 and 4). The lower section 
provides, between the extensions, an abutment surface 90 for engaging the 
lower extension of the seat back to limit the opening pivot of the seat 
back to its final upright position, as shown in FIG. 2. 
Referring to FIG. 7, the seat assembly is preferably collapsible to a 
closed configuration suitable for protective storage of the loudspeakers 
during transport. The lower extension of the seat back can provide an 
opening 92 to form a carrying handle. To secure the seat assembly in 
either the open position for use, as shown in FIGS. 1 and 2 or the 
collapsed, storage and transport position shown in FIG. 7, the apparatus 
can provide a latch mechanism actuated by push buttons 94, one on each 
side of the seat base. 
Referring to FIG. 8, the button 94 can be connected to a latch bar 96 
terminating in a latch head 98. The latch head can interface with a cam 
arm 100 on the hinge post to prevent relative rotation of the seat back 
and the seat base. The seat back and the seat base, illustrated in the 
open position are thus prevented from being closed. 
The latch head and its actuating button can be urged to the latching 
position shown by a spring tab 102 extending from the seat base. The 
spring tab can be plastic molded integrally with the seat base and 
positioned to bias the latch bar through pins 104 to the latched position. 
To release the latch head from the locked position and permit rotation of 
the hinge post, the button can be urged against the resistance of the 
spring tab. A similar assembly can exist on the opposite side of the seat 
base, and unlatching occurs in such a case by simultaneous depression of 
the latch buttons. The seat back can be biased to begin its collapse upon 
depression of the latch buttons by a resistive compression of a resilient 
pad 106 at the rear of the seat base (FIG. 7) for resistive engagement 
with the lower extension of the seat back. 
The opposite side of the latch cam of the hinge post can also be latched by 
the latch head when the seat assembly is collapsed. The collapsed seat 
assembly can be biased to open when the latch buttons are depressed by the 
resistive compression of the seat pads (FIG. 2). 
The audio system for providing driving signals to the loudspeakers includes 
an audio generating source for generating a plurality of audio signals and 
may be a gaming or other type computer with CD player, film soundtrack, 
VCR player or tape deck. The audio source is fed to signal processing 
electronics which can include preamplifiers and crossover networks to 
amplify the signal and use either active or passive crossover networks to 
separate the frequencies but preferably with predetermined overlaps for 
the different loudspeakers. The crossover network can produce two or more 
channels in the frequency range from substantially 20 Hz to 20 kHz for the 
left, right, center, rear, and sub-woofer audio loudspeakers, and an 
electromechanical vibration transducer, if one is used. 
The signals generated by the signal processing electronics are preferably 
amplified by an amplifier system utilizing separate amplifiers to drive 
the spatially and spectrally distinct loudspeakers in the system. The 
amplifier system and crossover electronics may be built into the seat, or 
housed in a separate enclosure. 
In a preferred embodiment utilizing a separate amplifier for each 
transducer, the amplifier system also includes transducer-specific limiter 
circuitry to ensure that the acoustic signals produced by each transducer 
are within an amplitude range considered safe for human hearing. 
A headphone jack can be included to facilitate use while causing less 
disturbance in a surrounding area. In a preferred embodiment, plugging in 
headphones to the headphone jack substantially silences all but the lowest 
frequencies produced by the audio and vibrational transducers of the 
apparatus. Low-frequency signals produced by the transducers are left 
undiminished by the use of headphones, in order that the user may still 
experience the tactile portion of the virtual reality experience. 
The novel positioning and geometric construction (spatial signal 
processing) and operating frequency bandwidth (temporal signal processing) 
of each loudspeaker contributes to the creation of a sound field with a 
greater perceived sonic width and depth than conventional loudspeaker 
systems and to the creation of an expanded "sweet spot" within the 
(enclosure) seated environment. 
The electronic signals sent to central, subwoofer and high frequency 
drivers are preferably all mono, as opposed to stereo. The only stereo 
signals of the preferred embodiment are sent to left and right drivers. 
The left and right stereo signals sent to left and right transducers are 
required by the binaural auditory system to effectively "locate" or 
"position" the stimuli audibly. 
According to the invention, the central loudspeaker positioned at "center 
stage" can be supplied with a mono signal between 150 Hz and 3000 Hz, 
which fills the listening environment with low to mid frequency sound 
waves without deteriorating the stereophonic image created by the left 
audio loudspeaker 16 and the right audio loudspeaker 17. 
The optimization of the sound field through the combination of placement 
and frequency range selection is detailed in Applicant's U.S. Pat. No. 
5,764,777, which is incorporated by reference herein. 
The foregoing discussion should be understood as illustrative and should 
not be considered to be limiting in any sense. While this invention has 
been particularly shown and described with references to preferred 
embodiments thereof, it will be understood by those skilled in the art 
that various changes in form and details may be made therein without 
departing from the spirit and scope of the invention as defined by the 
claims.