Abstract:
A SoundNet is a process for synthesizing sonic environments for use in Virtual Environment applications, computer games, Internet web pages, film and television productions. A sonic environment is a collection of spatially located sounds describing some scenario such as a city street for example. SoundNet provides a process for generating such an environment that has the following properties: a compact representation, stochastically correct behavior, dynamically varying behavior along application defined parameters, temporally unbounded and non-repeating, and facilitates automatic generation of the representation.

Description:
FIELD OF THE INVENTION 
     The present invention relates to computer sound. More specifically to a sonic environment. Still more particularly to a sonic environment having behavioral modification. 
     BACKGROUND OF THE INVENTION 
     In the past, the main focus in computer sound has been on computer music and sound synthesis. Both are interesting problems, but there is an unfulfilled need for tools to create whole sonic environments. A sonic environment is a collection of spatially located sounds describing some scenario. For example, while a sonic forest environment may include a bird, wind, water, animal and human sounds it is very difficult, using current tools, to create such an environment because there is no easy way to orchestrate the sounds. 
     There are two ways to create such a sonic environment, the first is to obtain an actual recording of a forest and play it back. Unfortunately this technique is very storage intensive, a two-minute digital recording at CD quality will require 20 Mbytes of storage. It is also very difficult to make any changes to the sounds once they are recorded and it is impossible to modify the behavior of the sounds dynamically during playback because the representation is not parameterized. Finally, a digital recording is temporally bounded while the application may not be. When an application is temporally bounded it lasts for a finite amount of time. For example, a walk through of the virtual environment will last as long as the user wishes and the application may run out of recorded material yielding no sound. The solution to this would be to loop the recording so that when it ends, playing back again from the beginning. However this solution is noticeable and the environment does not seem realistic. 
     The second way to create a sonic environment is to use a scripting technique such as a MIDI sequencer to initiate the playing of individual recordings of each of the sound elements comprising the environment, such as a bird call, wind blowing etc. This solves some of the problems mentioned earlier because such a representation is not storage intensive, and a MIDI script can be modified. Other problems, however, persist. While it may be possible to dynamically modify the playback behavior using MIDI control messages such as pitch bend and modulation, this mechanism is intended for musical performance and does not provide the capability to dynamically change the behavior of the environment in a meaningful way. A MIDI script is temporally bounded so that the script may run out before the application is done. Creating the script in the first place is a very tedious task. 
     Existing techniques include digital recordings and scripting techniques such as MIDI sequences. A digital recording of a sonic environment can be made and played back by the application. Such a representation only exhibits a compact representation. Scripting techniques may be used to orchestrate the playback of the sounds comprising a sonic environment. Scripting techniques do not however exhibit compact representations, stochastically correct behavior, nor dynamically varying behavior. Scripting techniques only provide a limited facility for generation of the representation. 
     The inherent draw back of current representations is that they are literal: the representation is a specification for a single behavior of the sonic environment over a limited period of time. For example we can model a city street by creating a MIDI script that lasts for two minutes and specifies that an ambulance sound should commence one minute into the script and play for thirty seconds. 
     There is an unfulfilled need for tools to create entire sonic environments. 
     SUMMARY OF THE INVENTION 
     A sonic environment is a collection of spatially located sounds describing some scenario. A representation of a sonic environment should have a compact representation. A sonic environment should exhibit well-defined stochastic behavior, and should be temporally unbounded. The sonic environment behavior should be dynamically modifiable through intuitive, application defined parameters. Finally it should lend itself to automatic generation. 
     The present invention, deemed SoundNet, provides a mechanism for modeling sonic environments that exhibit characteristics that are not possible using current techniques. SoundNet provides a mechanism for expressing sound environments based on programmed behavior of sounds as well as stochastically varying behavior. 
     SoundNet is made up of SoundNets, which are not temporally bounded so that an environment can be generated indefinitely without the need to resort to looping behavior. SoundNets are a compact representation, which is an important feature for network-based applications like the Internet. SoundNets can be dynamically controlled to modify their behavior at runtime based on application-defined criteria. Finally SoundNets can be automatically generated. This creates a slew of new possibilities in sound research. 
     A SoundNet is a process for synthesizing sonic environments for use in Virtual Environment applications, computer games, Internet web pages, film and television productions. A sonic environment is a collection of spatially located sounds describing some scenario such as a city street for example. SoundNet provides a process for generating such an environment that has the following properties: a compact representation, stochastically correct behavior, dynamically varying behavior along application defined parameters, temporally unbounded and non-repeating, and facilitates automatic generation of the representation. 
     SoundNets, on the other hand, are behavioral representations. The representation is a model of how sounds generally act in a given environment. A similar example in SoundNet would model a city street by specifying that an ambulance sound occurs on average once a day, usually in the evening. This is a much more powerful representation because it is not time limited, it is non-repeating, it is parameterized and is encapsulates the stochastic properties of the sounds in the environment. 
    
    
     BRIEF DESCRIPTIONS OF THE DRAWINGS 
     A more complete appreciation of the invention and many of the attendant advantages thereof will become better understood when referring to the accompanying drawings wherein: 
     FIG. 1 is an example of the present invention. 
     FIG. 2 is a refinement of the present invention in FIG.  1 . 
     FIG. 3 is a further refinement of the present invention in FIG.  1  and FIG.  2 . 
     FIG. 4 is a flowchart of the present invention Counter node. 
     FIG. 5 is a flowchart of the present invention Delay node. 
     FIG. 6 is a flowchart of the present invention Probability node. 
     FIG. 7 is a flowchart of the present invention Signal node. 
     FIG. 8 is a flowchart of the present invention Broadcast node. 
     FIG. 9 is a flowchart of the present invention Gate node. 
     FIG. 10 is a flowchart of the present invention PlaySound node. 
     FIG. 11 is a flowchart of the present invention PlayScript node. 
     FIG. 12 is a flowchart of the present invention ModifySound node. 
     FIG. 13 is a flowchart of the present invention MoveSound node. 
     FIG. 14 is a flowchart of the present invention Network node. 
     FIG. 15 is a flowchart of the present invention Generator node. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     SoundNet represents a sonic environment as a network of interconnected nodes. Sonic environments may be created by using synthetic sounds. The behavior of the sonic environment is driven by tokens that propagate through the network. A network node becomes active once it is visited by a token. Once active, a node performs a certain function and may or may not propagate the token forward. The preferred network is a high level petri network, a technique used for modeling complex concurrent systems. 
     SoundNet defines a set of standard nodes required for generating sonic environments. Nodes are parameterized so that their behavior can exhibit variations based on a random distribution or external parameters such as time of day, time of year, listener location or anything the designer of the environment may want. 
     FIG. 1 is illustrates the present invention creating a birdcall of a Crow chirping. Generator node  100  produces tokens. Value node  103  specifies the rate at which generator node  100  produces tokens. In this example, value node  103  specifies a rate of 10 to 30 seconds. The actual value returned from value node  103  is based on a random distribution and will be between 10 to 30 seconds. 
     After generator node  100  receives a value from node  103 , generator node  100  then creates a token after the time vale created from value node  103  has elapsed. Generator node  100  then passes a token on to play sound node  101 . 
     The token passed from generator node  100  will cause play sound node  101  to play the birdcall of a Crow and then forward the token to counter node  102 . 
     Value node  104  will create a value between 2 and 4 and pass it to counter node  102 . Counter node  102  receives the token from play sound  101 . Counter node  102  will decrement the value received from value node  104  and if the value is non-zero then counter node  102  will pass the token through edge  105  to play sound node  101  to repeat the process. When counter  102  becomes zero, the token will follow edge  106  and the token will expire. 
     The process will continue with the value of counter node  102  being reset to a value between 2 and 4 based on the random distribution returned by value node  104 . This simple soundnet will produce a succession of 2 to 4 Crow&#39;s birdcalls every 10 to 30 seconds. 
     A listener attending to the sound produced by the SoundNet in FIG. 1 will observe a Crow&#39;s birdcall occurring at random times and with random durations. The birdcall will not appear to be repeating as would be the case with a digital recording of the sound because of the randomness of the occurrence rate and duration of the call. A soundnet birdcall will sound natural because the randomness introduced will exhibit correct statistical behavior of a Crow&#39;s birdcall heard in nature. 
     The SoundNet in FIG. 1 may easily be modified to better simulate bird sounds in nature by providing the listener with the impression of a number of birds in varying locations, as shown in FIG.  2 . 
     FIG. 2 is a refinement of the present invention in FIG.  1 . The SoundNet in FIG. 1 was modified by adding move sound node  207 , value node  208 , and modifying value node  203 . 
     The operation of the SoundNet in FIG. 2 is as follows. Generator node  200  produces tokens at a rate of one every 5 to 10 seconds based on a random distribution returned by value node  203 . A generated token will activate move sound node  207 . Move sound node  207  will modify the location of the sound played by play sound node  201 . The location of the sound played by play sound node  201  will be determined by value node  208 . 
     Value node  208  provides a three-component vector of random values based on the distribution in value node  208 . Move sound node  207  will forward the token to play sound node  201 . Play sound node  201  will play the sound of a birdcall at the specified location and then forward the token to counter node  202 . 
     Counter node  202  receives a counter value from value node  204  which will be between 2 and 4 in this example. Counter node  202  will then decrement the counter and, if non-zero, will output the token through edge  205  returning it to play sound node  201 . When counter node  202  becomes zero, the token will follow edge  206  and expire. 
     Once the token expires, counter node  202  will then be reset with a value between 2 and 4 based on the random distribution returned by value node  204 . This soundnet, with variables used in this example, will produce a succession of 2 to 4 bird calls every 5 to 10 seconds at a location within a space which is bounded in x, y and z by −100 and 100 created by value node  208 . 
     A listener attending to the sound produced by the SoundNet in FIG. 2 will observe birdcalls in a more rapid succession than that exhibited by the SoundNet in FIG.  1 . In FIG. 2 the bird calls will occur in varying locations so that the listener will perceive the calls as coming from different birds at varying locations inside the sound field. In a natural environment, the listener would normally hear a variety of birdcalls corresponding to the different species of birds present in the environment. 
     The soundnet in FIG. 2 may be modified to create multiple birdcalls. FIG. 3 is a further refinement of the present invention shown in FIG.  1  and FIG. 2, and the SoundNet in FIG. 3 includes three separate paths in the process, each path in the process activates a different birdcall. 
     Generator node  300  starts the process by generating a token at a rate of one every 5 to 10 seconds depending on the value returned by value node  301 . A token is generated by generator node  300  and the token is propagated to probability node  302 . 
     Probability node  302  receives the token from node generator  300  and passes the token to either move sound node  303 , move sound node  305 , or move sound node  310 , depending on the probability assigned to each of the nodes. 
     In this example move sound node  303  has an associated probability value of 0.6 shown by edge  306 . Move sound node  205  has a probability of 0.3 shown by edge  307 , and move sound node  310  has a probability of 0.1 as shown by edge  309 . Therefore, on average 6 out of every 10 incoming tokens will be propagated by probability node  302  to move sound node  303 . Three out of each 10 tokens will be propagated to move sound node  305 , and 1 out of every 10 tokens will be propagated to move sound node  310 . 
     The process of the soundnet past probability node  302  is similar to the process in FIG.  2 . Play sound nodes  313 ,  315  and  317  play the birdcalls of a Crow, a Robin and a Blue Jay, respectively. Value nodes  319 ,  321  and  323  return different value ranges based on the expected behavior of the birdcall of the three bird species, Crow, Robin, and Blue Jay, being played. 
     Value node  319  will return a distribution value between 2 and 4 for counter node  318 . Value node  321  will return a distribution value between 1 and 3 for counter node  320 . Value node  323  will return a distribution value between 1 and 5 for counter node  322 . 
     Counter node  318  will decrement the distribution value and continue to pass the token to play sound node  313  as long as the distribution value is non-zero. Once the distribution value is zero, counter node  318  will pass the token on to expire  324 . 
     Counter node  320  will decrement the distribution value and continue to pass the token to play sound node  315  as long as the distribution value is non-zero. Once the distribution value is zero, counter node  320  will pass the token on to expire  325 . 
     Counter node  322  will decrement the distribution value and continue to pass the token to play sound node  317  as long as the distribution value is non-zero. Once the distribution value is zero, counter node  322  will pass the token on to expire  326 . 
     A listener attending to the sound produced by the SoundNet in FIG. 3 will observe three different birdcalls at varying intervals, locations, and rates of occurrence. The listener will hear a predominance of Crows, some Robins, and less frequently, Blue Jays, based on the probabilities associated with probability node  302 . The pattern of birdcalls will sound natural and will not appear to be repeating. Furthermore the sound produced by this SoundNet may be played indefinitely without repetition so that the environment will sound natural for as long as deemed necessary by the application. 
     Producing a similar sonic environment utilizing a digital recording or sequencing scheme would not be possible since at some point, looping would be necessary because the representations are temporally bounded. 
     The previous example can be further refined to include other animal calls found in the forest as well as natural sounds such as wind. The time of day and year could be taken into account so that a selection of sound is played which is appropriate for that time of day and year. 
     The following are explanations of the present invention nodes comprising components of the soundnet network. The novelty of the SoundNet technique is its use of High Level Petri nets to represent sonic environments, and its definition of appropriate nodes. The following is a description of the constituent elements comprising a SoundNet network. 
     Value Nodes 
     The prototype node in SoundNet encompasses a behavior and a set of portals that can receive values one for each parameter of the node. These values, in turn, affect the behavior of the node. The concept of a generic value node  1 is a powerful construct allowing SoundNet to exhibit interesting behavior. 
     A Value node can be of any type, which may be a constant numeric value, one of many random distributions, a boolean value, an ordered sequence, a date and time, an interpolated value, or an external parameter. Upon evaluation a value node returns a value based on its type. 
     A constant numeric value node simply returns it&#39;s numeric value. A random distribution node returns a numeric value between a user specified minimum and maximum value based on a random distribution. A boolean value node returns true or false based on a logical expression. A date and time node returns the current date and time. An external parameter node returns a numeric value set by the application program. An ordered sequence node returns the next value of a sequence of specified values, upon reaching the last value of the sequence, the sequence is started from the beginning. An interpolated value node returns an interpolated value which can be specified as a linear interpolation, a straight line between two values, or a higher-level interpolation, a spline. 
     Routing Nodes 
     Routing nodes control the propagation of a token through the SoundNet network. Routing nodes are essentially the control mechanism used in implementing a behavior for the soundnet. Routing nodes consist of the following nodes: a counter node, a delay node, a probability node, a signal node, a broadcast node, and a gate node. 
     FIG. 4 is a flowchart of the present invention Counter node. A Counter node decrements an internal counter and propagates a token to one of its two outputs based on the value of the counter. 
     The process starts at step  400 , which receives the incoming token. Decision step  402  then determines if a token has been received. If a token is not present then step  404  end the process for this node. If a token is present then step  406  decrements the counter value. Decision step  408  then determines if the counter value is zero or non-zero. Step  410  receives the token if the counter value is non-zero and passes the token to the node connected to the “true” edge of the node. Step  412  receives the token if the counter value is zero and passes the token to the “false” edge of the node. 
     FIG. 5 is a flowchart of the present invention delay node. A delay node holds an incoming token for a specified amount of time before propagating it to its output. Step  500  reads a token that was previously stored in this node. Decision step  502  determines if a token is present and if so passes the process to step  504 , if a token has not been received from step  500  then the process passes to step  512 . 
     Step  504  obtains the current time and determines the elapsed time. The elapsed time is determined by subtracting the recorded time of the arrival of the token from the current time. Step  504  then passes the process on to decision step  506 . 
     Decision step  506  determines if the elapsed time is greater then or equal to the delay time, which is the amount of time that the token must be held by this node. If the time elapsed is equal to or greater than the delay time then process step  510  sends the token on to the next node and the process continues to step  512 . If the time elapsed is less than the delay time then process step  508  holds the token and the process continues to step  512 . 
     Step  512  receives a token. Decision step  514  receives the token and determines if the a token is present, if a token is present then the process passes on to step  516 . If a token is not stored in this node then the process ends for this node in step  518 . Step  516  stores the token and records the date the token was received. 
     FIG. 6 is a flowchart of the present invention probability node. A probability node propagates an input token to one of its outputs based on the probabilities assigned to each output connected to the node. 
     Step  600  receives a token. Decision step  602  determines if a token is present. If a token is present in decision step  602  then the process is passed on to step  604 . If a token is not present in decision step  602  then the process ends for this node in step  606 . 
     Step  604  then generates a random number between zero and one and passes the process onto step  608 . For each output the process passes on to step  610  to determine if the probability assigned to the output being evaluated is greater then or equal to the random number, if true then the process passes on to step  612  to send the token to the node associated with the output. If false, then the process passes back to step  608  to evaluate the next output. 
     FIG. 7 is a flowchart of the present invention Signal node. A Signal node holds an input token until it has received a signal to release the token. The process starts with step  700 , which receives a token, stores it in the node and passes the process on to step  702 . Decision step  702  determines if a token is stored in this node. If a token is stored in this node then decision step  702  passes the process on to decision step  706 . If a token is not stored in this node then decision step  702  passes the process on to step  704  which ends processing for this node. 
     Decision step  706  passes the process on to step  708  if a signal is raised to release the token. A signal is raised by a process external to the SoundNet such as a user application. Step  708  then passes the token to an output. Decision step  706  passes the process on to step  710  if a signal is not raised to release the token. Step  710  ends processing for this node. 
     FIG. 8 is a flowchart of the present invention broadcast node. A broadcast node generates one token for each output connected to the broadcast node upon receiving a token. The process starts at step  800 . Step  800  then passes the process on to decision step  810 . Decision step  810  then passes the process on to step  812  if a token is present. Decision step  810  passes the process on to step  814  if a token is not present. 
     Step  812  passes the token to each output of the broadcast node. Step  814  ends the process for this node. 
     FIG. 9 is a flowchart of the present invention gate node. A Gate node propagates a token while its boolean input evaluates to true. The process starts at step  900  to receive a token. Step  900  then passes the process to step  904  if a token is stored in this node. Step  902  passes the process on to step  906  if a token is not stored in this node. Step  906  ends the process for this node. 
     Process step  904  then evaluates input boolean expression B and decision step  908  passes the process on to step  910  if boolean expression B is true, or passes the process on to step  912  if boolean expression B is false. Step  910  passes the token to the output. Step  912  holds the token in this node. 
     Sound Control Nodes 
     Sound control nodes control the behavior of sound by starting, stopping and modifying sounds. They utilize a  3 D audio subsystem for playing, modifying, and positioning sounds. Sound control nodes consist of the following: a PlaySound node, a PlayScript node, a ModifySound node, and a MoveSound node. 
     FIG. 10 is a flowchart of the present invention PlaySound node. A PlaySound node commences the playback of a sound upon receiving a token. The token can be released immediately or after the playback has been completed depending on the characteristics of the node. Step  1000  begins the process of the PlaySound node by reading the token previously stored in the node. Step  1000  then passes the process to step  1002 . Step  1002  determines if a token is present and if so passes the process to step  1004 , otherwise it passes the process to step  1008 . Step  1004  determines if a sound is currently playing and if so passes the process to step  1006  otherwise it passes the process to step  1008 . Step  1006  holds the token at this node. Step  1008  receives a token and passes the process on to step  1010 . Step  1010  then passes the process on to step  1014  if a token is present or passes the process on to step  1012  if a token is not present. Step  1012  ends the process for this node. 
     Step  1014  makes a function call to start the sound and passes the process on to decision step  1016 . Decision step  1016  passes the process on to step  1018  if the token is to be released immediately. Step  1018  then passes the token to the output. 
     Decision step  1016  passes the token to step  1006  if the token is not to be released immediately. Step  1006  holds the token at this node. 
     FIG. 11 is a flowchart of the present invention PlayScript node. A PlayScript node commences the playback of a sound script upon receiving a token. A script is a set of time-stamped events for starting, stopping and modifying sounds. The process starts at step  1100  which reads the token previously stored in the node. Step  1100  then passes the process to step  1102 . Step  1102  which determines if a token is present and if so passes the process to step  1104 , otherwise it passes the process to step  1108 . Step  1104  determines if a sound is currently playing and if so passes the process to step  1106  otherwise it passes the process to step  1108 . Step  1106  holds the token at this node. Step  1108  receives a token and passes the process on to decision step  1110 . Decision step  1110  passes the process on to step  1114  if a token is present, or onto step  1112  if a token is not present. Step  1112  ends the process for this node. 
     Step  1114  calls a function to start the script routine to play the sound and then passes the process on to decision step  1116 . Decision step  1116  then passes the process on to step  1118  which passes the token to the output, if the token is to be released immediately. If the token is not to be released immediately then decision step  1116  passes the process on to step  1106  which holds the token at this node. 
     Step  1112  passes the process on to step  1116  to hold the token if the script is playing. If the script is not playing then decision step  1112  passes the process on to step  1114  to pass the token to the output. 
     FIG. 12 is a flowchart of the present invention ModifySound node. A ModifySound node modifies a predetermined parameter value associated with a sound. Sound parameters control the sonic quality of a playing sound such as the volume, pitch, modulation etc. The ModifySound node is associated with a specific sound source and parameter value. The parameter value is determined by a Value node attached to the ModifySound node. 
     The process of the ModifySound node starts with step  1200  which receives a node and passes the process on to decision step  1202  to determine if a token is present. If a token is not present then decision step  1202  passes the process on to step  1204  which ends the processing for this node. 
     Decision step  1202  passes the token on to step  1206  if a token is present. Step  1206  queries value node attached to the ModifySound node for a parameter value and then passes the process on to step  1208 . Step  1208  then starts a audio routine, SetParameter, which supplies the parameter name and the new value. Step  1208  then passes to step  1210 . Step  1210  then passes the process to the output. 
     FIG. 13 is a flowchart of the present invention MoveSound node. A MoveSound node moves a sound to a location in three dimensional,  3 D, space based on the value of three input parameters to the node. The process starts with step  1300  receiving a token and passing the process on to decision step  1302 . Step  1302  then passes the process on to step  1306  if a token is present. If a token is not present then step  1302  passes the process on to step  1304 . Step  1304  ends processing for this node. 
     Step  1306  queries value attached to the MoveSound node for a three component vector specifying a new position and then passes the process on to step  1308 . Step  1308  invokes an audio routine, SetPosition, supplying the new position. Step  1308  then passes the process on to step  1310  which passes the token to the output. 
     The Network Node 
     The Network node is the top-level node in any SoundNet. A Network node provides access to the Soundnet network and controls its execution. The traversal of tokens in the SoundNet occurs synchronously at regular intervals. The Network node utilizes a clock signal to update the network at a specified rate. Upon each clock signal, the Network node traverses all the outputs in the SoundNet and calls each output&#39;s Update routine. This routine checks for tokens arriving at the input and upon arrival delivers the token to its output node. The Output node also checks the token for expiration. Users of the SoundNet network control the execution of the network through the Network node. 
     FIG. 14 is a flowchart of the present invention Network node. The process starts at step  1400  where an input clock signal is received. Step  1400  passes the process on to step  1402  which determines each output in the network and passes the process on to step  1404  for each output in the network. Step  1404  then invokes a routine to update each token, Update routine. 
     The Generator Node 
     The Generator node is an essential component of SoundNet because it is responsible for introducing tokens into the network. Tokens are generated by this node at a rate that is determined by an input Value node. 
     FIG. 15 is a flowchart of the present invention Generator node. The process begins with step  1500  which receives an input clock signal and passes the process on to decision step  1502 . Decision step  1502  passes the process on to step  1506  if the current time is greater then or equal to the next burst time which is the time for the next scheduled token generation. If the current time is not greater then or equal to the next burst time then step  1502  passes the process on to step  1508 . Step  1508  then ends processing for this node. 
     Step  1506  passes a token to each output and then passes the process on to step  1510 . Step  1510  then determines the next burst time by adding the current time and the burst periods. Step  1510  the processing ends. 
     Edges 
     Edges, outputs, connect SoundNet nodes to form a network. An Edge has a single property that is a probability value associated with the edge. The probability value is used by the Probability routing node in distributing a token to one of its outgoing edges. 
     Tokens 
     Tokens are the execution mechanism in SoundNet. Nodes are activated upon the receipt of a token. Tokens have a single property that is their lifetime. A token will propagate through the network until its lifetime has expired. This enables the application to specify a length of time for a behavior to occur. 
     Generating SoundNets 
     SoundNets may be generated manually by programmatically instantiating nodes and connecting them using edges. Interactive editing software can greatly expedite the process by allowing users to interactively create, modify and connect nodes to form a SoundNet while viewing a graphical representation of the network. 
     A natural extension that is possible given this representation of a sonic environment is the automatic generation of SoundNets. One possible technique is to use an existing recording of an environment and extract an equivalent SoundNet representation by performing stream segregation and statistical analysis on the component sounds in the recording. Another possible approach is to use Genetic Algorithms to “grow” SoundNets based on some fitness criteria provided by the user. Both techniques are currently under investigation. 
     As shown by the present invention, sound modifying nodes include but are not limited to play sound, play script, move sound, and modify sound. 
     As shown by the present invention, traversal nodes include but are not limited to counter , delay, probability, signal, broadcast, gate, generator, and network. 
     An intended use of SoundNet is to produce ambient sounds for augmenting architectural spaces. Possible spaces include but are not limited to: museums, public buildings, private offices, resturants, and private residences. 
     Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than specifically described herein.