question: How does a single speaker create so many distinct sounds at once?
comment: Your eardrum does the same thing on the receiving side. Sound waves are changes in pressure. They add up . There is only one pressure value at a given point in space and time. The speaker and eardrum only need to move in the same way that pressure changes. Your brain does the magic of separating the single pressure stream into piano and vocals.
passages: "The variety of noises is infinite. If today, when we have perhaps a thousand different machines, we can distinguish a thousand different noises, tomorrow, as new machines multiply, we will be able to distinguish ten, twenty, or thirty thousand different noises, not merely in a simply imitative way, but to combine them according to our imagination." 
  
  Section::::Six Families of Noises for the Futurist Orchestra.
  
  Russolo sees the futurist orchestra drawing its sounds from "six families of noise":
  
  BULLET::::1. Roars, Thunderings, Explosions, Hissing roars, Bangs, Booms
  
  BULLET::::2. Whistling, Hissing, Puffing
  
  BULLET::::3. Whispers, Murmurs, Mumbling, Muttering, Gurgling
   CASA attempts to recreate sound source separation in the same manner as human hearing, but in machines. Using the principles of CASA, Audience’s earSmart processors act like a human cochlea and group different sounds, based on a diverse list of cues such as pitch, onset/offset time, spatial location and harmonicity. These simultaneous sounds are evaluated and grouped by source. In doing this, the microphones of a mobile device, together with Audience's proprietary "Fast Cochlea Transform" technology, can identify and group sounds which are classified as noise, remove or at least reduce them, and leave the remaining clear voice signal intact.
   The human brain must also solve this problem in real time. In human perception this ability is commonly referred to as auditory scene analysis or the cocktail party effect.
  
  Section::::Applications.
  
  Section::::Applications.:Cocktail party problem.
  
  At a cocktail party, there is a group of people talking at the same time. You have multiple microphones picking up mixed signals, but you want to isolate the speech of a single person. BSS can be used to separate the individual sources by using mixed signals. In the presence of noise, dedicated optimization criteria need to be used
  
  Section::::Applications.:Image processing.
   Section::::History.:From duo to trio.
   Section::::History.:Early research.
   Cherry conducted attention experiments in which participants listened to two different messages from a single loudspeaker at the same time and tried to separate them; this was later termed a dichotic listening task. His work reveals that the ability to separate sounds from background noise is affected by many variables, such as the sex of the speaker, the direction from which the sound is coming, the pitch, and the rate of speech.
   All sounds are unique in nature. They occur at one time in one place and can't be replicated. In fact, it is physically impossible for nature to reproduce any phoneme twice in exactly the same manner.
  
  According to Schafer there are three main elements of the soundscape:
  
  BULLET::::- Keynote sounds
  
  BULLET::::- Sound signals
  
  BULLET::::- Soundmark
  
  The elements have been further defined as to essential sources:
  
  Bernie Krause, naturalist and soundscape ecologist, redefined the sources of sound in terms of their three main components: geophony, biophony, and anthropophony.
  
  BULLET::::- Geophony
  
  BULLET::::- Biophony
  
  BULLET::::- Anthropophony
  
  Section::::In health care.
   Full-duplex speakerphones are able to transmit and receive simultaneously and there is no discernible change of transmission direction. These phones are much more complicated and often employ sophisticated digital signal processing algorithms to sort out the incoming sound and the sound in the room for echo cancellation. Their cost is also higher than for a half-duplex speakerphone.
  
  Section::::Speakerphone setup.
   In recent years, there had been research on the topic of construction of digital loudspeaker arrays in Digital Sound Reconstruction system using Microelectromechanical systems (MEMS). MEMS microspeaker arrays can be manufactured onto a chip using a CMOS process. A single chip system will have less variations between each subunit compare to a multi-chip system. CMOS-MEMS process reduce the size of each subunit to a few hundred μm in diameter.
  
  Section::::Speakers marketed as digital.
   In many circumstances the segregated elements can be linked together in time, producing an auditory stream. This ability of auditory streaming can be demonstrated by the so-called cocktail party effect. Up to a point, with a number of voices speaking at the same time or with background sounds, one is able to follow a particular voice even though other voices and background sounds are present. In this example, the ear is segregating this voice from other sounds (which are integrated), and the mind "streams" these segregated sounds into an auditory stream. This is a skill which is highly developed by musicians, notably conductors who are able to listen to one, two, three or more instruments at the same time (segregating them), and following each as an independent line through auditory streaming.
   Although there are many complexities relating to the transmission of sounds, at the point of reception (i.e. the ears), sound is readily dividable into two simple elements: pressure and time. These fundamental elements form the basis of all sound waves. They can be used to describe, in absolute terms, every sound we hear.
  
  In order to understand the sound more fully, a complex wave such as the one shown in a blue background on the right of this text, is usually separated into its component parts, which are a combination of various sound wave frequencies (and noise).
   WFS is based on the Huygens–Fresnel principle, which states that any wavefront can be regarded as a superposition of elementary spherical waves. Therefore, any wavefront can be synthesized from such elementary waves. In practice, a computer controls a large array of individual loudspeakers and actuates each one at exactly the time when the desired virtual wavefront would pass through it.
   Section::::Terminology.
  
  The term "loudspeaker" may refer to individual transducers (also known as "drivers") or to complete speaker systems consisting of an enclosure including one or more drivers.
   With this technology, phrases can be put together whereas the voice owner may never have spoken. For instance, statements can be made with a public figure's voice that and used against them. Imagine the voice of the United States President declaring war on a country without."When a natural source such as a human voice or a musical instrument produces a sound, the resulting acoustic wave is generated by a time-varying excitation pattern of a possibly time-varying channel, and the sound characteristics depend both on the excitation signal and on the production system."
  
  Section::::Technology.
   Section::::Design and application.
  
  Acoustic enhancement systems use microphones, amplifiers, and loudspeakers interconnected with some form of processing. The number, type, and placement of microphones and loudspeakers varies according to both the application, as well as the physics limitations that are imposed by the inherent operating principles associated with each manufacturer's equipment. In most instances, however, these systems employ at least one array of loudspeakers that are distributed throughout the venue.
   Several approaches have been proposed for the solution of this problem but development is currently still very much in progress. Some of the more successful approaches are principal components analysis and independent component analysis, which work well when there are no delays or echoes present; that is, the problem is simplified a great deal. The field of computational auditory scene analysis attempts to achieve auditory source separation using an approach that is based on human hearing.
   Section::::Listening environment.:Placement.
   BEAST can consist of up to over 100 channels of loudspeakers, often arranged largely in pairs or rings, and includes ultra-low frequency loudspeakers ("bins") and custom-built trees of high frequency speakers ("tweeter trees") which can be suspended above an audience.
   The technology can also reproduce a 3D soundtrack into today's conventional formats, like 5.1, 7.1 or any future multi-loudspeaker format. The reverse is also possible: any given loudspeaker layout may also be simulated in the actual physical loudspeaker layout using the concept of "virtual speakers". All proposed and to-be-proposed multi-speaker layouts are part of embraced by this technology, thus rendering future channel based approaches obsolete.
   The analysis of raw fundamental frequency curves for the study of intonation needs to take into account the fact that speakers are simultaneously producing an intonation pattern and a sequence of syllables made up of segmental phones. The actual raw fundamental frequency curves which can be analysed acoustically are the result of an interaction between these two components and this makes it difficult to compare intonation patterns when they are produced with different segmental material. Compare for example the intonation patterns on the utterances "It's for papa" and "It's for mama".
  
  Section::::Algorithm.
   The interaction of a loudspeaker system with its environment is complex and is largely out of the loudspeaker designer's control. Most listening rooms present a more or less reflective environment, depending on size, shape, volume, and furnishings. This means the sound reaching a listener's ears consists not only of sound directly from the speaker system, but also the same sound delayed by traveling to and from (and being modified by) one or more surfaces. These reflected sound waves, when added to the direct sound, cause cancellation and addition at assorted frequencies (e.g., from resonant room modes), thus changing the timbre and character of the sound at the listener's ears. The human brain is very sensitive to small variations, including some of these, and this is part of the reason why a loudspeaker system sounds different at different listening positions or in different rooms.
   BULLET::::1. The Whitacre's virtual choir: A compelling example of the degree of autonomy and self identity members of a spontaneously created network through a VCC is Eric Whitacre's unique musical project that involved a collection of singers performing remotely to create a virtual Choir. The resulting effect of all the voices illustrated a genuine virtual collective empathy merging the artist mind with all the singers through his silent conducting gestures.
  
  BULLET::::2. The Harlem Shake dance:
   A problem of large behavioral importance is the question of how to group auditory stimuli. When a continuous stream of auditory information is received, numerous alternative interpretations are possible, but individuals are only consciously aware of one percept at a time. For this to occur, the auditory system must segregate and group incoming sounds, the goal being to “construct, modify, and maintain dynamic representations of putative objects within its environment”. It has been suggested that this process of binding sound events into groups is driven by different levels of similarities.
   Most speakers command a range of registers, which they use in different situations. The choice of register is affected by the setting and topic of speech, as well as the relationship that exists between the speakers.
  
  The appropriate form of language may also change during the course of a communicative event as the relationship between speakers changes, or different social facts become relevant. Speakers may shift styles, as their perception of an event in progress changes. Consider the following telephone call to the Embassy of Cuba in Washington, DC.
  
  Caller: ¿Es la embajada de Cuba? ("Is this the Cuban embassy?")br
   The minimum set-up that BEAST would ordinarily use for stereo diffusion comprises a set of loudspeakers which Jonty Harrison terms the "Main Eight". These four pairs of loudspeakers, using BEAST nomenclature, are termed "Main", "Wide", "Distant" and "Rear". The "Main" and the "Wide" speakers together form the main, frontal sound image, the "Main" speakers being placed to act somewhat like the loudspeakers in a typical studio, and the "Wide" speakers acting to stretch that sound image out across the audience's sound stage. The "Rear" speakers, which are behind the audience, provide immersion and the possibility of movement around the audience. Finally, the "Distant" speakers, which are positioned to hold their image behind the "Main" speakers, create a sound whose perspective is distant to that of the "Main" pair. Other speakers are added to this "Main Eight" to allow additional possibilities for sound movement and differing sound perspectives. More recent work with BEAST has explored the possibilities offered by 'massively multichannel' approaches to composition, and 'n-channel' work.
  
raw_presuppositions: Speakers create distinct voices alone. 
raw_corrections: It is not only the speakers that make noises sound different, it is also the eardrum that makes changes that effects how humans perceive the sounds altogether. 