Voice is our means of communication. Voices inform us about what it happens in the flat next to ours, in the streets or in the car. A weeping baby explains a need, the low pitch of a conference invites to listen carefully, the cries of Diamanda Galas take convey us all the pain she want to express. Different worlds of expression sharing the same common idea: they are expression of the voice.
Not any voice, but a voice that is born to be unique, for unique is also the human being who emits it. Voice is the expression of all that is true and hidden inside the human being, it reveals his humanity and singularity. It is the expression of a resonating body, of a vibrating sound cavity which through such vibration shows itself and its very existence.
To wonder about voice means to open new paths to explain this phenomenon, from its perception to its emission, from its artistic implications to its experimentations, with the intention to give rise to some questions and put them in relation with each other. The links between sound and voice, the difficulties in recognizing a sound and the reflection of sound in its producer are only some of the problems we will focus on
There was no longer the faintest sign of vitality in M. Valdemar; and concluding him to be dead, we were consigning him to the charge of the nurses, when a strong vibratory motion was observable in the tongue. This continued for perhaps a minute. At the expiration of this period, there issued from the distended and motionless jaws a voice—such as it would be madness in me to attempt describing. There are, indeed, two or three epithets which might be considered as applicable to it in part; I might say, for example, that the sound was harsh, and broken and hollow; but the hideous whole is indescribable, for the simple reason that no similar sounds have ever jarred upon the ear of humanity. There were two particulars, nevertheless, which I thought then, and still think, might fairly be stated as characteristic of the intonation—as well adapted to convey some idea of its unearthly peculiarity. In the first place, the voice seemed to reach our ears—at least mine—from a vast distance, or from some deep cavern within the earth. In the second place, it impressed me (I fear, indeed, that it will be impossible to make myself comprehended) as gelatinous or glutinous matters impress the sense of touch. I have spoken both of “sound” and of “voice.” I mean to say that the sound was one of distinct—of even wonderfully, thrillingly distinct, syllabification. M. Valdemar spoke—obviously in reply to the question I had propounded to him a few minutes before. I had asked him, it will be remembered, if he still slept. Now he said: “Yes;—no;—I have been sleeping—and now—now—I am dead.” 
The extract makes for very few ways to fantasize about its author: the precision in describing each gruesome detail of an anomalous death leads straight to E. A. Poe. It does not mean this writer particularly influence all the questions around the “voice” topic, but such extract contains an attention towards vocal sounds and their listening which cannot be ignored. The attention used by Poe in the description of an imperceptible sound that comes from the ill’s bloated tongue and is resonated within the mouth’s cavity, reflected by the teeth, makes its own way out and vibrates like that search for sound and voice, seen as expression of a living body. Many artists open to experimentation have always been stimulated by it.
It is not that important the Anglo-American writer meant to illustrate the surprising power of mesmerism. His words leave the door open for many questions linked to the sound-voice relation: its propagation through an indoor space, its chance of being explained with features taken from other senses, and its characteristics which derives from the resonating cavity.
In order to talk about voice it is necessary that we first discuss about a fundamental relation: the link that is born on an acoustic and perceptive level (even more than subjective and emotional) among sound and space. An indissoluble connection, an unmistakable sign of vitality, the mark of a subject that express its being through the power of making his body resonate
To talk about voice it is therefore important to maintain a certain continuity with sound itself. Among the elements of perceptive continuity, maybe the first lies in the voice, seen as its own characteristic of being a sound. All of this implies its chance to become objective, to stabilize its permanence by making it immutable. in other words, philosophically speaking, there is an ontological problem at the origin, concerning the chance to perceive a sound objectively. The essence of sound itself makes it uneasy to perceive; when perceiving a sound, the subject never faces that very sound determined in its presence.
In his essay Music body expression, Carlo Serra clearly suggests us another stimulus to restart from: the experience of sound is not as immediate as all that concerns vision. The aspect of evidence, just lightly touched, is not sufficient anymore, for a web of logical structures rises all around noise, making immediate reference to a fundamental set of notions, a flowering of possible senses: by overcoming the informative level, the listening of sound started a dramatization of space which led to the imaginative valorisation of an environment. 
The step is obvious: unlike sight, that receives steady images in their forms, what hear receipts is evanescent, fleeting and softened, just like it is filtered. Sound in fact, Serra goes on, needs an immediate intervention by logical structures capable of making it understandable. He gives importance to everybody’s imaginative background. The fugacity of sound and its characteristics of stealing all the room during its emission, material component of the room included, is the first aspect shared by voice. Voice in fact implies the presence of a body, or a sounding board that makes that breath objective, just like any sound needs a resonator to gain more tone and force.
Let’s concentrate our attention on tone then. A widely accepted definition of tone is that the particular quality of the sound we perceive, or what allows the distinction of two sounds with the same height and intensity, makes us distinguish two music instruments playing the same note. The same thing concerns a place that receives sounds and makes them resonate , as well as a body or any cavity allowing air molecules to vibrate at the same frequency of the used matter (string, skin or reed). Their resonance within a cavity or a vacuum is what allows sound to be this way, or “to exist in the absence of other things”, or even to be perceived through other things.
This feature is perhaps the most important aspect and permits us to describe sound through space parameters, like a vocal sound getting through a body. An isomorphic relation among the object and its sound exists, which consent to individuate origin, provenience and localization of that sound without any further doubts for it takes the same material and spatial features of the body which transmitted it. 
Sound gets possession of the space surrounding it, just like voice does with the flesh and the cavity of the body emitting it. To this purpose Husserl, explaining the modern parallelism among optics and acoustics, tries to find a bridge between sound and heat, pointing out how the irradiating force of sound takes touches the material features, thus characterizing itself.
Hot and cold, as qualities equally dividing bodies; irradiating qualities, distant but non-visual qualities, the resonating, the heat irradiating, that come out from the body and propagate in the empty space with different forces. The sound the way it lies on the body, coming out from it or a part of that; the ear explores space and catches the sounds present in that place and so catches sound as it is. In case of totally resonating bodies, they do that in every part of them, and from every part of them a sound beam comes out. I bring my hand near a body and it produces heat; I bring my ear near the same body (or I bring all of myself near that body) and it produces sound…a noise. That is what comes out from it. 
The sound source irradiates, spreading its own noise into space and leaving traces of its passage as just like a red-hot iron. Sound spatiality and isomorphism among voice and body make questions rise if we compare them to contemporary experimentations about sound and voice. In the first instance there is the possibility to intervene by microphoning voice, in the second there is the chance to localize, assembly and change the vocal message till its origin source is no more recognizable.
An example of sound retrieving and the relation about the parallelism between the sound datum of voice and the sound itself, and can be found in the development of assembling and use of electronics. The improvement in the utilization of electronics in music, even in its raw form, quickly implies the sound of voice to be fundamental. The reasons for this are different and lie in voice’s simplicity and linearity, in the fact that body is an odd instrument with a will of its own, yet in a different way compared to sounds’ in general, just like the newly born electronics
The similarity with sound is not sufficient to explain voice though. There is a further perceptive problem of voice that must be brought to light about the way we hear our voice itself. Voice is neither objectivable nor disconnectable from its own producer, and a distance that separates voice from its origin place does not exist. The necessary amount of time to completely reveal it as a received sound-objected is always missing. Since the time of its emission, voice remain a closed flow inside the cavity where it is produced. The need to find a space in which voice could become objective led to various experiences, such as echo voice and self-listening: echo removes from voice the subject emitting it and makes voice a sound, a sound object to be heard.
Anyway, despite all of this experiences, in the sound of voice lies an immediate subjectivity: any vocal expression, be it linguistically pronounced or not, implies a subject with specific bodily, expressive and affective characteristics. Every time a sound is born, it has expressive characteristics that generate an union between information and expression.
By discussing a little bit about it, or by taking the starting point from XX century artistic experimentation, it is very interesting to see the use Laurie Anderson made of voice. The American artist is not considered a vocal experimenter, even if she succeeded in utilizing technology better than others did, by illustrating the separation of voice from body. In her famous first album, Big Science, she used two simple devices, the Vocoder and the Harmonizer. The first is a vocal filter, and the latter a frequency transpositor. They both allowed her to make a global work on voice’s language and tone which makes the album seem like a wide set of different subjects: women, men, children and robots.
One of the most important problems strictly linked to the idea of voice and its being in a so intimate relation with the subject is the chance of separating and listening to one’s own voice. In fact the necessary distance for a listening relation never creates. When I listen to a sound, as much as fleeting or uneasy to hear it may be, it keeps a distance from me that makes it an object of my perception, and at the same time it confers an objective stability allowing more subjects to hear it the same way I do. So we all will agree on the fact the tone of a low-pitched sound is grave or every sound created by tubas are thick and so on. In other words, our agreement would be based on that sound perception parameters which make reference to the form it takes in the tone
Nevertheless, for what it concerns the voice it is not really like that: voice begins inside the mouth. It comes from an empty object, not by a filled one. In a cavern, the sound resonates from the cavern itself, and so does the voice, whose origin comes from the breath passing through a vacuity. 
As Piana affirms, the case of human voice is not similar to a vibrating solid body’s: the mouth where sound creates is a vacuum. A vacuum different from music instruments’, because unlike them it only needs breath and not some mechanical actions. The distinction is then made clear: the difference between instrumental and vocal sound lies in the living body involved. A body capable of breathing, providing its cavity, vacuums, like the case described by Poe, and makes them work as if they were resonance devices.
Just like sound objects, body becomes a sounding board with a tone of its own, given by the shapes of its container that allows the sound to propagate, thus turning the tide: voice is the most important sound of body’s matter. Body’s cavity is the horizon where the sound-voice relation takes place, although differently from any other sound cavity. Voice represents above all a will of testifying an existence, of revealing and explaining itself by communicating with other people. Voice focuses the attention on the speaker, explains its affectivity and expressivity, tells us something about his intentions and mostly about his body matter allowing vibration to turn into communication.
 – Poe, “La verità sul caso di Mister Valdemar”, in id., Racconti del terrore, Arnoldo Mondadori, Milano 1985, pp. 295-306.
 – Serra, Musica corpo espressione, Quodlibet, Macerata 2008, p. 18.
 – Cfr. Piana, Barlumi di filosofia della musica, http://www.filosofia.unimi.it/piana/barlumi/barlumi_idx.htm
 – Casati, “Considerazioni critiche sulla filosofia del suono di Husserl”, http://users.unimi.it/~gpiana/dm3/dm3suorc.htm, p. 4.
 – Piana, Filosofia della musica, Guerini e Associati, Milano 1996, p. 82.