As electronic devices built with vacuum tubes, used microphonics, a very serious problem had to be design. The contaminated items in the vacuum tubes would vibrate and produce the movement, the spacing to change and would charge flows in and out of the hose, which is identical to a condenser microphone is in a sense. A system that is sensitive to microphonics is enough to know feedback.
With the arrival of solid state electronics (transistors)
The sound of the guitar amplifier to the electronic chassis in the same cabinet and speaker, you are susceptible to microphonics. Although the distortion of a guitar amplifier microphonics as part of some "special tone" is estimated at a guitar amplifier, a faulty vacuum tube or other part can get out of hand feedback. Redundant microphonics associated audible deformation can often be reduced by using commercially available vacuum tube dampers.
The term sound can be defined from two different perspectives. Physiologists define the sound in terms of auditory sensations produced by longitudinal disturbances in the air. For them, the sound does not exist in a distant planet. In the same line of thought, philosophy posed that question that says: if a tree falls in a forest and no one listens, his downfall was "sound? All of this is true if we consider the framework. We do not focus on the physical definition of sound, which refers to shocks by themselves and not to the sensations they produce.
For there to be sound, there must be a body to vibrate. Consider a guitar string. When
press the string, it vibrates, "going and coming" with respect to its rest position, until the shaking stops.
This movement is translated into the air particles, which will be "bumping" each other.
The vibration propagates (travels) through an elastic medium. This elastic medium can be air, water or any solid. The sound wave is propagated by vibration of molecules, transferring energy to each other generating pressure variations that reach our ears as sound waves. That is, the spread occurs because the air molecules will "collide" with each other, as would happen if we have a row of balls pool and hit the line at one end. The last ball will move but the row will remain in place. Also exemplifies the familiar motif consisting of steel balls suspended in line, where the first and last made a pendulum motion, without moving the spheres of the environment. Without elastic medium that propagates the vibration of the source, no sound. The sound does not propagate in vacuum.
The perceived loudness, or property that causes it to capture as strong or weak, is related to the intensity of the sound wave concerned, which in turn depends on the magnitude of vibration. Returning to example of the guitar, the harder we press the rope, the greater the movement, the greater the number of displaced particles, and thus higher
INTENSITY will sound (more volume).
Some acoustic phenomena
Reflection, diffraction and absorption
As with light, sound waves are reflected when they hit a surface. The wave reflected at an angle equal to the incident angle. The best known phenomenon caused by the reflection is the echo.
Not all surfaces reflect sound the same. Part of the wave impacts the surface absorbed, and the different frequencies are absorbed in different proportions. How much energy is absorbed and to frequencies, depends on a property of materials known as "absorption factor." Generally speaking, the hard surfaces such as smooth walls, glass, ceramics, reflecting almost the entire incident sound. The soft surfaces absorb much of the wave, especially at high frequency. Diffraction occurs because the waves are capable of piercing holes and obstacles put in skirting his way. When a wave reaches a plate with a central hole or crack, the hole behaves in focus wavelets issuing all of the same frequency. Secondary foci that correspond to the ends of the opening generated waves are responsible for the beam after the slit open and go around corners.
The audio signal
Call signal to the electrical current that represents the sound within electronic equipment. The sound wave is converted into electrical signal through a transducer. A transducer is a device that 'translates' values a certain physical magnitude to values of another physical quantity, with which there is a definite mathematical relationship.
The human voice is produced in the larynx, with the bulk, the glottis, is the true organ of phonation human. The air from the lungs during exhalation is forced through the glottis, shaking The two pairs of vocal cords, which resemble two double tabs. So-called "strings" vocal, in fact of truth are not strings are membranes. The cavities of the head, related to the respiratory system Nasopharyngeal act as resonators, printing the characteristic timbre of each person.
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