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DIGITAL AUDIO

SOUND SYNTHESIS

In electronic music the sound produced by the speaker that moves due to a voltage variable. This fluctuation does not necessarily come from the recording process of an actual sound, but can be performed directly by electronic means. There are many methods to produce a synthesis of sound, some of which will in general: Method repeat fixed wavelength, subtractive synthesis, additive synthesis, nonlinear synthesis, as proposed by NÚÑEZ, Adolfo (1993), in the 2nd edition of his book "Computer and electronic music."

a-Method REPETICIÓN WAVE FIXEDEL OSCILADOR

The basic oscillator is the device most important for the synthesis. Its effect is to cyclically repeat a particular waveform, thus producing a periodic oscillation.

 
ENCLOSURES
A jacket is a temporary curve that shows the evolution of a parameter. In the case of the oscillator can be used to surround the scope, frequency and timbre.

 
MODULATION OF LOW FREQUENCY

Modulation is the alteration of a parameter of an oscillator signal by another, if this signal is periodic is called velocity modulation. The modulation of low frequency vibrato is similar to that performed by singers and string instruments and wind for more expressiveness. Its name refers to the speed of modulation, which is lower than about 20Hz. In fact among the instruments is between 4 and 8 Hz and above 20 Hz originate phenomena timbre.

b-subtractive SYNTHESIS METHOD

This method is part of a signal is passed through a filter that modifies the spectrum, some partial mitigating and reinforcing others. In principle can be applied to any type of signal, but that is interested in the richest possible partial, as with the waveforms periodic pulse rate and noise. Containing pulses with high energy and harmonics are obtained by a suitable oscillator. Noise generators exist for both analog and digital.

TYPES OF FILTERS

Any device which alters the spectrum of a signal is a filter. For example, if you talk through a tube, it acts as such, and that changes the timbre of our voice, to lessen or strengthen some harmonics that match the resonance frequencies of the object.

MODIFICATION OF DEVELOPMENTS timbre

Applying a filter whose characteristics vary over time, to an oscillator waveform sets, one can get their spectrum varies dynamically. For example, if decreasing the cutoff frequency of a low-pass filter the spectrum changes from bright to off.

c-method ADDITIVE SYNTHESIS

This method creates a sound mix of money or through others. The additive synthesis is to add more general sinusoidal oscillators, each representing a part with amplitude and frequency spectrum needed to be built; here is the great advantage of this method because the synthesis parameters match the spectrum. These parameters can be empirically established to achieve the desired sound or obtained by analyzing a certain signal.

ADDITIVE SYNTHESIS EMPIRICAL

Is to specify directly the envelopes of amplitude and frequency of all partial and necessary to vary these parameters by trial and error until you get the ringer searched. This method is very difficult and slow, because for a moderately complex sound is normal to use more than 15 parts.

ADDITIVE SYNTHESIS BASED ON THE ANALYSIS

Any method of synthesis can be based on an analysis. The procedure to follow is to analyze the sound and extract the parameters used in the re-synthesis of the same sound. If the sound synthetic and real is identical, the model works, otherwise it would have to rethink the analysis.

ADDITIVE SYNTHESIS WAVES WITH COMPLEX

For additive synthesis can be complex waves such as square or triangular, this will get very rich spectra with few oscillators, but has the difficulty that can not be controlled directly as spectra, as it did when working with sine waves.

d-Method of NONLINEAR SUMMARY

The additive synthesis is linear, since the operations involved in this process are the sum or multiplication by constants. The synthesis method described in this paragraph is based on Nonlinear operations with variables, such as multiplication, exponentiation, etc. It is above all to achieve a complexity of sound by using a few oscillators, which means equipment more or less simple computer calculations, as well as control the timbre manipulation by a few parameters.

This technique is also called "distortion", as it is a distorted wave in order to get more complex.

Synthesis by frequency modulation (FM)

The configuration of simple FM synthesis is not different in any way with the vibrato of height mentioned in paragraph a. Frequency sine wave called a carrier wave varies according to other known modulating frequency fm.

Amplitude modulation (AM)

The amplitude modulation at low frequency results in a tremolo, but from higher frequencies between 10 and 20 Hz, is beginning to perceive a timbre that can be used for synthesis.