AUDIO PROCESSING DEVICES.
There is a strong belief among common people that sound processing devices can improve the quality of a professional sound reproduction system. This is true … However, this thesis should not be extrapolated to the quality of the sound that this system reproduces.
When using any sound processing device, its quality, in principle, can only deteriorate. The fact is that they do not solve the problem of the sound itself at all, but allow sound engineers and sound engineers to level the harshness of the performance of vocalists and musicians, eliminate inaccuracies in the sound of musical instruments, compensate defects caused by the wrong choice of equipment and its location, and also reduce the impact on reproduction. the acoustic properties of the premises. But if, for example, a vocalist has a good command of his voice and knows how to use a microphone, then he does not need a compressor.
Initially, the processes associated with the special distortion of the reproduced signal were used only in commercial sound systems, such as telephones, radio or public address systems. They have now found wide application in music and are used to make an instrument or voice unusual or unnatural. This is done primarily to surprise the audience and increase the impact of listening to the piece.
From a scientific point of view, any audio device (a microphone, a power amplifier, or a speaker system) is also a sound processing device. Firstly, they are not ideal and change the amplitude and phase of the signals, secondly, these changes occur in different ways at different frequencies, and thirdly, non-linear distortions in them lead to the appearance of new components spectral in them. By the way, the first sound processing device was the Leslie loudspeaker, which was used in conjunction with the Hammond electric organ in the 1930s and 1940s and gave it a “growl” sound.
Parameters and classification of audio processing devices.
Sound work can be done in both digital and analog formats, or even without electroacoustic conversion. In this sense, it is necessary to decide: what is meant by sound processing device?
Therefore, we will consider software and hardware that works with audio frequency electrical signals (both in analog and digital form) in real time. Before qualitatively evaluating each of the methods of working with them, it is necessary to understand how and for what purpose the processing of audio signals is carried out.
All audio processing devices can be quite conditionally divided into 3 groups:
1.-devices that do not add additional components to the signal (audio processing units);
2.-devices that add additional components to the signal (sound effects);
3.-devices that synthesize new signals based on the characteristics of the original signal (vocoders).
AUDIO PROCESSING UNITS
These include delay blocks, equalizers, crossovers, and compressors.
The need for delay units appeared in the 40s of the 20th century, when stereo sound began to be used in the cinema. As you know, a person perceives sound as a set of signals that reach each of the ears. By analyzing the delay of the sound wave reaching each ear, our brain can easily determine the location of the sound source.
Using a delay unit, used, for example, on one of the channels, it is possible to simulate a change in the position of the sound source relative to the listener. Of course, in the formation of spatial effects, the listener voluntarily participates in the sound image. In general, sound delay is a natural phenomenon associated with the fact that the speed of propagation of a sound wave is relatively low. Surely everyone is familiar with the echo effect that occurs when a wave reflects off an obstacle and passes its return path. The difference between the effect made with the help of the delay unit is that the “reflected” signal is no different from the original. Under real conditions, the spectrum of the signal during reflection changes significantly, since its various components are reflected differently from obstacles.
An example of sound propagation in a room
Currently, delay units are widely used in audio processors. They are used to equalize the sound field in large and complex rooms, in conference rooms, as well as to create sound effects such as echo, delay, reverb, etc.
