Audio Masking Effect – Part 5
Auralization
The established task of reconstructing the signal in its original form is quite complicated and includes many aspects that must be considered. In this case, you fit a definition that describes modern trends and tries to form a high-precision sound field. Auralization (named by analogy with the definition of “visualization”) will help achieve similar results. Auralization is a way of recreating a 3-D sound field, trying to influence the final signal in a certain way to recreate a feeling of spaciousness and modulate a binaural auditory sensation at a given position in space. The human auditory system is influenced by only two main parameters: 1) the energy intensity or pressure of the sound wave; 2) the time of formation and decay of the signal, the change of periodicity and frequency in time. Other aspects of perception are the result of signal processing by the hearing aid and the brain. These are parameters such as: timbre of the sound, volume, height, width and depth of the scene, etc.
If you imagine the ideal situation for a certain audio signal recorded in a damped chamber or in a professional recording studio, then it is not difficult to trace what factors ultimately affect the final signal under real conditions. The main obstacle to recreating a high fidelity sound image is listening volume. When listening to such a signal in an ordinary room / hall, it turns out that the room acts as a linear filter due to the appearance of reflected waves, as well as attenuation, diffraction and other processes. In addition, the head and ears of each individual listener perform their own processing of the already “filtered” signal. If we somehow take into account all the previous transformations of the audio signal and carry out the appropriate filtering (for example, using an equalizer), it is quite possible to restore the very feeling of a three-dimensional sound field, which was established at the time. sound recording. In the primitive case, this function can be handled by a conventional equalizer, both a band pass (if configured correctly), and an equalizer with “presets” to filter a specific room (cathedral, concert hall, opera hall, amphitheater). However, the task is much more complicated than it seems at first glance, and to this day its final solution has not been found.
It should also be noted that the process of “correcting” the original signal with an equalizer is extremely undesirable and has a strong negative effect on the quality of the signal, introducing a large amount of distortion into the original path. If we draw a brief intermediate conclusion at this stage, then we can safely say that, as an alternative to using the equalizer, it is much more correct and priority to fine-tune the sound by changing the room / volume parameters for listening, achieving the desired effect of depth. and amplitude of the soundstage. The reverberation process, which is the process of attenuation of sound waves as a result of multiple reflections, has the greatest impact on the sound in a room. That is, the reverberation time is important or the decay time of the signal by an amount of 60 dB. The structure of early reflections, the nature of late stage attenuation, and a host of other characteristics also play an equally important role in the subjective sense of spatiality and fullness of the sound. It is thanks to this that a person can distinguish a good room (hall) from a bad one in acoustics.
