Sound capacity of a computer or device?
Recently, the capabilities of multimedia equipment have grown significantly, but for some reason this area has not received enough attention. The average user suffers from a lack of information and is forced to learn only from his own experience and mistakes. With this article we will try to eliminate this annoying misunderstanding. This article is aimed at a common user and aims to help you understand the theoretical and practical foundations of digital sound, to identify the basic possibilities and techniques of its use.
What exactly do we know about the sound capabilities of a computer, except that our home computer has a sound card and two speakers? Unfortunately, probably due to insufficient literature or for some other reason, but the user, in most cases, is unfamiliar with anything other than the built-in Windows audio input / output mixer and recorder. The only use of a sound card that a common user finds is to play sound in games and listen to a collection of audio. And after all, even the simplest sound card installed in almost every computer can do much more: it opens up wide opportunities for everyone who loves and is interested in music and sound, and for those who want to create your own music, a sound card. it can become an omnipotent tool. To find out what the computer can do in the field of sound, you just need to take an interest, and you will be presented with opportunities that, perhaps, you did not even know about. And all this is not as difficult as it might seem at first glance.
Some facts and concepts that are difficult to do without:
According to the theory of the Fourier mathematician, a sound wave can be represented as a spectrum of frequencies included in it.
The frequency components of the spectrum are sinusoidal oscillations (so-called pure tones), each of which has its own amplitude and frequency. Therefore, any vibration, even the most complex shape (for example, a human voice), can be represented as the sum of the simplest sinusoidal vibrations of certain frequencies and amplitudes. On the contrary, by generating different vibrations and superimposing them on each other (mixing, mixing), you can get different sounds.
Reference: The hearing aid / human brain is capable of distinguishing between 20 Hz and ~ 20 kHz sound frequency components (upper limit may vary based on age and other factors). Also, the lower limit fluctuates a lot depending on the intensity of the sound.
Digitize sound and store it on digital media
“Normal” analog sound is represented on analog equipment as a continuous electrical signal. The computer operates with data in digital form. This means that the sound on the computer is also represented in digital form. How does the analog to digital conversion work?
Digital sound is a way of representing an electrical signal using discrete numerical values of its amplitude. Let’s say we have a good quality analog audio track (by saying “good quality” we will assume a silent recording that contains spectral components from the entire audible frequency range, roughly 20 Hz to 20 KHz) and we want to “feed” it into a computer. (that is, digitize) without loss of quality. How to achieve it and how does digitization occur? A sound wave is a kind of complex function, the dependence of the amplitude of a sound wave on time. It would seem that since it is a function, you can write it to a computer “as is,” that is, describe the mathematical form of the function and store it in the computer’s memory. However, this is practically impossible, since sound vibrations cannot be represented by an analytical formula (like y = x2, for example). There is only one way left: to describe the function by storing its discrete values at certain points. In other words, at each moment you can measure the value of the amplitude of the signal and write it down as numbers. However, this method also has its drawbacks, as we cannot record the amplitude values of the signal with infinite precision and we are forced to round them. In other words, we will approximate this function along two coordinate axes: amplitude and time (approximate in points means, in simple terms, taking the values of the function in points and writing them with finite precision). Therefore, the digitization of a signal involves two processes: a sampling process (sampling) and a quantization process. Sampling process is the process of obtaining the values of the converted signal at certain intervals.
