The Knowledge of Audio Properties

- Oct 18, 2018-

Digital audio is a way for us to save sound signals and transmit sound signals. It is characterized by the fact that signals are not easily lost. The analog signal is what we can finally hear.

The most critical step in digital recording is to convert analog signals into digital signals. As far as the computer is concerned, the analog sound signal is recorded as a Wave file. This is also possible with the tape recorder that comes with Windows. However, its function is very limited and cannot meet our needs, so we replace it with other professional audio software, such as SoundForge. Wait. The recorded file is a Wave file. The description of the Wave file mainly has two indicators, one is the sampling precision and the other is the bit rate. This is two very important concepts in digital audio production. Let's take a look at it.

What is the sampling accuracy? Because Wave is a digital signal, it uses a bunch of numbers to describe the original analog signal, so it needs to analyze the original analog signal. We know that all sounds have their waveforms, and the digital signals are in the original. The analog signal waveform is “taken” every once in a while, giving each point a value. This is “sampling”, and then all the “points” are connected to describe the analog signal. Obviously, the more points you take in a certain period of time, the more accurate the waveform is described. This scale is called “sampling accuracy”. Our most common sampling accuracy is 44.1kHz/s. It means that 44,100 samples are taken every second. The reason why this value is used is because after repeated experiments, people find that this sampling accuracy is the most appropriate. Below this value, there will be a more obvious loss, and the ear is higher than this value. It has been difficult to distinguish and has increased the space occupied by digital audio.

Generally, in order to achieve "very accurate", we will also use the sampling accuracy of 48k or even 96k. In fact, the difference between 96k sampling accuracy and 44.1k sampling accuracy is definitely not so different as 44.1k and 22k. We use the sampling standard for CD is 44.1k. Currently, 44.1k is still the most popular standard. Some people think that 96k will be the trend of the recording industry in the future.

Bit rate is a term that everyone often hears. Digital recording generally uses 16 bits, 20 bits, and 24 bits to make music. What is “bit”? We know that the sound is light and loud, and the physical element that affects the light is the amplitude. As a digital recording, it must also accurately represent the soft sound of the music, so we must have an accurate description of the amplitude of the waveform. "Bit" is such a unit. 16 bits means that the amplitude of the waveform is divided into 216 or 65,536 levels. According to the light response of the analog signal, it can be represented by a number. As with the sampling accuracy, the higher the bit rate, the more detailed the light response of the music can be reflected.



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