analog and digital sound.

Analog sound is that which is stored, processed and reproduced thanks to electronic circuits and other analogue devices. For ex. Magnetic tape (cassette or coil) or vinyl record.

The technology applied to analog sound processing works in the following way: the sound wave produces a vibration in the air that is picked up by a microphone. This converts the vibration into an electrical signal that travels through a cable to the recording device. The recording is produced magnetically (in cassette tape or coil), through sound recording / reproducing heads that make physical contact with the surface of the tape. This leads to wear of the material with use.

The duplication of sound in analog format (copying from one medium to another) always entails a loss of quality. When successive copies are made, increasing quality losses occur.

The Digital Sound, on the other hand, is the one that is stored, processed and reproduced on digital media, in the form of numerical data. There are several digital sound storage devices: minidisc, DAT, CD-Audio, CD-Rom, DVD, DCC, hard disks, floppy disks, zip and jazz, (including the video tape, since the audio track that incorporates it is digital).

The capture of sound by the microphone is the same as in the analog case. But the electrical signal it generates is converted into numerical data by an analog / digital converter (sampler) that interposes between the micro and the recording device.

This process of converting the signal into numerical data is done several times per second and is called Digital Sound Sampling (sampling). The sampling frequency is measured in Khz. In CD-Audio this frequency is 44.1 Khz. (professional quality). On the computer and on CD-Rom, the necessary sampling frequency is lower: 22 Khz is enough for music and 11 Khz for speech.
It is preferable to work with the highest sampling frequency allowed by the equipment and reduce it at the end, doing a downsampling.

The resolution of the digital sound can be 8, 16, 24 or 32 bits. The higher the resolution, the more space the file occupies. Computers usually work at 8 or 16 bits of resolution.

Digital sound can also be generated on the computer itself. There is a standard called MIDI (Musical Instrument Digital Interface) that allows you to save the "instructions" of playing musical sounds (only instruments, but not voices), so that any computer with the appropriate software can play on your card. sound those "instructions" thus executing the melody composed in MIDI. The great advantage of this standard is the small size of its files, which allows its use on the Net.

Digital sound also has two fundamental advantages over analog sound. First, digital audio editing does not have to be linear and, therefore, is considered "non-destructive" (any step of editing can be modified without altering the rest of the recording). Second, the successive copies do not lose quality.


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