Many people have used voice recorders. Do you know the principle of voice recorders?
In 1898, the Danish scientist Poulsen stretched a steel wire used as a magnetic carrier when conducting a recording and playback experiment in 1898, and then suspended an electromagnet equipped with a pulley on the steel wire as a recording and playback head, which was used as the transmitter of the telephone. Connect to the coil of the magnetic head. When a person speaks loudly into the microphone, the head will slide along the wire to record. A similar method is used when playing the sound. The electromagnet is used as the playing head and the receiver is used as the earphone. When the head is sliding, people can listen to the previous recording. Simply put, it uses electromagnetic induction to record sound signals on a magnetic carrier.
Traditional recorders use this method in the recording and playback experiment. The surface of the recording tape is coated with magnetic powder. When the magnetic head in the tape recorder is recording, the coil in the magnetic head generates a magnetic field due to the recording current passing through, magnetizing the tape in transmission, leaving a magnetic recording signal in the tape. During playback, the magnetic recording signal in the tape is converted into a current signal on the coil of the playback head to drive the horn behind to sound.
With the development of recording technology, traditional voice recorders have been replaced by digital voice recorders. After sampling and encoding the analog signal, the digital voice recorder converts the analog signal into a digital signal through a digital-to-analog converter, and then performs a certain compression for storage. Because there is no need to use a magnetic carrier to record sound, the digital signal is copied many times, and the sound information will not be lost.
Compared with traditional voice recorders, digital voice recorders are composed of memory, flash memory and integrated circuits, and have the advantages of small size and light weight. At the same time, the continuous recording time of the digital voice recorder is long, usually 5 to 8 hours, and some can even reach dozens of hours. In addition, traditional tape recorders have a limited lifespan, and their internal mechanical structure will wear out during use. An ordinary tape will basically be scrapped if it is repeatedly recorded and erased dozens of times. The digital voice recorder uses an electronic structure, which can be wear-free and has a relatively long service life.
Over the years, the functions of the voice recorder have been constantly updated. Some voice recorders can also transcribe recordings into text, which can be divided into two methods: real-time transcription and first recording and then transcribing. With the continuous development of technology, recording technology will continue to be updated.
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