What are the high frequency and low frequency in listening test?

High frequency generally refers to the sound above 2000HZ, which is usually manifested as a sharp sound in life.

Low frequency generally refers to the sound below 500HZ, which is usually characterized by low and rough voice in life.

High-frequency sound refers to high-frequency sound, also known as "mosquito sound", "silent ringtone" and "ringtone that adults can't hear" The sound that the human ear can distinguish is in the range of 20 Hz to 20000Hz. Generally speaking, all kinds of sounds used by human beings for communication are in the range of 200 Hz to 2000 Hz. However, scientific research shows that with the increase of age, people's hearing will gradually decline.

Therefore, young people may be very sensitive to the high-frequency sound of 17000 Hz, but when they reach a certain age, they become deaf. But this kind of sound will damage the ears, and in severe cases, deafness will occur. This kind of clock first appeared in 2005 and was made by a security company in Wales. Its original intention is to help shopkeepers disperse young people gathered at the door without disturbing adults.

3. "Voice of Teenagers"

The so-called "silent bell" is actually a sound with a frequency of about 17000 Hz. Using it as a ringtone, the teacher is basically unconscious, although the short messages in the students' ears are one after another. Therefore, students affectionately call it "the voice of teenagers".

4. "Silent ringtone" uses the most basic acoustic principle. The frequency of sound that the human ear can hear is between 20 and 20,000 Hz. With the increase of age, people's hearing will decline, first of all, the sensitivity to high-frequency sounds will decline. Research shows that most people basically lose their ability to recognize sounds above 17000 Hz after 35 years old.

5. Frequency refers to reading hertz in hertz, and low-frequency noise refers to the sound with a frequency below 200 hertz (octave). In China, the sound frequency range of low-frequency noise is 20~200Hz, and the frequency that has obvious influence on human body is mainly in the frequency range of 3-50Hz.

6. It is a low frequency in the range of 20 Hz-200 Hz, that is, the irregular sound generated by vibration for 20 to 200 times in one second is called low frequency noise. The frequency is 500Hz~2kHz, and the high frequency is 2kHz~ 16kHz.

7. The so-called low-frequency noise refers to the sound with a frequency below 200 Hz (octave). There are five main types of low-frequency noise sources in residential quarters: elevators, transformers, water pumps in high-rise buildings, central air conditioning (including cooling towers) and traffic noise. The sound that ordinary people can hear is between 20Hz and 20000Hz, below 20 Hz is infrasound, and above 20000 Hz is ultrasonic.