How to distinguish high frequency, intermediate frequency and low frequency in portable bluetooth speakers

This project is very simple to understand, but it is also very simple to cause misunderstandings in textual communication. How to say it? Everyone's convenient speakers will say: the high pitch of this pair of speakers is too strong and the bass is too little. This is the distribution of volume in the high, medium and low frequency bands. The problem is that if the bandwidth from 20Hz to 20KHz is divided into only three segments, it will inevitably produce "not precise enough" confusion. What exactly does your bass mean? How low? In order to make the description more accurate, it is necessary to subdivide the 20Hz-20kHz bandwidth. Portable bluetooth speaker

According to the United States TAS and Stereophile's classification method is very simple, they subdivide each of the high, medium, and low into three sub-segments, that is, into "lower intermediate frequency, intermediate frequency, higher intermediate frequency" division method. This division is like the twelve equal law, quite regular. However, when applied to the Chinese, some small translation problems have arisen, such as "lower mid-frequency" we call "mid-low frequency" or "low mid-frequency"? What about higher low frequency? Is it "high and low frequency"? As far as the Chinese are concerned, this division of foreigners may not work. So long ago I referred to the bandwidth of musical instruments and the name of the sound of the orchestra, and divided the frequency of 20Hz-20KHz into seven segments: extremely low frequency, low frequency, medium low frequency, medium frequency, medium high frequency, high frequency, extremely high frequency, etc. . The nouns in these seven paragraphs are in line with the habitual names of ordinary Chinese people, and they are easy to remember and will not be confused.

Very low frequency

I call this octave from 20Hz-40Hz extremely low frequency. There are very few instruments in this frequency band, probably only instruments such as double bass, bass bassoon, tuba, pipe organ, and piano can reach such a low range. Since this extremely low frequency is not the most beautiful range of an instrument, composers rarely write notes that low. Unless pop music is deliberately arranged with an electronic synthesizer, extremely low frequencies are really of little use to audio fans. Some people misunderstand a job, saying that although the pitch of an instrument is not that low, the overtone can be as low as the pitch. Originally this is not correct, because the fundamental tone of the instrument is the lowest note of that note, and the tone will only climb up by double, triple, quadruple, quintuple, etc., and there will be no downward note. . This is like you tighten a string, the full-length vibration frequency of the string is the fundamental tone, and the vibrations of one-half, one-third, one-quarter, and one-fifth? The string length is the overtone. The addition of the fundamental tone and the overtone is the timbre of the instrument. In other words, even if the fundamental tone (pitch) of the violin and the flute are the same, the timbre will be different.

Low frequency
The frequency from 40Hz-80Hz is called low frequency. What instruments are there in this frequency band? Bass drum, double bass, cello, bass bassoon, bassoon, bass telescope, bass clarinet, touba horn, French horn, etc. This frequency band is a great contributor to the foundation of a solid low frequency. Generally, people will mistake this frequency band for extremely low frequency because it sounds really low now. If the volume of this frequency band is too small, the feeling of abundance and surging will definitely not be there; and it will lead to the prominence of the middle and high frequencies, making the sound out of balance and not durable.

Medium and low frequency
From 80Hz-160Hz, I call it low frequency. This frequency band is the most troublesome section for audio fans in Taiwan, because it is the culprit that caused the ear boom. Why is this frequency band so simple that it has a peak? This is related to the length, width, and height of the small room. In order to remove this annoying peak, most people try their best to absorb this frequency band so that the ears will not crash. Unfortunately, when your ears don't sound like a bang, the lower low frequency and the upper mid frequency may have been sinking with the absorption of the mid and low frequencies, making the sound thinner and lacking a sense of fullness. What's more unfortunate is that most people think this situation is right because the peak disappears. This is one of the reasons why many people's homes are not full of sound. The instruments in this frequency band include the instruments mentioned in the low frequency band just now. By the way, timpani and bass are also added.

IF
The frequency spanning three octaves (320Hz, 640Hz, 1280Hz) from 160Hz-1280Hz is called intermediate frequency. This frequency band almost includes all musical instruments and human voices, so it is the most important frequency band. Readers' biggest misunderstanding of the range of musical instruments also occurs here. For example, most of the violin's range is in this frequency range, but most people mistakenly think it is very high; don't think that the soprano range is very high, generally speaking, her highest range is only at the upper limit of the mid-frequency.

From the above description, you must also understand how important this intermediate frequency is in the sound. As long as this frequency sinks, the sound performance becomes thinner immediately. Sometimes, this thinness is simply interpreted as "false agglutination." I believe that there are a lot of audio fans who are in the mid-frequency depression without realizing it. The importance of this frequency band can also be analyzed from the crossover point of the two-way speaker. Generally, the crossover frequency of a two-tone speaker is mostly around 2500Hz or 3000Hz, that is to say, the tweeter is responsible for above 2500Hz, and the mid-bass monomer is responsible for below 2500Hz. This 2500Hz is about twice that of 1280Hz, that is to say, in order to fear that the bass unit will produce too much crossover point distortion at the mid frequency limit, the designers have all increased the crossover point to twice the mid frequency limit. In this way, the most perfect midrange can be announced by the bass unit. If this statement is correct, what does the tweeter do? If you have ever put your ears close to the tweeter, you will hear a "hissing" sound, which is where most of the overtones are located. If there is no tweeter to announce the hissing sound, just use a mid-bass unit to sing music, it must be gloomy. Of course, if it is a speaker with a three-tone circuit design, most of the mid-range frequency will be contained in the mid-range unit.

Medium and high frequency

From 1280Hz-2560Hz is called medium and high frequency. What kind of instruments are there in this frequency band? The violin has about a quarter of the higher range here, the upper range of the viola, the upper range of the flute, the clarinet, the high range of the oboe, the half of the lower range of the piccolo, cymbals, triangles, etc. Please note that small speakers are not in this frequency range. Originally, the mid-to-high range is very easy to identify, as long as the high range of the string group and the high range of the wood pipe are both mid-to-high range. Many people mistake this frequency band for high frequencies, so please pay special attention.

high frequency
From 2560Hz-5120Hz, I call it high frequency. This section of frequency domain is now rarely involved in musical instrument performance. Except for the upper range of the violin, the high range of the piano, and the piccolo, most other instruments will not appear in this frequency band. From the crossover point of the speaker, we can find that all this frequency domain is presented in the tweeter. As I said before, when you bring your ears close to the tweeter, what you hear is not the sound of the instrument, but a hiss. From the performance of the tweeter, it can be proved once again that the tweeter rarely announces the fundamental tone of an instrument or human voice, it only announces the high overtones of the fundamental tone.

Very high frequency
From 5120Hz-20000Hz such a wide frequency band, I call it extremely high frequency. From the fact that there are very few musical instruments present at high frequencies, you can understand that very high frequencies contain all the overtones of musical instruments and vocals. In general, the overtones of musical instruments tend to have lower energy at higher heights. In other words, the tweeter must be made very sharply and can clearly reproduce very slender sounds. From here, there has been a work that plagues the production of speaker units. That is how to have the best of both worlds? What is "both worlds"? Have you ever thought that if a tweeter wants to regenerate all the delicate overtones, it is desperate The design is designed to be able to drive the diaphragm with a small current, so the high-energy high-frequency and mid-frequency that are also responsible by this tweeter may often be in a state of distortion, because the energy of these two frequency bands is higher than that of extremely high The frequency is too much. This is also one of the reasons why many loudspeakers on the market understand very high frequencies, but are simply piercing.
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