Classifying the Audio Spectrum Frequencies

The terms that we use today for the classification of the spectrum of audible frequency has originated from the music industry, but a part of those also come from scientific worlds, and almost everyone is familiar with these.

Dividing the audible range into the main three groups. Generally speaking, the most understandable and simple grouping of the sound frequency range is as follow:


  • Low frequencies.
  • Mid frequencies.
  • High frequencies.

1. The Three Main Audio Spectrum Ranges

The low-frequency range lies between the limits of 10 Hz – 200 Hz,which are the lower limit and upper limit, respectively. Precisely from where the lower limit starts is 10 Hz, but in actual, a person can hear sounds from 20 Hz. Every sound that’s below 20 Hz lies in the infrasound region. However, the 10 Hz below the 20 Hz can be heard partially. It can be tactilely felt if you are listening to deep low bass and also has the tendency to alter the psychological moods of humans. The low-frequency range sounds are carriers of the enrichment function, saturation of emotions, and final response.

A considerably large number of musical instruments can reproduce low-frequency range sounds. The male vocals also have this capability and can fall in the region of up to 100 Hz

The midrange boundaries start from 200 Hz (lower limit) and go up to 2400 Hz (upper limit).

The middle range is quite important and will always be a basic and defining basis of sounds of any composition. Hence, its significance can not be overestimated. There are different ways of explaining it, but mainly evolution is the cause of this feature of the perception of the human auditory system. During the stages of evolution of humans, our auditory systems started capturing the mid-frequency sound range because of the fact that it also falls within the range in which humans speak. It is also the primary tool for not only effective communication but to also ensure the survival of humans.

The wide variety of sounds, vocals, and musical instruments fall in the middle range. Vocals of both males and females and nearly all the famous instruments, including guitar, piano, keyboard, and wind instruments, fall in this frequency range.

The range of high-frequency sounds has limits that lie between 2400 Hz at the lower limit and 3000 HZ at the upper limit. In the case of the lower range frequencies, the upper limit is somewhat arbitrary and can vary with an individual. For example, a normal human cannot hear any sound above 20 kHz, but there are sensitive people who can hear up to 30 kHz.

Theoretically mentioning, numerous musical overtones can lie in the region, having sounds above 20 kHz. As you might already be aware that the overtones are responsible for the sound color and the final timbre perception of the holistic picture of the sound. Apparently, the ultrasonic frequencies that are “inaudible” can not be listened to in a usual way but can influence a person’s psychological state. On the other hand, by analogy to the sounds with flow frequency, the high-frequency sounds have a role that is quite enriching and complementary.

The high frequencies are responsible for providing the music track with clarity, “airiness”, purity and transparency. Numerous musical instruments are also designed to play in high-frequency rage, including vocals that also have the potential to go into the region of above 7000 Hz with the aid of harmonics and overtones. The most noticeable musical instruments in the high-frequency domain are the strings and winds, and violins and cymbals can reach the audible range’s upper limit (20 more comprehensively.

No matter what the case, the role of almost all high frequencies that are audible to humans is quite remarkable. The high-fidelity (hi-fi) class of sounds or higher is reproduced to ensure the most reliable and the best linear sound of the respective frequencies with each other since it took place at the time of phonogram recording in the studio. The prevalence of strong peaks and dips in the speaker system’s frequency response shows that it cannot play music, which the author or sound engineer initially conceived at the stage of recording due to its design features.

When listening to music, a person is able to hear all voices and instruments collectively, and each of these sounds falls within a certain frequency range. The frequency range of some instruments may be very narrow or limited, while others, on the contrary, may extend laterally the lower and upper audible limits.

In addition to that, various frequencies of sound which populate the audible frequency range has an associated unique threshold pain sensitivity!

For example, the average frequency of 2000 Hz has a pain threshold of 112 dB, on the hand, the pain threshold of a 30 Hz sound is 135 dB. At lower frequencies, the pain threshold is higher in comparison to the medium and high frequency.


2. The Audio Spectrum split into small subsets

Apart from the three general groups of the audible range, which are well-known and widely accepted, sometimes the narrow parts need to be expanded and examined in more detail. Therefore, the sound frequency range can be further split into smaller “fragments.”

Lower bass (10 Hz to 80 Hz) represents the least audible sounds and has the longest wavelength. These sounds usually have sufficient intensity and can be felt tactile. The phrase which describes this effect accurately is “you feel the sound with your whole body.”


Upper basses (from 80 Hz to 200 Hz) can be experienced through classical bass instruments’ upper notes and the lowest audible frequencies of string instruments, including guitar. The upper bass range has the purpose of sensing the power associated with a sound along with the transmission of the energy potential.

The lower middle (from 200 Hz to 500 Hz) represents the area of the sound frequency range in which almost all instruments and vocals (including both male and female) lie. The overtones and lower harmonics fill the vocals in this region. It is also of extreme significance to transmit the vocals and saturation correctly.


The middle (from 500 Hz to 1200 Hz), which can also be referred to as pure middle, is the portion of the frequency range where the main notes, as well as harmonics of a lot of instruments, are present. Brightness, intelligibility, clarity, and penetration of sound are dependent on the amount of saturation of the middle.


The upper-middle (from 1200 Hz to 2400 Hz) is a quite slim and demanding segment of the frequency range. Here, not many basic notes exist, which make up the base of the sound of any voice or instrument. But a majority of overtones and harmonics instills the audio with sharpness and character.



The lower high ones (from 2400 Hz to 4800 Hz) is the region where the distortion is significantly increased. This portion carries the majority of the load associated with the high-frequency range. As far as the sound is concerned, their manifestation happens mainly with residual and well-heard harmonics of mainly female vocals as well as several instruments.


Medium-high (from 4800 Hz to 9600 Hz) is generally considered the perception limit and depends on the individual’s characteristics, including age. In music, the frequencies impart feelings of transparency, purity, “airiness” and definite subjective completeness.


Upper highs (from 9600 Hz to 30000 Hz) are quite complex and incomprehensible and mostly provide support for some vocals and instruments. The upper high range primarily gives the qualities of airiness, crystallinity, transparency, coloring, and some elusive additions, which might be insignificant or inaudible for many. To build a high-end sound usually called “hi-fi” or “high-end,” close attention is paid to the highest treble range as it is believed rightly that even the least details in the sound can be preserved.

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