Born in the 30s, the equalizer is the oldest and most commonly used sound processing by sound engineers. Today, the market has a wide variety of instruments for timbre correction – from a simple low-frequency corrector of the 50s to a sophisticated multi-band equalizer with perfect parameters. At its core, the equalizer is a few electronic filters that allow you to change the amplitude-frequency response of a sound device. Over the past half century, the equalizer circuitry has improved tremendously, trying to satisfy the increased demands of the audio industry.
Understanding the essence of timbre correction and its effect on the sound signal
Let us dwell on the explanation of two areas of application of the equalizer, namely the voice and its musical accompaniment. I want to discuss the various spectral components of sound – what they do for the sound itself, and how we perceive it. Why is sound sometimes harsh or dirty? Why sometimes we can’t make out the lyrics? I will try to give answers to these questions and, in general, bring at least a little clarity to the mystical world of equalizers.
Roughly speaking, the spectrum of the voice can be divided into three main bands corresponding to the main speech components – the basis, vowels and consonants.
The area of the voice base is located on a rather limited part of the spectrum – approximately between 125 and 250 hertz. The basis allows us to determine who exactly speaks, and therefore, its correct transmission is an integral part of high-quality sound.
The vowels conducting the greatest vocal energy occupy the band 350 to 2000 hertz. Consonants located on a plot from 1500 to 4000 hertz have little energy, but they are the main component of intelligibility of the voice.
For example, a portion from 63 to 500 hertz accounts for about 60% of all voice energy, but it only affects 5% of intelligibility. The region of 500 – 1000 hertz provides 35% of intelligibility, while the range from 1 to 8 kilohertz accounts for 5% of energy and 60% of intelligibility.
By reducing the level of the components of the low-frequency part of the spectrum and increasing the level in the range from 1 to 5 kilohertz, you can significantly increase the intelligibility and clarity of voice. Here are some of the possible consequences of a rough timbre interference in a sound:
raising the frequency response in the area of 100 – 250 hertz makes the vocals echoing;
cutting out a plot of 150 to 500 hertz gives rise to emptiness, groundlessness;
a decrease in the level from 500 to 1000 hertz entails excessive rigidity;
raising a part of the spectrum of about 3 kilohertz carries a rigid metal nasal;
a decrease in gain in the band from 2 to 5 kilohertz leads to a general decrease in intelligibility, makes the sound lifeless;
raising the area from 4 to 10 kilohertz leads to whistles and the appearance of “sound sand”.
Vocal Correction Consequences
In all cases, it is best to use an equalizer with adjustable parametrics to confidently control the tone.
80 – 125 hertz Giving sensuality to singers singing in a bass register.
160 – 250 hertz Sound base.
315 – 500 hertz Very important for high-quality sound.
630 – 1000 hertz Important for natural sound. Excessive lifting results in a “telephone sound”.
1250 – 4000 hertz Articulation of vocals, manner of performer.
5000 – 8000 hertz Very important for legibility.
1250 – 8000 hertz Give purity and clarity.
5000 – 16000 hertz Excessive amplification results in a loose, whistling sound.
Too strong an increase in the level in the area of 200 – 400 hertz leads to the disguise of consonants, such as “m”, “b”, “c”. Too strong an increase in the level in the range of 1000 – 4000 hertz leads to rapid fatigue of hearing. The vocal can be lightened slightly by raising around 3 kilohertz, while reducing the gain at the same frequency for all accompaniment instruments.
Mixing instruments is a real art, and the sound engineer has to turn to the equalizer more than once before he finds the sound he needs. Many instruments have such a powerful and rich sound that it is almost impossible to transmit a close-set microphone. This is where the equalizer comes to the rescue, the main purpose of which is to convey to us this sound in its most natural form.
The transparency of the sound of many instruments can be significantly increased by emphasizing their harmonics. Our ear hears them even in the lowest sounds with a seemingly narrow spectrum. Drums are one of such instruments, the sound brightness of which can be significantly increased by simply reducing the gain in the lower part of the spectrum, thereby emphasizing the harmonics existing in the sound. Here are a few thoughts about what exactly some of the frequencies do with sound and how our ears feel.