The following article is about the basic science of the human voice and helpful tips on equalization techniques to enhance voice transmission. Following the article is my experience with the topic. Layne AE1N
Roughly speaking, the speech spectrum may be divided into three main frequency bands corresponding to the speech components known as fundamentals, vowels, and consonants.
Speech fundamentals occur over a fairly limited range between about 125 Hz and 250 Hz. The fundamental region is important in that it allows us to tell who is speaking, and its clear transmission is therefore essential as far as voice quality is concerned.
Vowels essentially contain the maximum energy and power of the voice; occurring over the range of 350Hz to 2000 Hz. Consonants occurring over the range of 1500 Hz to 4000 Hz contain little energy but are essential to intelligibility.
For example, the frequency range from 63 to 500 Hz carries 60% of the power of the voice and yet contributes only 5% to the intelligibility. The 500Hz to 1 kHz region produces 35% of the intelligibility, while the range from 1 to 8 kHz produces just 5% of the power but 60% of the intelligibility.
By rolling off the low frequencies and accentuating the range from 1 to 5 kHz, the intelligibility and clarity can be improved.
Here are some of the effects EQ can have in regards to intelligibility.
- Boosting the low frequencies from 100 to 250 Hz makes a vocal boomy or chesty.
- A cut in the 150 to 500 Hz area will make it boxy, hollow, or tube-like.
- Cuts around 500 to 1 kHz produce hardness, while peaks about 1 and 3 kHz produce a hard metallic nasal quality.
- Cuts around 2 to 5 kHz reduce intelligibility and make vocals woolly and lifeless.
- Peaks in the 4 to 10 kHz produce sibilance and a gritty quality.
Frequency (Hz) Effects
80 – 125 Sense of power in some outstanding bass voices
160 – 250 Voice fundamentals
315 – 500 Important to voice quality
630 – 1000 Important for a natural sound. Too much boost in the 315 to 1K range produces a honky, telephone-like quality.
1250 – 4000 Accentuation of vocals
5000 – 8000 Sibilance (the “S” sound – sizzling bacon sound)
Effects of Equalization on Vocals
Easy-To-Remember 5 Golden Rules Of EQing
- If it sounds muddy, cut some at 250Hz.
- If it sounds honky, cut some at 500Hz.
- Cut if you’re trying to make things sound better.
- Boost if you’re trying to make things sound different.
- You can’t boost something that’s not there in the first place (cut before boosting).
Tricks and Tips (Source: ArtistPro)
- Use a narrow Q (bandwidth) when cutting; use wide Q’s when boosting If you want something to stick out, roll off the bottom; if you want it to blend in, roll off the top.
- For Vocals: Boost a little at 125 Hz to 250 Hz to accentuate the voice fundamental and make it more “chesty”-sounding. The 2 kHz to 4 kHz range accentuates the consonants and makes the vocal seem closer to the listener.
I have a modern transceiver, the Yaesu FT-950. Among it’s features are:
- Three-Band Parametric Microphone Equalizer wherein you can adjust the Center Frequency, Gain, and “Q” (bandwidth).
- Speech Processor which inserts compression to increase average talk power…
- SSB Transmitter bandwidth to adjust the audio spectrum.
Now my personal settings are NOT for everyone but since I am a “casual contester and dx chaser”, after much experimentation, I wound up with the following settings:
- Parametric Amplifier:
Low – Frequency 400 Hz; Level minus 20 dB; Width 10 (widest).
Medium – Frequency 700 Hz; Level minus 20 dB; Width 10.
High – Frequency 2300 Hz; Level plus 10 dB; Width 10.
- Speech Processor. Excessive compression gain will result in degradation of the transmitter signal signal-to-noise ratio, thereby reducing intelligibility. I set mine at “1” (the minimum setting.)
- Transmitting bandwidth: A narrow bandwidth compresses the available transmitter power into less spectrum, resulting in more “talk power” for DX pile-ups. I set mine for 400-2600 Hz (the narrowest).
If you have such features in your rig, you might experiment a bit.Be sure to write down the original settings though so you can go back!
73, Layne AE1N
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