Understanding Microphone Frequency Response – Basics Guide

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If you were to buy a microphone now, there will a lot of factors you would be noting to get the right sounding microphone. This characteristic property called ‘microphone frequency response’ helps us technically understand how a microphone is going to sound like.

There are a lot of different types of microphones, mainly condenser and dynamic microphones. All these microphones are basically transducers – which convert sound waves to electrical signals.

What is Microphone Frequency Response?

When the input sound to a microphone reaches the inside parts, it does some sound processing and delivers an output sound which includes our vocal details and the signature of microphone processing.

This output is graphically represented across frequencies, called the microphone frequency response.

It will look very similar to the below graph. The X-axis represents frequencies (Hz) and Y-axis represents relative sensitivity (in dB).

Normally a frequency response chart will have only a single line.

This however is from a blue yeti microphone, and its capability of supporting multiple recording patterns (like stereo, omnidirectional, cardioid & bi-directional) for different purposes outputs respective frequency plots.

Even though this chart looks confusing to a buyer at first look, it’s relatively easy to understand.

The only pre-requirement is the general knowledge of sounds, and their classification with respect to frequencies – low, mids, upper mids, highs, and so on.

Understanding Sound Frequencies EQ

Sound EQ (also referred to as “Equalizer” or “Equalization”) is the changes that are made to the frequency response of a sound application device, as part of the better sound adjustment.

If you keep quiet in your room or any place where you want to record sounds, definitely there would be unwanted sound disturbances. Sounds from a particular source you want to capture will always be in some fixed frequency range.

Hence, the manufacturers design each microphone perfectly to work in each scenario, be it for podcasting, voice narrating, gaming, or any other purposes.

A cleaner audible sound is all we users want, and if we choose the microphone for our use-case, most part of our post-processing work is already done.

[su_note note_color=”#ffd266″]Sound EQ can be implemented directly into the sound hardware or be done in post-processing using computer software like FXSound, Adobe Audition.[/su_note]

As you know, the frequency of a microphone is the number of times the sound wave repeats itself per second. It is measured in Hertz (Hz).

The general human hearing range is from 20 Hz – 20,000 Hz. Thus, all the sounds and music you hear through the studio speakers would always be in this range.

We can classify the sounds with respect to frequencies as follows:

1. Sub-Bass (20 Hz – 70 Hz)
2. Bass (70 Hz – 250 Hz)
3. Low Mids (250 Hz – 600 Hz)
4. Mids (600 Hz – 2 kHz)
5. High Mids (2 kHz – 8 kHz)
6. Highs (8 kHz – 20 kHz)

[su_highlight]Do keep in mind these are rough boundary ranges. There is no official range as such, only an approximate concept.[/su_highlight][su_spacer]

Also, these are the generic audio terms you would head audiophiles talking of when they describe their experience on using any sound equipment device.

Comparing Frequency Response with Sound Chart

The frequency response pattern here showed is for omnidirectional mode. It picks up sound equally from all around the mic.

It’s best used in situations when you want to capture the ambiance of “being there”—like recording a band’s live performance, a multi-person podcast, or a conference call.

A human’s voice spans across frequencies of 125Hz to 8kHz. This commonly adopted equalization to all sound recording devices, and filters out very low-frequency sounds, to extensively prevent intake of buzzing sounds.

This is very important if the microphone is sensitive in all directions (also referred to as “omnidirectional”).

Further, as you can see the response is a small bump towards the lower mids (~650Hz) and a high bump at high mids (2kHz – 8kHz).

This summarises that the microphone is more sensitive to higher pitch sounds and less sensitive compared to closer-human vocals, as they occur in the mids. Thus, a wider range of sensitivity.

Consider the below frequency chart for a cardioid pattern microphone,

It has a flat response in bass and lower mids range. That’s neither bass-heavy nor thin sound. The 2-3 dB bump in sensitivity between 6 kHz – 8 kHz frequency adds a bit of magical quality to vocals.

Normally cardioid microphone frequency response is flat from 70Hz to around 5kHz, but again, it’s all the signature sound added by the microphone manufacturer.

[su_note note_color=”#ffffff”]One cool fact about sounds is that our human ear is most sensitive to the 2kHz to 4kHz region. This is the most important region for any sounding device.[/su_note]

So here you can expect this microphone to be great for voice-overs, instrument recording, and podcasts. Cardioid mode records sound sources that are directly in front of the microphone, delivering rich, full-bodied sound.

Conclusion

If you are picking a professional studio microphone, The frequency response of the microphone is an important specification that needs to be checked.

If you know how your voice sounds like – whether it’s base heavy or normally pitched, you can pick your required microphone with those specifications in mind.

Make the right choice!