I recently did an overview on the best vocal mics for every budget, and in comparing different microphones I often cited their frequency responses. Let’s identify what is a microphone’s frequency response, what it means, and why it matters.
What is a Microphone’s Frequency Response
A microphone’s frequency response is the frequency range that microphone is capable of recording and thus capturing in an audio track.
Generally speaking, the human ear is able to perceive everything between 20Hz and 20,000Hz, also known as 20khz or 20k for short, although this will certainly vary from person to person.
Some people have difficulty hearing frequencies on the lower end of that spectrum, and others have difficulty hearing frequencies on the higher end. Others still might have some “blind” spots if you will where they have difficulty hearing particular frequencies in between the extremes, especially in the high mid to high range, but I digress.
The main thing is you obviously want a microphone which is capable of capturing as much of that range as possible.
But also similar to people, most microphones have particular frequency “pockets” they’re better or worse equipped at perceiving and, in the microphone’s case, thus capturing on a recording, even if they’re capable of capturing the majority of the 20Hz-20kHz range.
Unsurprisingly, you’ll find that cheaper microphones have a weaker frequency response on the low end in particular.
The AT2020 is a very affordably priced microphone from Audio-Technica at just $99, but you can see its frequency response seriously drops off on the low end beginning around 200Hz:
This can be a liability if you’re looking for a microphone for recording a speaking voice when low end body is important. While you can somewhat address this via EQ for voice over, you’re better off spending a couple or few hundred more dollars to get a microphone which doesn’t have the limitations on the low end which will have your recordings lacking power, body, and warmth.
The Shure SM7B has a more solid and consistent presence across the mids, low-mids, and low frequencies:
While it has some liabilities in the presence oriented frequencies above 7k which might not make for an ideal vocal mic, its treatment of the lows and mids make it the go-to microphone for podcasters and radio personalities:
It’s very likely that if you’ve ever watched a live recording of a radio or podcast style show, you’ve seen that microphone as it’s seemingly the de facto relatively affordably priced microphone for people who talk for a living.
As I covered in the aforementioned guide and overview on the best vocal mic, you need to get into that $500 and up range to begin finding microphones with the most balanced and faithful frequency responses.
Take the Audio-Technica AT4050; an excellent balanced microphone for a relatively reasonable price (which also boasts additional polar patterns) based on the microphone’s frequency response:
You can see there’s zero dropoff below 100Hz (the dotted line refers to the optional high pass filter switch). There’s a small spike around 5k and a larger one at 10k for a small boost in presence, but otherwise this is arguably the most well rounded microphone from a frequency response perspective for the money.
Something else to keep in mind, obvious though that it is, is that you can always cut an abundance some microphones have at a certain frequency due to their greater sensitivity.
While you can boost a weaker response range on a microphone or supplement it via saturation, it’s not as easy or effective as simply using a microphone capable of capturing the full frequency response.
