Mic Basics: What is Frequency Response?

Davida Rochman | August 10, 2017

A Shure Educational Podcast

Part two of our three-part series on microphone basics. In this episode, Chris Lyons talks about the frequency response of a microphone, both flat and shaped.

Listen to the Podcast (Right click, save as...)

Editor's Note: This post originally was published on March 3, 2009, and updated on August 10, 2017. 

 

Edited Transcript


A microphone only does one thing. It converts sound into an electrical signal that can be amplified, recorded, or transmitted. But, there are a number of different characteristics that make microphones sound different. These characteristics determine a mic's suitability for a particular application.

In this post, we'll talk about frequency response.

 

 

What is frequency response?


Frequency response defines the range of sound that a microphone can reproduce and how its output varies within that range. The frequency response is the most significant factor in determining the sound signature of a microphone. The frequency response of a mic is represented graphically by a response curve. The two most common types are flat response and shaped, or tailored, response.

Below is an example of a frequency response chart. To learn how to interpret the chart, check out our post titled How to Read a Microphone Frequency Response Chart.

Chart of Frequency Response in HertzWhat's the difference between flat and shaped frequency response?

A flat response microphone is equally sensitive to all frequency ranges, so its response curve is in fact nearly a flat line. A flat response microphone reproduces the sound source accurately with little or no variation from the original sound. That's good if you're recording musical instruments or sound effects, but a mic with a flat response usually doesn't sound good on voices.

A shaped response microphone is more sensitive to some frequency ranges than others. Its response curve has peaks and valleys. Many microphones that have a shaped response are less sensitive to low frequencies, which reduces the pickup of both handling noise and the rumble from the stage when the mic is mounted on a stand. A shaped response microphone also typically has a boost in the upper mid-range, usually between 3,000 and 6,000 Hz. This is called a presence rise, and it enhances the clarity, or "punch," of voices and instruments.

Ideally, whether a microphone has a flat or shaped frequency response, a frequency response curve should be a fairly smooth line. If it has a lot of abrupt peaks and valleys, the microphone probably won't sound very natural, and it may have a greater tendency to cause feedback with a PA system.

Some microphones allow their frequency response to be adjusted to suit different applications. The most common adjustments are a low frequency roll-off control to reduce pickup of room rumble and a boost in the upper mid-range to enhance voice intelligibility.

 

 

Compare Flat and Shaped Frequency Response Sound Samples


Shure offers both flat-response and shaped-response microphones. Here are some samples of instruments recorded with both flat-response and shaped-response microphones.

 

 

 


 

 

 

 

 

 

 

 

*Note: The KSM44 used in this sample has been discontinued.

 

Davida Rochman

A Shure associate since 1979, Davida Rochman graduated with a degree in Speech Communications and never imagined that her first post-college job would result in a lifelong career that had her marketing microphones rather than speaking into them. Today, Davida is a Corporate Public Relations Manager, responsible for public relations activities, sponsorships, and donation programs that intersect with Shure at the corporate and industry level.