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.
Editor’s Note: This post originally was published on March 3, 2009, and updated on August 10, 2017.
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.
What’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.
Visit the Mic Listening Lab to compare the sound of many more Shure microphones on vocals and instruments. Note the frequency response description and specs in each mic you compare. Keep in mind that the Lab uses “tailored” rather than “shaped,” but as noted above, they mean the same thing.