The Technical Microphone Specifications Explained

We explain the many technical microphone specifications for better understanding

What are the different microphone specifications? Which mic technical terms should I be aware of? Have you ever tried to shop for a new microphone and found yourself confused by the specifications, abbreviations, and technical terms listed on the side of the box? Microphone’s have several different types and each type has its own purpose and best applications. Furthermore, each brand or model of microphone might have subtle differences in their specifications. This guide should help to define some of these terms and inform you on how to make a smart decision when purchasing your next microphone.

Microphone specifications contents

The basics of sound

The first thing we have to understand is what a microphone does. A microphone converts sound into an energy signal that can be either amplified or digitized depending on your application. Sound exists in rapid changes in air pressure commonly referred to as “sound waves.”

We explain microphone specifications, in particular sound wavesThe figure here does a good job of illustrating the different aspects of sound waves. Each hill and valley is called a compression and a rarefaction respectively. The vertical size of the compression and rarefaction will determine the volume of the sound, the frequency of each cycle will determine the pitch. As such, the pitch an instrument produces is also referred to as a frequency.

Each microphone has its own unique range of frequencies it can capture as well as a sensitivity measurement which tells you the range in volume that will be picked up by the microphone.

Some microphones specialize in picking up very loud sounds clearly without “fuzz” or “static” coming through. Some microphones specialize in picking up sounds at very high frequencies, while other microphones specialize in picking up very low frequency sounds. The microphone market is also flooded with microphones that can pick up everything, highs and lows as well as louds and softs, decently but not as well in any specific range as a specialized microphone.

The basics of the microphone

A microphone is basically a mechanical recreation of our human ears. Sound travels into our ears and against our ear drums, a membrane that captures the vibration, and our brain interprets those vibrations into what we perceive as sound. The “ear drum” of the microphone is the transducer. Depending on the type of microphone you are using, the technology for the transducer can vary. Types of transducers include condenser, dynamic, ribbon, carbon, fiber optic and laser. For more on this check out our microphone types guide.

Regardless of the type of transducer used in a microphone, the same principle applies: a microphone’s transducer picks up sound waves and interprets them to an electric signal. The transducer is always just beneath the grille of the microphone (this is the part you speak into). Usually there is some type of foam pop filter just underneath the grille. This foam does its best to capture sudden bursts of air created by hard consonant sounds like “P’s” and “B’s”. It also blocks some wind noise. The pop filters that are built into the microphone are usually insufficient. Additional pop filters can be purchased later and attached on top of the microphone’s grille.

Microphone polar patterns

The construction of the microphone, the alignment of the transducer, and the type of transducer all play into a microphone’s “Polar Pattern.” Essentially, a polar pattern is simply a diagram of how efficiently a microphone will pick up sound coming from different angles. A microphone’s polar pattern will be shown on the box using one of the following symbols (these are the most common):

Omnidirectional

The omnidirectional polar pattern in microphones

Omnidirectional microphones have equal sensitivity at all angles. An omnidirectional mic could be placed in the middle of a room faced in any direction and would be able to pick up sound coming from anywhere in that room.

Bidirectional or Figure Eight

The bidrectional polar pattern in microphones

Bidirectional, or more commonly referred to as “figure eight” polar patterns pick up sound from the front and rear of a microphone at equal levels, but do not pick up sound from the sides.

Cardioid

The cardiod polar pattern in microphones

Cardioid microphones have the most sensitivity at the front and that sensitivity tapers off around the sides reaching a null point with no sensitivity in the rear. These microphones are ideal when monitor speakers are being used to reduce the risk of feedback.

Supercardioid

The supercardioid polar pattern in microphones

Similar to cardioid microphones, this polar pattern offers good sensitivity in the front with a slightly more focused pattern making the microphone more directional and less likely to pick up ambient sounds in loud environments. This polar pattern does however have some sensitivity in the rear.

Microphone technical specifications explained

With a general understanding of sound and how microphones work, we can now go down the list of common specifications found on a product description for a microphone and explain each one.

Decibel (dB) scale & frequency response

The decibel scale gives a number to the volume of sound based on a reference point of 0 dB. The decibel scale used for measuring frequency response on a microphone is not the same as a decibel scale used for measuring volume. There is a decibel formula that explains this conversion but it is very confusing, I don’t even understand it. Take for example this frequency response chart for a famous Shure SM57 cardioid dynamic microphone:

The microphone technical term frequency response chart visualized

As you can see, most of the frequency response for this microphone falls plainly on that 0 dB line. For the purposes of buying a microphone, anything that falls on that 0 dB line is a frequency that the microphone picks up very well, anything below the line it picks up but not as well, and anything above the line it might be overly sensitive to.

Frequency response refers to the microphone’s ability to detect high and low sounds. The human ear can on average detect sounds from 20 Hz to 20,000 Hz. Going back to our discussion of sound waves, a Hz (Hertz) is one cycle of compression and rarefaction in a sound wave. The number refers to how many times that cycle occurs in one second. Here are some reference points for typical instruments and their frequencies:

  • 15 Hz – The lower end of the range sound a kick drum makes
  • 41 Hz – The low open E string on a Bass guitar
  • 440 Hz – The open A string on a guitar
  • 4,000 Hz – About the middle of the range of sound a Hi-Hat makes

Multiple frequency response curves

On higher end equipment, manufacturers will include frequency response curves for sounds coming at various angles towards the microphone. This is helpful for studio recording situations.

Sensitivity

A microphone’s sensitivity refers to how much sound or signal a microphone can handle before it will start to distort the sound. This is measured using another complicated formula however the important thing to understand is that a microphone with a high level of sensitivity will send more signal and therefore will not require as much gain on your mixer, while a low sensitivity microphone will send less signal and will require more gain on the mixer.

Conclusion

These measurements are not the only specifications you’ll find on a microphone’s product description however I feel they are the ones that most microphone users will be able to wrap their heads around. Also, know that these measurements do not paint a complete picture of the quality of the microphone that you are researching. There is no substitute for trying out the microphone yourself and measuring with your ears that microphone’s ability to recreate sound. In your research, you’ll find microphones with very similar specifications and very different prices.

I have always found that it’s almost always worth it to spend a little more on audio equipment. The quality of construction, durability, and quality of parts do not show up on the specifications of a microphone. There is also a reason that you see the same two or three brand names on microphones at studios all over the world. Feel free to read through microphone guides if you’re looking for more advice on buying.