There are plenty of ways to describe the sound of a microphone. Presence is one of these factors and is an especially common metric in vocal microphones.
What Does “Presence” Mean In Terms Of Microphones? The term “presence” refers mostly to the “presence band” of audible frequencies (described loosely as 3 kHz – 6 kHz). In microphones, presence refers to the mic’s response/sensitivity to this band. Mics with “good presence” boost this range appropriately and allow vocals to cut through denser mixes.
In this article, we’ll discuss the presence band of frequencies and why it’s an important range for us as humans and for our microphones.
What Is The “Presence” Frequency Band?
The presence range in audible frequencies is most often described as 4 kHz to 6 kHz. Note that human hearing is typically described as being between 20 Hz – 20 kHz.
There aren’t many instruments that have fundamental frequencies in this range (the highest notes of pianos, organs, and some violins get up there). Rather, the presence range is home to many important harmonics in mid-range instruments and higher harmonics in bass instruments.
The presence range is responsible for clarity and definition in most sound sources.
This is not because instruments generally play notation in this range (they rarely do). Rather it’s because human hearing is particularly sensitive to this range.
Cutting frequencies in the presence range will reduce the amount of clarity in an audio signal and cause it to sound distant. However, boosting this range too much will result in an overly harsh and irritating sound.
Human Hearing In The Presence Frequency Band
As mentioned above, the reason why the presence range of 4 kHz to 6 kHz is so important is that our ears are naturally sensitive to this band of frequencies.
Like microphone frequency response (which we’ll get to later in this article), our hearing has its own response to audible frequencies. That is to say that we do not naturally hear all frequencies the same.
In general, our hearing response can be summed up with the Fletcher-Munson curves:
Let’s describe what we see in this curve:
- Sound pressure level: this is the measure of the localized pressure deviation from ambient pressure that is caused by a sound wave. Decibels sound pressure level (dB SPL) is a way of measuring sound pressure logarithmically relative to the threshold of human hearing (0 dB SPL).
- Frequency: audible sound waves have a frequency range of 20 Hz – 20,000 Hz (Hertz = cycles per second). In general, sounds are made of many frequencies, often with a fundamental (note) and harmonics (integer multiples of the fundamental). Humans generally hear higher frequencies as having higher pitch. This is particularly true of fundamentals.
- Phon: this is a unit of loudness for a pure tone (a single frequency). Phons represent our psychoacoustic sensitivity/response to sound pressure at specific frequencies. The phon is psychophysically matched to a reference frequency of 1 kHz, meaning that X phon at Y db SPL is X phon at 1 kHz, though it will likely not be at another frequency.
So the X-axis of the Fletcher-Munson curves graphs represents the audible frequencies (20 Hz – 20,000 Hz) while the Y-axis represents the sound pressure level (dB SPL). The curves represent the phons and relate perceived loudness (hearing sensitivity) at different frequencies and sound pressure levels.
Let’s look at the 0 phon line, which represents the threshold of human hearing. We see that it take a whole lot more sound pressure at the lower limits of human hearing (20 Hz) than in the presence range (4-6 kHz) to have the same perceived loudness.
Humans have developed sensitivity in this range over our evolution as a species. The presence range is home to speech intelligibility, which is of critical importance for us as social animals.
So we are naturally more sensitive to sounds in (and close to) the presence range. Therefore, an increase in “presence” of an instrument, microphone, or mix will literally sound more present to us.
A strong presence in vocal microphones and mixes is imperative to hearing clear intelligible vocals, especially in a dense audio mix!
Microphone Frequency Response
As we’ve touched on above, microphones can have strong or weak presence. They can also have neutral presence (which is typical of uncoloured mics, which we’ll get to shortly).
Microphone presence has to do with microphone frequency responses. Like our ears, which are more sensitive to some frequencies than others, each microphone has its own frequency response.
Microphones that exhibit a presence boost in their frequency responses help vocals (and other instruments) to cut through noisy environments and dense audio mixes. They do so, of course, with the risk of sounding overly harsh and coloured.
Not every instrument should have its presence range accentuated and, similarly, not every microphone should have a presence boost in a balanced mix. Presence should be looked at as a way of bringing certain sound sources to the front of the mix.
A great example of a microphone that exhibits a presence boost is the legendary Shure SM58.
Let’s look at its frequency response graph here:
As we see above, the SM58 has a 5 dB boost in the presence range (and beyond). This is a big part of the mic’s charm and why it excels as a live vocal microphone.
The roll-off in the low-end reduces the amount of mechanical noise the 58 picks up. The high-end roll-off helps to reduce cymbal wash and other high-end sounds. Together, these help to improve gain-before-feedback in live situations.
But most importantly (to this article, at least) is the natural sensitivity of the SM58 in the presence range. This presence boost along with the high gain-before-feedback of the 58 allows it to excel on vocals. Vocal performances cut through the audio mix with great clarity due to the presence boost.
Of course, the Shure SM58 is far from sounding “natural.” Its coloured frequency response does help tremendously with vocals and it’s an excellent live microphone. However, the roll-offs and the boost in the presence range heavily colours the sound waves the mic picks up.
A much more natural sounding (uncoloured) mic example is the AKG C414.
Let’s take a look at the frequency response of the AKG C414 XLII in cardioid mode:
As we see above, the frequency response graph is pretty well flat across the audible frequency spectrum (unless a highpass filter is engaged). This means the C414 will capture sound very naturally but will lack a strong presence.
As an aside, you can learn more about high-pass filters by reading my article What Is A Microphone High-Pass Filter And Why Use One?
So choosing a microphone with a slight frequency response boost in the presence range will help to accentuate instruments and vocals. As discussed, this is because our ears are naturally sensitive to the presence band (4 kHz – 6 kHz).
For a detailed article on microphone frequency response, please check out the My New Microphone post Complete Guide To Microphone Frequency Response (With Mic Examples).
What does a microphone measure? A microphone essentially measures the sound pressure variations at its diaphragm within a range of audible frequencies. As the sound waves cause varying pressures around the mic diaphragm, the mic produces a coinciding electrical audio signal.
For more information on microphones, sound, and audio, check out my article What Do Microphones Measure And How Do They Measure?
What is a microphone capsule? The mic capsule is the part responsible for the conversion of sound waves into mic signals. Capsules always feature diaphragm(s) and the housing for those diaphragms. The capsule, in its entirety, acts as the transducer of the microphone, turning sound into audio.
For further reading on microphone capsules, check out my articleWhat Is A Microphone Capsule? (Plus Top 3 Most Popular Capsules).