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While selecting a microphone for personal or professional usage, you might have encountered various technical terms used in multiple places on the internet. This article will try to encapsulate all those technical wordings and provide you with a simple explanation.
I am pretty confident that these technicalities will enable you to understand more about microphones and will separate you from the general crowd regarding the knowledge about specific technicalities and functionalities of microphones.
What Are Microphones?
Microphones convert sound waves in the air into electrical energy and send them to an audio source or a loudspeaker, where they can be recorded, amplified, or transmitted. You can also categorize it as a transducer that converts acoustic energy into electric energy. They are used for audio recording, recording vocals, and recording instruments.
Microphones are concerned with electrical energy in the form of audio signals or AC electrical signals with a frequency range of 20 Hz–20,000 Hz. In some cases, the lower frequencies are made weaker, so the microphone cannot record or catch the mumbling part of the sound input.
Specifications That Define A Microphone
Microphone sensitivity is the digital or analog output ratio with the amount of input sound pressure applied to it. It is expressed in mV,dBV per 1 Pascal, or 94 dB Sound Pressure Level(SPL). For example, a condenser or an active ribbon microphone can have a sensitivity rating between 8 and 32 mV/Pa, that is, -42 to -30 dBV/Pa.
The sensitivity of a microphone determines its output signal level at any given audio output. It shows how well the mic acts as a transducer and converts acoustic energy into electrical energy. If you are measuring the sensitivity of any speaker, then for best readings, you should keep the speaker at a 1-meter distance and apply 1-watt power from the amplifier.
This microphone specification defines how well microphones respond to sound from various directions. Knowing which kind of polar pattern is required is essential before purchasing any specific microphone type. It is known by reading the polar pattern graph that shows the sensitivity of your mic while you move 360 degrees around it.
Thus, it determines a microphone’s inherent directional sensitivity. It captures sound in a 3-dimensional way in a spherical form that specifies the accurate direction and sensitivity of the mic towards audio directions. The polar response can be omnidirectional, cardioid, or bidirectional, which I have explained later in this article.
It is defined as the range of sounds reproduced by a microphone and how the audio output varies within a given frequency range. It clearly shows the lowest and highest frequencies a microphone can reproduce at any given point. When selecting a microphone for yourself, it should be one of deciding factors. This is because frequency response also gives out the specific sound signature of the microphone.
The commonly expressed frequency response range for microphones to respond to sound is 20 Hz–20,000 Hz. This response determines the frequency-specific sensitivity to sound frequencies.
The maximum sound pressure level, or max SPL, is the maximum sound pressure measured at the microphone’s capsule that a microphone tolerates before the audio signal encounters distortion.
It is the point where sound distortion becomes audible and significant enough to be noticed while capturing audio. The lowest sound pressure level, 0 dB, is the hearing threshold, while the highest sound pressure level is the pain threshold level, 120 dB and above. You can find a maximum sound pressure level specification in condenser microphones and dynamic mics.
If you are a nerd, you might want to know that it is calculated by projecting a 1 kHz audio tone from any audio device directly into the mic’s capsule. This audio tone level is gradually increased to a point where the mic starts to show signs of distortion, i.e., 0.5% of total harmonic distortion, or THD, and the DB SPL is measured, representing the maximum SPL rating.
The microphone’s self-noise is the sound produced by the microphone itself without any disturbance from any external sound. It specifies the clarity of the audio signal, keeping in mind the noise generated by the mic itself.
Self-noise is caused by current running in the circulatory system of the microphone and can be found in active ribbon microphones and condenser microphones. It is produced when no other sound is present in the surrounding area. The air present around the microphone could also cause self-noise in a microphone.
If you want to reduce the self-noise, then you can use a simple pop filter, and you could also use a shock mount as well. Last but not least, you should never bundle the microphone and electric cable together when in function.
What Is A Microphone Transducer
If I talk about a transducer, you can say that it converts one form of energy or a signal into another form of energy or a signal. In the context of a microphone, a microphone transducer works on the same principle, as there is a conversion of energy from acoustic to electrical energy.
Depending on how they work, microphone transducers are categorized into various categories. Don’t be startled by these variations; I’ve already covered a variety of transducers in detail that you should be familiar with if you want to quench your hunger for knowledge about microphones.
These microphones are those range of microphones that convert sound waves into electrical signals through an electromagnetism medium. They have permanent magnets that move using electromagnetic induction. Dynamic mic’s main functionality lies in the diaphragm’s movement with only a magnetic field’s help.
Within the category of dynamic microphones, you might want to note that they constitute moving coil dynamic microphones and ribbon microphones. Clueless about how they work? Let me break down their working mechanism for you.
- Moving coil dynamic microphones: These microphones include a voice coil made of metal, a magnet, and a thin diaphragm setup inside the microphone’s magnetic field, seeming like a sound-driven electrical generator. The voice coil moves when the sound waves hit the diaphragm within the magnetic field. This metal coil induces an electric signal following the phenomenon of electromagnetism, which is relative to the actual sound wave that first hits the diaphragm. As a result, these microphones can easily handle high-pressure sound levels without changing audio quality or distortion.
- Ribbon dynamic microphones: They consist of a ribbon transducer made of thin metal like corrugated aluminum instead of a coil. The ribbon element is balanced between two magnetic poles and moves when a sound wave hits it and turns the sound into electrical voltage. There are several benefits of using a ribbon dynamic microphone. They have a wider frequency response and record warmer tones effortlessly. Not to miss, the ribbon also adds a decent ambiance to the sound. If you are thinking of using a ribbon dynamic mic for studio recordings where more warmth in audio quality is desired, then let me tell you that you have made the right choice in choosing the mic category.
These types of transducer microphones use a capacitor to generate an audio signal. They have a lightweight, conductive vibrating diaphragm that makes these mics highly sensitive to higher frequencies.
They use an electrically charged backplate and a diaphragm to create an audio signal. The diaphragm vibrates in response to the sound waves with the fixed distance between the plate and the diaphragm itself. In most cases, Condenser microphones are active types and require external power from an audio interface or AA batteries.
Features Of Microphones
The polar pattern in microphones is the area or direction from where the audio signal is picked up. It refers to the directional orientation of any microphone. There are different types of polar patterns and you need to know about them as they could enhance or spoil your audio recording experience.
It is a unidirectional polar pattern that captures the sound coming from a particular front direction while rejecting the sound originating from the back and sides of a mic. It resembles the shape of a heart, hence the name “cardioid.”
This polar pattern has the maximum sensitivity at the front of the mic’s capsule at 0° while being the least sensitive to audio coming from behind at 180°. This polar pattern is somewhat sensitive to noise coming from the sides (90° and 270°), making it an ideal pattern for recording vocals.
You can use a cardioid polar pattern mic at live performances that can give you crisp audio quality by capturing dry signals and eliminating background noises. Now you know what type of polar pattern microphone your favorite artist uses at his music tours and live events.
A figure-8 polar pattern in a microphone design, specifies recording sound coming from the front as well as from the rear while rejecting the sound coming in from the sides. It offers equal sensitivity levels at 0° and 180° angles. It is a bi-directional polar pattern that displays extreme rejection of sound coming from the sides.
This polar pattern can enable one to record two voices, like for a podcast or radio interview, at the same time without having to worry about the sound from the sides, as its strength lies in side noise rejection.
This polar pattern captures sound in a 360-degree radius, making the microphones equally sensitive to sound in all directions. The Omni microphone capsules function on the pressure principle and have a single side of their diaphragm that is open for external sound.
It is the most natural-sounding polar pattern and records sound without any added coloration or enhancement. They have no angles of decreased sensitivity and no null points, making them prone to feedback during live sound support situations. The best use of omnidirectional microphones is in the recording studios, radio broadcasts etc.
The diaphragm in microphones is a thin membrane or a tiny plate that moves when there is a movement in the sound pressure waves that strike it. It varies in size, determines the microphone’s capabilities, and is considered a critical element in microphones.
The movement of the diaphragm with sound pressure indicates the conversion of acoustic energy into electrical energy. Microphones get unique characteristics and sound from how well the diaphragm and capsule are constructed. These diaphragms are extremely thin and may be less than 5 microns in size. This thinness makes it extremely sensitive and forces it to move from the surrounding vibrating air molecules.
Small diaphragm microphones have a diaphragm diameter of lesser than .75 inches or smaller than 5/8″ and are good at capturing high-frequency details. They capture sound in its original quality without coloring or enhancing it. This happens due to the small diaphragm’s reduced diaphragm mass, which makes it more sensitive to air disturbances. Small diaphragm microphones can be used to record thorough audio details like the sounds of orchestral instruments, cymbals, bass guitars, and other small percussion instruments.
A medium-sized diaphragm microphone has a diaphragm size between 5/8′′ and 3/4′′ and attempts to capture the high-frequency range like a small diaphragm and deliver a warmer and fuller sound like a large diaphragm. These are hybrid mics, and you can use them in a variety of settings for recording vocals, podcasts, or even instruments like bass, keyboards, and guitars.
The large diaphragm microphones have a diaphragm size of more than 3/4 inches. These diaphragm sizes capture greater sound recording details at higher frequencies. They have a larger surface area, which makes them more sensitive to sound. These microphones can pick up the smallest of details and are used in studio recording settings. Thus, if you are a vocalist, you can give a large diaphragm microphone a good try, where some coloration and modification would bring no harm to the audio quality.
Specific Microphone Designs
Different microphones are made for different purposes. So, for example, you have a different mic for recording kick drums and a completely different microphone designed for home recording and podcasts. Likewise, something goes for the connecting ports. If you have something that only takes USB as input, you will have to look for a USB port microphone. Let us dive deep into the connectivity specifications.
USB Mics are audio transmitting and audio amplifying devices that could be plugged directly into the audio device as they need no extra equipment to function. These mics have built-in analog-to-digital converters, making it easier for you to plug them into your audio devices and get started with your projects.
They work like just another microphone that converts sound or mechanical wave energy into audio or electrical energy. These mics are a must-have to start passion projects for YouTube musicians and vloggers.
These mic designs do not have a physical cable to connect them to the audio amplifiers to which they are related. Wireless mics are condenser mics and work without external phantom power from a battery.
It can allow the user’s voice to transmit directly to the audio receiver attached to the system without a connecting wire or cable. They have a built-in transmitter that encodes the mic’s audio signal into the carrier signal, which is further transmitted wirelessly to the audio output. Try these wireless mics if you are Youtuber or an interviewer, or when you need a lot of movement while recording audio like live settings or speeches.
Boundary microphones are omnidirectional condenser microphones designed to be positioned near a floor or a wall. You can use them for office meetings, conferences, and theatre performances. You might have noticed them being placed on the meeting or conference room table. They come in different shapes and sizes. Some of them could be small microphones that you can place on the table, and they will be able to stand on their own. The basic idea is to record the sound or speech of all the people in the meeting room.
These mics are not affected by comb filtering, a phenomenon where the same sound is delivered to the listener’s ear at different times with a 15–20 ms delay in the audio signals. Thus, they are not affected by sound waves that reflect through walls and do not spoil the audio source.
Microphone Basics: Plosives And Sibilance
When trying to understand the basics of microphones, you should also be aware of some of the issues you could face while using the microphone. I will talk about a couple of sound issues, namely Plosives and Sibilance. Let me explain them one by one, and I will also suggest to you the ways that you can incorporate to avoid or overcome these while using the microphone.
Plosives are the sounds a speaker or a singer creates when pronouncing certain bass-heavy consonants like B, P, D, K, G, or T. The asymmetrical peaks and clips generated in the mic’s audio signals give out a windy or popping sound.
They need an extra blast of air from the lungs to generate windstorms at the front of the microphone. These sounds could ruin your audio quality and increase audio distortion. It is the overloading of a microphone’s capsule through extra air pressure originating at bass-heavy frequencies.
To avoid plosives, you should not place the mic directly in front of your mouth or position it “off-axis.” Another thing that you can try is to keep the mic a little above your mouth, and its tip (where you speak) should point in a lower direction. By doing so, there are high chances that you will be able to avoid any kind of plosives.
Sibilance is the high frequency of sound that creates a hissing sound when the letters S, Z, Sh, Zh, and T are used in vocal recordings by the artist. It lies in the frequency range of 5 kHz to 8 kHz. These sounds can affect your audio quality and cause harshness in the audio signal as the frequencies are unevenly represented on the mic signals.
You can reduce sibilance by recording on a ribbon dynamic microphone, giving you an accurate frequency response because of its darker color and controlled sensitivity levels. You can also stay at some distance from the microphone to minimize the effect of sibilance in your vocal recordings. Alternatively, you can position the mic’s angle at a certain angle so that your voice does not directly goes into the mic. If you think that using a pop filter may as well reduce the sibilance, then sadly, that is not possible.
I hope by now, you might have learned a few basic things and aspects of the technical jargon when it comes to choosing a microphone and using a microphone. If you feel that I have missed anything or want me to cover or add any specific topic, then you can drop a comment so I can include the same.
Frequently Asked Questions/FAQs
A good microphone for vocals should have a frequency range of 80 Hz to 15 kHz. Whereas, for toms and snares, look for lower frequency ranges below 50 Hz, and for recording drums and drum microphones with a frequency range lower than 40 or 30 Hz.
A microphone should be placed at an ideal distance of 6 to 12 inches from the mouth of the vocalist. This distance can keep your voice from sounding too deep or bassy.
You can know about your microphone’s quality by measuring its sensitivity. It is calculated by projecting a 94 dB SPL (1 Pascal) 1000 Hz tone at the front of the microphone capsule.
The diaphragm’s size affects the microphone’s quality. The larger the size of the diaphragm, the more audio data it can pick up, and the smaller the size of the diaphragm, the less audio data can be captured by the mic. Larger diaphragm microphones also allow for crisper and clearer audio quality.