What is microphone application?

A microphone is a transducer that converts sound waves into electrical signals. The first microphone was invented in 1876 by Emile Berliner and was originally called the “transmitter”. Microphones enabled the telephone and recorded audio to be developed. Over the years, different types of microphones have been created to capture sound in new ways for various applications.

Microphones work by having a diaphragm that vibrates in response to sound waves. This vibration is converted into an electrical signal via electromagnetic induction, capacitance change, or piezoelectricity. The electrical signal can then be amplified, recorded or transmitted.

Some key developments in the history of microphones include the carbon microphone in 1878, the condenser microphone in 1916, the dynamic microphone in 1923, and the electret condenser microphone in 1962. Today, microphones are used in many devices including phones, hearing aids, and for recording music and speech.

In summary, a microphone converts acoustic sound waves into an electrical signal by having a diaphragm that vibrates in response to the sound waves. This allows microphones to capture and transmit sound.

Types of Microphones

There are three main types of microphones: dynamic, condenser, and ribbon mics. Each type has different audio properties and ideal usage scenarios.

Dynamic microphones work by having a diaphragm attached to a coil of wire suspended in a magnetic field. When sound hits the diaphragm, it causes the coil to move up and down, generating an electrical current. Dynamic mics are known for their durability, versatility, and ability to handle high sound pressure levels. They excel at picking up loud instruments like drums and guitar amps. Popular dynamic mic models include the Shure SM57 and Sennheiser e835.

Condenser microphones require external phantom power to operate. They use a thin conductive diaphragm that sits very close to a metal backplate, forming a capacitor. When soundwaves hit the diaphragm, it moves closer and farther from the backplate, generating a voltage. Condensers are extremely sensitive and accurate, ideal for vocals, acoustic instruments, and overhead drum recording. Popular condenser models are the Neumann U87 and AKG C414.

Ribbon microphones work by suspending a thin corrugated metal ribbon between magnets. The ribbon vibrates when hit by soundwaves, disrupting the magnetic field and inducing a current. Ribbons have a smooth, natural sound great for guitars, drums, and vocals. Well-known ribbon mics include the Royer R-121 and AEA R84.

Microphone Polar Patterns

A microphone’s polar pattern indicates how sensitive it is to sounds arriving from different angles. There are several common polar patterns:

Omnidirectional

An omnidirectional microphone picks up sound equally from all directions. It has a spherical polar pattern and is sensitive to sound from 360 degrees around the mic (Lewitt). Omnidirectional mics are good for recording in reverberant spaces or multiple sound sources.

Cardioid

A cardioid mic is most sensitive to sounds directly in front, and less sensitive to sounds from the sides and rear. It has a heart-shaped polar pattern covering about 110 degrees in front of the mic (StudioBinder). Cardioid mics help isolate sound sources and reduce background noise.

Bidirectional

A bidirectional mic picks up equally well from the front and rear, but rejects sounds from the sides. Its polar pattern is spherical from front to back. Bidirectional mics are sometimes used for interviews with two people.

Shotgun

Shotgun mics have a very narrow polar pattern concentrated in one direction. They focus on picking up sounds directly in front and heavily reject off-axis sounds. Shotguns help isolate distant sound sources.

Microphone 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 of a microphone indicates the lowest and highest frequencies that it can detect and output with an acceptably high volume and accuracy (Shure).

The standard frequency range for most microphones is 20 Hz to 20 kHz, which covers the spectrum of audible sound for humans. However, some mics may have an extended or more limited frequency response beyond this range (Audio-Technica). The optimal frequency response depends on the intended application.

For example, vocals and speech mostly occupy the 200 Hz to 8 kHz range. Thus, microphones meant for singing or podcasting may prioritize an even frequency response in this range. On the other hand, drum overheads require a flatter, extended frequency response to capture the full spectrum of cymbals, drums and percussion.

When examining microphone specs, frequency response is typically plotted on a graph with frequency on the X-axis and volume level in decibels (dB) on the Y-axis. This shows the mic’s sensitivity across different frequencies. A flatter line indicates a more even response, while spikes or dips reveal boosted or attenuated frequencies.

Microphone Sensitivity

Microphone sensitivity refers to how well a microphone converts sound pressure into an electrical signal. It is typically measured in decibels relative to one volt per pascal (dBV/Pa) or millivolts per pascal (mV/Pa). A microphone with higher sensitivity produces a stronger electrical signal from the same sound source.

Sensitivity directly impacts the quality of the audio a microphone can capture. More sensitive microphones can pick up subtler nuances and quieter sounds. However, extremely high sensitivity can also lead to issues like background noise and distortion from loud signals overloading the capsule. There is a balance between achieving good signal levels while avoiding noise and distortion.

For general vocal and instrument recording, sensitivities between -46 dBV and -35 dBV (5.0 mV/Pa to 17.8 mV/Pa) are considered ideal. Within this range, condenser microphones tend to be the most sensitive while dynamic microphones are less so. ribbon microphones can have sensitivities as low as -60 dBV. Understanding a microphone’s particular sensitivity rating helps determine if it is appropriate for the desired source and use case.¹

Microphone Impedance

Impedance is a measure of electrical resistance in a microphone or audio system, measured in ohms. It affects how sensitive the microphone is to incoming audio signals. Microphones typically have low impedance, less than 200 ohms. Low impedance allows microphones to deliver stronger signal to the next component, like a preamp or mixer.

Higher impedance microphones, around 1000-6000 ohms, are more sensitive and tend to have a flatter frequency response, but also deliver a weaker signal. The tradeoff is that high impedance mics pick up more subtle nuances, while low impedance mics create stronger signals.

Typical dynamic vocal microphones have impedance between 150-600 ohms. Condenser microphones are available in a wider range from 100 ohms up to 10,000 ohms. Ribbon microphones also tend to be higher impedance, often above 250 ohms.

It’s important to match the impedance of the microphone, cable, and other equipment like preamps and mixers. Large mismatches can cause distortion, reduced signal levels, or other issues. Transformers can be used to convert between high and low impedance if needed.

Sources:

[What is Impedance? – Neumann Homestudio Academy](https://www.neumann.com/en-en/homestudio-academy/what-is-impedance/)

[Microphone Impedance – How does it matter?](https://intshop.jzmic.com/blogs/blog/microphone-impedance-how-does-it-matter)

Microphone Outputs

Microphones have different types of outputs to connect to other devices like mixers, audio interfaces, phone systems, and more. Some common microphone output connections include:

• XLR – The XLR connector is a standard 3-pin connection used on most professional microphones. It provides a balanced signal that helps reduce noise over long cable runs. XLR connections lock securely in place.
• USB – USB microphones plug directly into a computer’s USB port for easy connectivity. No additional audio interface is required. However, USB mics are limited to computer use.
• TRS (Tip Ring Sleeve) – The TRS connector is a 1/4″ or 3.5mm jack that carries a balanced mono signal. It’s less secure than XLR but used on many consumer mics and headphones.
• Wireless – Wireless mics transmit a signal over radio frequencies to a receiver unit, avoiding cables altogether. However, they may suffer interference and need batteries or charging.

XLR and TRS provide the most secure connections and best audio quality overall. USB microphones are incredibly convenient for recording into a computer. Wireless mics enable free movement. The right connector for the mic depends on the intended use and setup.

For more information, see:
https://en.wikipedia.org/wiki/Microphone_connector

Microphone Placement

Proper microphone placement is crucial for capturing the best sound quality during recording. The position and angle of the microphone in relation to the sound source can dramatically affect the tone, clarity, and character of the recording.

One key factor is the proximity effect, which causes enhanced low frequency response when the microphone is placed close to the sound source. Placing a microphone closer will create a warmer, booming tone, while more distance creates a thinner, brighter sound. Finding the ideal distance helps balance proximity effect and avoid plosives on vocals or boomy bass (Sweetwater).

Angling the microphone can also shape the tone and adjust room ambience being picked up. Pointing the mic directly at the source gives a more direct, dry sound, while angling off-axis warms up the high end and captures more room reverberation. Consider angling to avoid unwanted bleed from other sources

The recording environment also impacts optimal placement. In a professional studio, mics can be placed closer to isolated sources without bleed. Live sound reinforcement requires more distance and strategic angling to minimize feedback. Outdoor recording needs to account for wind noise. Adapt placement as needed for the recording situation.

With attention to proximity, distance, angle and environment, proper microphone placement captures the intended sound character and optimizes recording quality.

Microphone Applications

Microphones are used in many different applications to capture and record audio. Choosing the right microphone for the application is important for capturing optimal sound quality.

Vocals

For recording vocals, condenser microphones are a popular choice as they provide detailed and accurate representation across the frequency spectrum. Some popular condenser mics for vocals include the Shure SM7B, Neumann U87, and Audio-Technica AT4040.

Instruments

When recording instruments like guitar, drums, and piano, dynamic microphones are often used. Dynamics handle high sound pressure levels well. Popular choices include the Shure SM57 for instruments, Shure SM7B for vocals, and AKG D112 for bass drum.

Podcasts

For podcasting, studio condenser microphones provide excellent speech intelligibility. The Electro-Voice RE20 is a standard dynamic podcast mic, while the Blue Yeti is a versatile USB condenser mic.

Field Recording

Portable condenser microphones are ideal for field recording applications like interviews and capturing ambient audio. The Shure VP83F and Zoom H5 are popular options that provide excellent sound quality in a compact form factor.

Microphone Accessories

Microphone accessories help improve sound quality and make using microphones more convenient. Some essential accessories include:

Pop Filters – Pop filters are screens placed in front of a microphone to protect against plosives or pop sounds caused when saying words with hard consonants like “p.” Pop filters improve audio quality by reducing harsh popping sounds. According to Amazon, pop filters are an “essential studio recording microphone accessory” (1).

Shock Mounts – Shock mounts suspend microphones and isolate them from vibrations. This prevents rumbling noises caused by bumps to mic stands or surfaces. Shock mounts often connect to microphone stands for optimized positioning. Sweetwater recommends shock mounts as an essential microphone accessory (2).

Microphone Stands – Stands provide adjustable and stable mounting options for microphones. Floor stands, tabletop stands, and boom arms allow optimal microphone positioning. Using a quality stand improves audio by reducing vibrations.

Windscreens – Windscreens or windshields protect microphones from wind interference and “p” popping. They easily fit over most mics. Windscreens improve sound quality for outdoor recording or close vocal miking.

Other useful accessories include mic clips, cables, carrying cases, and stereo bars for capturing ambient audio. With the right accessories, microphones can be set up for professional quality audio in any recording scenario.

(1) https://www.amazon.com/Microphone-Accessories/b?ie=UTF8&node=8882490011

(2) https://www.sweetwater.com/shop/studio-recording/microphones/accessories/