In this note, we are going to talk about the Microphone and Characteristics of Microphone. Welcome to Poly Notes Hub, a leading destination for Diploma Engineering Notes.
Author Name: Arun Paul.
What is Microphone ?
An apparatus or transducer that transforms sound waves into electrical impulses is called a microphone. It is made out of a membrane or diaphragm that vibrates in reaction to sound waves. When this happens, a coil or capacitor moves within a magnetic field and produces an electrical signal proportionate to the sound waves. This electrical signal can then be transmitted, recorded, or magnified to replicate the original sound. Microphones are employed in various settings, such as audio conferences, live performances, recording studios, and telecommunications.
Characteristics of Microphone
The characteristics are –
- Sensitivity
- Signal to Noise Ratio
- Frequency Response
- Distortion
- Directivity
- Output Impedance
1. Sensitivity
The ability of a micro-phone to convert sound pressure into an electrical signal is known as sensitivity. Typically, it is expressed in millivolts per Pascal, or mV/Pa, or decibels per Pascal, or dBV/Pa.
2. Signal to Noise Ratio
In the context of micro-phones, signal-to-noise ratio (SNR) is the ratio of the intended signal (the sound being recorded) to the undesired noise that is present in the output signal of the microphone. It is a measurement of the audio signal’s quality in relation to the background noise level.
Put otherwise, signal-to-noise ratio (SNR) measures the difference between the intended sound level and the noise produced by the microphone or external elements.
SNR is typically expressed in decibels (dB), with a higher value indicating a better signal-to-noise ratio. For example, an SNR of 60 dB means that the desired signal is 60 dB louder than the background noise present in the microphone’s output.
3. Frequency Response
A microphone’s frequency response, which is commonly expressed in Hertz (Hz), characterizes how sensitive it is to different frequencies that fall within the range of human hearing. It describes how uniform sound is reproduced by the microphone at all frequency ranges, from low to high pitches.
A microphone may record sounds from the lowest audible frequencies to the highest, for example, if its frequency response ranges from 20 Hz to 20 kHz. The microphone may, however, show differences in sensitivity at other frequencies within this range.
4. Distortion
Any modification or corruption of the original sound signal that takes place during a microphone operation is referred to as distortion in the microphone industry. The waveform or frequency content of the recorded sound is usually altered unintentionally as a result of this modification.
5. Directivity
A microphone’s sensitivity pattern, or directivity, describes how it captures sound from various directions about its placement. To put it another way, it shows which angles or directions the microphone can record sound from while attenuating sound from other directions.
Micro-phones can have various types of directivity patterns, including:
- Omni-directional
- Cardioid
- Super cardioid / Hyper cardioid
- Bi-directional
- Multi-directional
6. Output Impedance
The electrical resistance that an electrical signal experiences on its way from the microphone’s output terminals to the input of a later device—like a mixer, amplifier, or audio interface—is referred to as the output impedance in a microphone. Usually, it is expressed in ohms (Ω).
The internal circuitry of a microphone controls its output impedance, which varies based on the design and construction of the microphone. For the best signal transfer and the least amount of signal loss, the input impedance of the connected device and the microphone’s output impedance must match.
Impedance mismatch is a condition that can occur when the input impedance of the connected device is substantially lower than the output impedance of a microphone. Increased noise levels in the audio stream, loss of high-frequency responsiveness, and signal deterioration can all be brought on by impedance mismatch.