Top 6 Things About USB Microphone
USB microphone, as the name suggesting, it is a microphone with a USB port. Essentially, USB microphone integrates USB sound card and microphone components together, through internal digital to analog conversion (AD) circuit, realizing microphone recording, live streaming and monitoring. When recording with computer or laptop, the microphone receives the sound, which is processed by the built-in sound card of the microphone, converts the analog signal into digital signal and transmits it to the computer/laptop in the form of lossless data via the USB interface.
In recent years, USB microphone is gradually favored by vloggers, video producers and recording enthusiasts because of its quality-clear audio, portability, plug-and-play and easy operation. If you intend to purchase a satisfying USB microphone, six things you need to know well about it.
Sensitivity refers to the ability of the microphone to convert sound pressure into levels. Generally speaking, the higher the sensitivity of the microphone, the better the level output. High-sensitivity microphones are helpful to pick up slight sounds and ensure low noise. There are two kinds of microphone sensitivity units: mV, referring to the sound pressure measured at 1kHz per Pascal. dB-taking 1V/Pa as the measurement condition, and the sensitivity is negative.
Sampling rate, also known as sampling speed, means the times that the microphone sound card records sound waveform in one second. Sound output through the microphone is usually at half the sample rate, so double the sample is needed to reproduce the sound. Hence, the higher the sampling rate, the clearer the recorded sound quality will be. For example, the frequency of human speaking is about 10KHz, so the sampling rate needs to take 22KHz.
It refers to microphone’s ability to convert sound signals into electrical signals whether they are fidelity or rendered for input. Generally, human can receive the frequency response range between 20Hz and 20KHz, which is full sound range of high fidelity. The wider the microphone frequency response, the stronger the human voice reception, but meanwhile the problem is the quality of the sound processing, so the wider the frequency response is not the better.
The sound of 20Hz-20KHz frequency response shows features: flat, natural and rising at the high frequency, which means the sound is crystal-clear.
RODE NT-USB MINI ’s frequency response image
Signal-to-noise ratio (SNR) is the ratio of the output signal power of a microphone to the noise usually expressed in decibels(dB). Usually, the higher the SNR, the less noise is mixed in the signal, and the higher the quality of sound playback, and vice versa. For a good quality microphone, SNR should not be less than 70dB, high fidelity USB microphone SNR even more than 110dB.
Sound pressure level (SPL.) refers to the maximum steady stat ability of sound pressure that the microphone can bear. The sound pressure capacity of the microphone is an important factor to consider when recording. Because sound pressure comes with total harmonic distortion (THD). In the ordinary way, the sound pressure overload of the microphone is easy to cause sound distortion, and the higher the sound pressure level, the less distortion of the human voice.
Commonly, the maximum SPL of ordinary microphones is limited to 126dB. However, AKG Perception-P220 USB microphone has a switchable level attenuator which allows the microphone to withstand up to 155dB SPL. This performance expands its practical application.
Polar pattern is the microphone’s description of the sound sensitivity patterns from all directions in space. Generally, there are two kinds of polar patterns for USB microphone: omnidirectional and cardioid pattern.
Omnidirectional microphone can pick up sounds from all directions equally. The other characteristic is that it won’t change the voice features because of distance changes. It is suitable for sound source movement or collecting environmental sound. The disadvantage is that it is easy to be disturbed by environmental noise. Omnidirectional microphone is often used in public speaking such as conference and seminar.
Cardioid microphone has best pickup effect to sounds from the front of the microphone and sounds from other directions will be attenuated. It is suitable for multiple recording environments, especially when lots of ambient indoor sounds need to be removed, such as speech, video teaching, live-streaming. Hypercardioid microphone has narrower directivity than cardioid ones, especially suitable for picking up sounds at close range and live recordings that require isolation.
Some high-end USB microphones are equipped with two polar patterns which can be selected according to actual requirements, such as COMICA STM-USB, Blue Yeti Nano. Some even have four polar patterns for choice like BOYA BY-PM700.
Comparison of several USB microphones on the market:
|MOMAN EM1||RODE NT-USB Mini||BLUE YETI||AKG Perception-P220|
|Sensitivity||-45dB+3dB re 1 Volt/Pascal||/||4.5mV/Pa||20 MV/PA (-34 dBV)|
|SNR||/||/||/||78 dB(A), Re 1 PA|
|Maximum SPL||/||121 dB SPL (1% THD)||120 dB SPL (0.5% THD)||Without Pad: 135 dB (0.5% THD)
With Pad Engaged: 155 dB (0.5% THD)
|Polar Pattern||Cardioid||Cardioid||Cardioid, Figure-8, Omnidirectional||Cardioid|
When choosing a USB microphone, it is necessary for you to make a budget plan as well as firstly realize your actual applications. Most of basic USB microphones can satisfy your needs of online lesson, gaming and video chat.
If you use it for computer recording, dubbing commentary and have certain requirements to sound quality, you need to really understand how the parameters aforementioned affect the sound quality.
If you are planning to do professional recording, broadcasting, or instruments recording, some advanced functions of high-end USB microphones should be taken into considerations, such as real-time monitoring, sound card effect, ASIO etc.
Therefore, it’s important to choose the most suitable one for yourself so that it can bring out the best sound quality in your recording.