Microphones Sensitivity Explained: dBV vs dBFS for Analog & Digital Mics

What is microphones Sensitivity?

microphones sensitivity refers to a microphones's ability to convert sound pressure into voltage or digital signals. Generally, the higher the sensitivity, the stronger the signal output by the microphones, meaning that the subsequent amplifier requires less gain.

The output voltage of a microphones per unit sound pressure level. Unit: millivolts per pascal (mv/Pa).

Core Definition and Technical Analysis of microphones Sensitivity

microphones sensitivity (Sensitivity of microphones) is a core parameter for measuring its sound-to-electric conversion efficiency, defined as the open-circuit output voltage of the microphones per unit sound pressure. When a sound pressure of 1 Pascal (Pa) (equivalent to a sound pressure level of 94 dB SPL) acts on the microphones diaphragm, the output voltage value (in millivolts, mV) is the sensitivity, with the standard unit being mV/Pa. This parameter directly reflects the microphones's response capability to sound signals: the higher the sensitivity, the stronger the ability to capture weak sound pressures; conversely, a higher sound pressure is required to produce an effective output. In professional acoustic measurements, recording production, and sound reinforcement systems, sensitivity is one of the key criteria for selection.

In-depth interpretation of sensitivity units: linear and logarithmic notation

Sensitivity is typically expressed in two forms: linear units (mV/Pa) and logarithmic units (dB). Linear units directly reflect the physical proportional relationship between voltage and sound pressure, for example, 10 mV/Pa indicates an output voltage of 10 mV at 1 Pa sound pressure. Logarithmic units are expressed in decibels (dB), with a reference baseline of 1 V/Pa (0 dB). The calculation formula is: SdB = 20 × log10(SmV/Pa / 1000). For example, converting 10 mV/Pa to logarithmic units: 20 × log(0.01) = -40 dB. Logarithmic representation compresses the numerical range, facilitating engineering comparisons and system gain calculations. The two units can be converted between each other, and professional equipment manuals often list both simultaneously.

Scientific methods and influencing factors for sensitivity measurement

Measurements must be conducted in a controlled acoustic environment such as an anechoic chamber: a standard sound source generates a 1kHz sine wave at 94dB SPL (1Pa), the open-circuit output voltage of the microphones is recorded, and the ratio is calculated to obtain the mV/Pa value. Measurement accuracy is affected by environmental noise, sound source stability, and circuit impedance matching. Sensitivity is not an isolated parameter; its actual performance is strongly correlated with the following factors:

Transducer principle: condenser microphones (including electret microphones) have thin diaphragms and are sensitive to electric fields, resulting in sensitivity values typically ranging from -40 dB to -30 dB (10 to 30 mV/Pa). dynamic microphones, which operate based on electromagnetic induction, have lower sensitivity values (-60 dB to -50 dB, approximately 1 to 3 mV/Pa).

Physical size: Large-diaphragm microphones have a larger sound energy capture area, resulting in higher sensitivity, making them suitable for detailed recording; small-diaphragm microphones are better suited for high-sound-pressure environments.

Circuit design: Electret microphones with built-in JFET amplifiers can enhance output, but it is important to note that fluctuations in supply voltage can significantly alter sensitivity.

Typical correlation between microphones types and sensitivity performance

Condenser microphones (including electret) are preferred for vocal and instrumental recording in studios due to their high sensitivity (-40 dB to -30 dB) and flat Frequency Response, particularly excelling in capturing weak sound sources. However, high sensitivity also makes them susceptible to wind noise and airflow disturbances, necessitating the use of a windscreen.

Dynamic microphones, with their lower sensitivity (-60 dB to -50 dB), excel in live performances and high-pressure environments: they are less prone to distortion from large dynamic signals and have a robust, impact-resistant design. For example, vocal microphones at concerts must withstand the high sound pressure generated by the proximity effect.

Aluminum ribbon microphones, though the least sensitive and most fragile, offer superior transient response and are indispensable in specific professional recording scenarios (such as brass instruments).

The dialectical relationship between sensitivity and signal-to-noise ratio (SNR) and application strategies

While high-sensitivity microphones can enhance signal gain, they may also amplify circuit noise and environmental noise, leading to reduced SNR. For example, in a noisy conference room, a -35dB microphones may produce clearer speech output than a -28dB model, as the latter is more prone to picking up background interference such as air conditioning noise.

Professional selection requires balancing scene requirements:

Low-noise environments (recording studios, anechoic chambers): Prioritize high-sensitivity + high-SNR microphones to maximize signal detail reproduction.

High-noise environments (stages, outdoors): microphones with medium to low sensitivity can suppress background noise, and directional designs (such as supercardioid) can further improve the signal-to-noise ratio.

Note: SNR is defined independently of sensitivity and reflects the ratio of the output signal to inherent noise (in dB), while the EIN (equivalent input noise) parameter provides a more intuitive assessment of the microphones's minimum measurable sound pressure level.

microphones sensitivity application strategies in professional fields

microphones sensitivity selection for recording must match the characteristics of the sound source. When recording acoustic instruments like classical guitars, condenser microphones with high sensitivity (e.g., -32 dB) can capture string overtones; however, for electric guitar amplifier pickup, dynamic microphones (e.g., SM58, -54.5 dB) are needed to avoid overload. In close-talking scenarios (such as podcast voiceovers), note that high-sensitivity microphones are prone to “popping” sounds caused by mouth airflow. It is recommended to use a pop filter or select a model with moderate sensitivity (-42 dB to -38 dB).

At the system integration level, sensitivity directly affects preamplifier gain design. For example, a -50dB dynamic microphones requires approximately 10dB more gain than a -40dB condenser microphones. If the mixing console's gain margin is insufficient, it will limit the dynamic range. Digital microphones have a uniform sensitivity of -26dBFS (at 94dB SPL), with full scale corresponding to 120dB SPL. Ensure that the rear-end ADC dynamic range is matched.

Detailed Explanation of dBV and dBFS in Analog and Digital microphones

When selecting a microphones, sensitivity is a very critical technical parameter. It helps you assess the microphones's ability to convert sound signals into electrical signals. However, many users are confused by the units of sensitivity, particularly the difference between dBV used for analog microphones and dBFS used for digital microphones.

Analog microphones: Sensitivity Expressed in dBV

For analog microphones, sensitivity is typically expressed in dBV (decibels relative to 1 volt). This unit indicates the voltage output of the microphones under standard test conditions.

For example:  

If an analog condenser microphones has a sensitivity of -40 dBV, it will output approximately 10 millivolts (mV) of voltage at 94 dB SPL.

The closer the value is to 0, the higher the sensitivity; the more negative the value, the lower the sensitivity.  

High-sensitivity analog microphones are suitable for quiet environments such as recording studios and vocal recording;  

low-sensitivity microphones are more suitable for high-sound-pressure environments such as drum kits and guitar amplifiers to prevent overload distortion.

Digital microphones: sensitivity expressed in dBFS

With the development of digital audio devices, digital microphones (such as MEMS microphones) are becoming increasingly common, especially in smart speakers, headphones, and IoT devices. The sensitivity of such microphones is typically expressed in dBFS (decibels relative to full scale).

0 dBFS represents the maximum output value of the digital system, and any sound below this value is represented as a negative number.  

For example, a digital microphones outputs -26 dBFS at 94 dB SPL, meaning its digital signal strength is 26 dB lower than the system's maximum value.  

This representation allows engineers to directly assess the dynamic range of the digital signal without considering the effects of preamplifiers or voltage changes.

Can dBV and dBFS be directly compared?

No. Because they belong to different signal processing stages:  

dBV is a measure of analog signal voltage  

dBFS is a measure of digital signal amplitude  

To make an effective comparison, you must know the ADC (analog-to-digital converter) resolution, bit depth, and whether additional gain adjustment has been applied.  

This is particularly important for professionals involved in hardware design, embedded development, and audio engineering.