English 
Chinese Introduction: What Is Microphone Sensitivity and Why Does It Matter?
Microphones are pressure-sensitive transducers that convert sound waves into electrical signals. Sensitivity defines how effectively a microphone captures low-level sound pressure (SPL) and translates it into voltage (analog) or digital output. It is one of the most critical specifications when evaluating MEMS microphones for smart home, mobile, or industrial audio applications.
At Wuxi Silicon Source Technology Co., Ltd., we specialize in MEMS microphones designed for diverse voice interface scenarios—from near-field smart devices to far-field conference systems. In this blog, we break down how to interpret sensitivity specifications, compare analog and digital mics, and help you make the right choice for your design.
Defining Sensitivity: dBV vs dBFS
🔹 Reference Sound Level: 94 dB SPL
Most microphone sensitivity ratings are based on a 94 dB SPL input, which corresponds to a 1 Pascal pressure wave. This value is derived from:
dBSPL = 20 × log(P / P₀), where P₀ = 20 μPa
⇒ 20 × log(1 Pa / 20 μPa) = 94 dBSPL
Analog Microphone Sensitivity
Analog MEMS microphones express sensitivity in dBV/Pa, where 0 dBV = 1 V RMS output.
- Formula:
Sensitivity (dBV) = 20 × log10(Vout / 1 V) - Example: A mic with 10 mV/Pa output →
20 × log10(0.01 / 1) = -40 dBV
Analog mics benefit from front-end gain tuning. For instance, if an analog MEMS mic like the ADMP504 outputs 0.25 V peak, a 12 dB gain (×4) brings it to match a 1.0 V ADC full-scale input, preserving signal quality.
📌 Explore our analog MEMS microphone portfolio
Digital Microphone Sensitivity
Digital microphones measure sensitivity in dBFS (decibels relative to full scale).
- Formula:
Sensitivity (dBFS) = 20 × log10(Output / Full Scale) - Example: A digital mic with maximum SPL of 120 dB SPL and 94 dB SPL as the reference will have:
94 - 120 = -26 dBFS sensitivity
This represents the percentage of full-scale digital output produced by a 94 dB SPL input.
Key Limitation: Digital mics have fixed gain and sensitivity, determined by their internal ADCs and signal path. They are ideal for systems where consistent digital integration is required.
📌 Learn more about digital MEMS microphones
How to Choose the Right Sensitivity
Sensitivity is not a “higher-is-better” parameter—it depends on your application’s sound source distance and environment.
Near-Field Applications
(e.g., smartphones, earbuds)
- Use lower sensitivity to avoid clipping/distortion from loud, close-range inputs.
- Less need for amplification.
Far-Field Applications
(e.g., smart speakers, surveillance)
- Use higher sensitivity to capture attenuated speech.
- Requires good noise filtering to reduce interference.
Sound Pressure vs Distance Rule of Thumb
Every time the distance from the sound source doubles, the SPL drops by 6 dB. (Inverse-square law)
| Distance to Mic | SPL Drop |
|---|---|
| 0.5 m → 1 m | -6 dB |
| 1 m → 2 m | -6 dB |
| 2 m → 4 m | -6 dB |
Boosting Microphone Signals with Gain
Whether you’re working with analog or digital MEMS microphones, gain tuning is essential.
- Analog mics can use preamp stages to match system ADC ranges.
- Digital mics may need software-side digital gain (AGC) to align with downstream processing or voice recognition models.
📘 Also read: Microphone Array Beamforming for Smart Audio
Conclusion: Tailor Sensitivity to Application, Not Spec Sheet
Sensitivity is one of the most misunderstood microphone specs. Selecting the right value depends on multiple factors:
- Expected distance to sound source
- Noise floor of the environment
- System ADC or DSP chain
- Application: voice wakeup, far-field capture, or noise cancellation
At Wuxi Silicon Source Technology Co., Ltd., we help customers choose and integrate MEMS microphones with tailored sensitivity levels, ensuring clearer audio capture and better user experiences.
📩 Contact our engineering team for sensitivity tuning advice or custom microphone module development.
Internal Linking References
- Analog MEMS Microphones
- Digital MEMS Microphones
- Smart Microphone Modules
- Voice Recognition Applications
