This calculator turns the raw figures on a microphone spec sheet into the numbers that actually matter for quiet recording: signal-to-noise ratio, dynamic range, the minimum detectable sound level, and the absolute output voltage of the noise floor. Enter the values once and compare any two microphones objectively.
How it works
Microphone specifications reference everything to 94 dB SPL, which equals one pascal of pressure at 1 kHz. The signal-to-noise ratio is simply how far the self-noise sits below that reference:
SNR (dB) = 94 − equivalent self-noise (dBA)
Dynamic range (dB) = max SPL − equivalent self-noise (dBA)Sensitivity in dBV/Pa gives the output voltage for a 1 Pa signal (using
V = 10^(dBV/20), where 0 dBV = 1 V RMS). The noise-floor voltage is that
reference voltage divided by 10^(SNR/20), which is why low-noise mics can have
a noise floor of only a few hundred nanovolts.
Example and tips
A microphone rated at 14 dBA self-noise, −37 dBV/Pa sensitivity, and 134 dB max SPL gives an 80 dB SNR, a 120 dB dynamic range, and a minimum detectable level of 14 dB SPL — roughly the threshold of a very quiet recording booth. When comparing microphones, the self-noise figure is the single most useful number for quiet work; the SNR is just the same information expressed against the 94 dB reference. A-weighted (dBA) and CCIR-weighted noise figures are not directly comparable, so make sure both mics quote the same weighting before judging.
Practical benchmarks for choosing a microphone
Knowing the raw dBA figure is useful, but the context matters:
| Self-noise (dBA) | SNR | Typical application |
|---|---|---|
| Below 7 | Above 87 dB | Nature recording, pianissimo classical, acoustic research |
| 8–12 | 82–86 dB | High-end studio work, acoustic instruments, overhead drum mics |
| 12–18 | 76–82 dB | General studio recording, podcasting, voiceover |
| 18–26 | 68–76 dB | Live sound, broadcast, interview work |
| Above 26 | Below 68 dB | Close-miked loud sources, instrument amps, not ideal for quiet sources |
Note these are rough practical ranges, not strict standards. Room noise, preamp noise, and acoustic treatment all interact with the microphone’s self-noise to set your actual noise floor.
Self-noise vs. preamp noise
A microphone is only half the chain. A quiet mic paired with a noisy preamp can easily produce a noise floor higher than either component’s specification implies, because the preamp’s equivalent input noise (EIN) adds to the signal. When the microphone’s output voltage is very low (low-sensitivity mics at quiet sources), preamp noise becomes dominant. The sensitivity figure this tool computes in millivolts helps you see how large a signal the microphone presents to the preamp — the quieter the source and the lower the sensitivity, the more important a low-EIN preamp becomes.
A note on weighting curves
Spec sheets sometimes quote noise in unweighted dB SPL, A-weighted dBA, or CCIR-468 dBr. A-weighted figures are the most common and match how the ear perceives mid-frequency noise. CCIR-468 weighting emphasizes higher frequencies and tends to produce numerically larger figures for the same noise, so a microphone specced in CCIR-468 will appear noisier than one specced in dBA even if their actual noise floors are similar. Always use the same weighting when comparing two microphones in this calculator.