Timeline for how to find frequency response of microphone
Current License: CC BY-SA 4.0
19 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| May 12, 2021 at 20:10 | vote | accept | SeAlGhz | ||
| Feb 24, 2021 at 9:00 | history | tweeted | twitter.com/StackSignals/status/1364500323784654851 | ||
| Feb 19, 2021 at 16:03 | comment | added | Hilmar | I certainly would NOT consider an ADMP401 as a reference microphone for anything but that really depends on the requirements for your application. | |
| Feb 19, 2021 at 14:27 | comment | added | jojeck♦ | Let us continue this discussion in chat. | |
| Feb 19, 2021 at 14:26 | comment | added | SeAlGhz | @jojek I intend to use ADMP401 as my reference microphone. do you think that it is accurate enough? my test microphone is cheap, chines microphone n and without any datasheet. thanks | |
| Feb 19, 2021 at 14:18 | comment | added | jojeck♦ | Yes. As long as it's not too loud (causes clipping/distortion) or too quiet (drowns in the self-noise) then you will be fine. Usually, when I am working with cheaper speakers, I would play the sweep at 74 or 84 dB SPL and scale the result. No need to drive it so loud. And like I said before, make sure that you know the level for 1kHz , other frequencies don't matter - you will get offsets from the frequency response. Even speaker doesn't need to be perfectly flat - you gonna remove its effect when subtracting the measurement of the reference microphone. | |
| Feb 19, 2021 at 14:12 | comment | added | SeAlGhz | @jojek u mean it doesn't matter which SPL level I use. I just need to be consistent with my level in all frequency ? | |
| Feb 19, 2021 at 14:04 | comment | added | jojeck♦ | So for example, if you measured the same microphone with 114 dB SPL, 1 kHz sine wave you would get 125.9 mV = -18 dBV. Then, in order to find the sensitivity, just subtract the difference between 114 and 94 (20), which will give you -38 dBV (12.6 mV/Pa). So, as long as you know the exact level of your excitation signal, you can easily calculate the microphone sensitivity. As for frequency response, it can be measured at any level. Some will graph it so that 1kHz is exactly at 0 dB, whereas others will shift it so that 1kHz is exactly at the dBV level equal to senstivity. It's all the same. | |
| Feb 19, 2021 at 13:58 | comment | added | jojeck♦ | Also, I think you might be confused. Sensitivity is measured for 1k sine wave @ 94 dB SPL (1 Pascal). So for analog microphones, this might give you values such as 12.6 mV/Pa, basically what's the voltage RMS when you expose the microphone to 1 Pascal of acoustic pressure. Alternatively, sensitivity can be represented in decibels relative to 1 volt (dBV). So the above example would become -38 dBV of microphone sensitivity. Now, the important thing is that you don't have to measure the sensitivity at exactly 94 dB SPL, in fact you can use other levels and simply scale the result. | |
| Feb 19, 2021 at 13:13 | history | edited | SeAlGhz | CC BY-SA 4.0 |
added 392 characters in body
|
| Feb 19, 2021 at 13:13 | comment | added | jojeck♦ | If you have a reference microphone then you can do it with substitution method, Did it myself many times. Preferably, you want to have a class-1 reference microphone and a way to record the signal off it via audio interface. First, place the ref mic close to the speaker and play the sweep (I suggest REW for that). Then remove the reference mic and in the exact same position place the unknown microphone. Measure with sweep again. Divide the two responses and you will end up with the response of your microphone under test. You can use any playback level. 94 is good for sensitivity at 1k. | |
| Feb 19, 2021 at 13:13 | comment | added | SeAlGhz | @MarcusMüller you can assume that I have a really precise reference microphone and I can find out the SPL of speaker by means of this reference microphone. I also don't really care about direction and distance because I use the reference mic so the only thing that matters to me is SPL. also assume that I afford very precise speaker too and don't care about it's response. I appreciate your help | |
| Feb 19, 2021 at 12:53 | answer | added | Hilmar | timeline score: 4 | |
| Feb 19, 2021 at 12:52 | comment | added | Marcus Müller | Is your speaker calibrated, i.e. do you know the speaker's frequency response? | |
| Feb 19, 2021 at 12:51 | comment | added | SeAlGhz | @MarcusMüller I'm sorry. I read the microphone output voltage. and I want to find the sensitivity in different frequency. | |
| Feb 19, 2021 at 12:49 | history | edited | SeAlGhz | CC BY-SA 4.0 |
added 58 characters in body
|
| Feb 19, 2021 at 12:47 | comment | added | Marcus Müller | I'd be surprised if your microphone gave you SPL – in that case, it would be a calibrated measurement microphone, and you'd already know the frequency response. | |
| Feb 19, 2021 at 12:35 | review | First posts | |||
| Feb 19, 2021 at 15:09 | |||||
| Feb 19, 2021 at 12:34 | history | asked | SeAlGhz | CC BY-SA 4.0 |