I have an Acer Aspire 5 laptop. On the side of the laptop, there is a 3.5mm jack. The icon next to the jack prints a headphone with a mic.

I tried plugging in an earpiece (with a TRRS plug) and I can hear stereo. But I don't see how I can use its mic.

I opened Sound Settings and under Choose your input device, there is only 1 option of Microphone Array (Realtek(R) Audio). If this laptop has an integrated audio jack, should I be seeing an additional input device? Or does the laptop not detecting a mic?

  • Would be good to see which exact icon you have next to the connector. Headphone and microphone or headset? It also worth checking your headset is completely connected. – Máté Juhász Apr 4 at 8:15

The easiest way is to check if your jack has the combo jack symbol (headphones with a mic aka headset) next to it like this.

Combo jack symbol

The Acer Aspire 5 has an integrated mic, so the way it works is whenever you plug into your combo jack your headphones with mic it will automatically recognize the new mic and turn off the integrated one. This is because the combo jack input is compatible with both TRS and TRRS and "tells" the difference as a consequence of physical contact (depending on what you plug in the jack which is on the motherboard, you'll get different impedance/resistance which translates to different voltages, from there the OS communicates with the drivers and has instructions on what to do depending on the readings).

enter image description here

If you have Windows OS you can always check if the mic has been detected by right clicking the speaker icon in the task bar/Click Sound/Click Recording. In here, simply tap your mic or make a sound and you should see these green bars.

example of Mic detected

Btw whether you have your headset plugged in or not, you'll ever see only the 1 mic device in the Recording tab (I literally just checked, and encourage you to try).

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    I am thinking along the same line too. But I have some doubts. Specifically, how would the laptop detect that I plugged in a TRRS plug instead of a typical TRS stereo plug? Typically, 3.5mm plug are detected mechanically when it is inserted. But to tell the difference between TRS and TRRS, it cannot rely on mechanical alone. – some user Apr 5 at 0:04
  • Actually, it does rely on "mechanical detection". The difference between TRS and TRRS is that TRRS has one more physical contact. TRS has 3 points of contact (Top, Ring, Sleeve) and 2 insulators (those 2 black lines), while TRSS has 4 points of contact (Top, Ring, Ring, Sleeve) and 3 insulators (3 black lines). Here, take a look at this image where all of the above is shown and also the purpose of each contact. – Drakkar Apr 5 at 4:41
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    If a TRS plug is used there will be no resistance between the ground and microphone conductor whereas there will be significant resistance if a TRSS plug is used. i.e. You can detect the TRS plug by asking "is the microphone line grounded?" – Alex Fitzpatrick Apr 5 at 17:42
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    Yes, the detection is a combination of both an electrical consequence (higher impedance resulting in higher resistance when the number of physical contacts and transmitted signal increases) due to what its plugged in the jack of the motherboard (hardware), and what/how the OS interprets (software) via communication with the drivers. – Drakkar Apr 5 at 17:55
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    I tried with another headset. That worked! I also tried another Lenovo laptop that runs the same Windows 10. On the Acer, it pops up a dialog asking me what I plugged in and I have to choose "Headset". On the Lenovo, there is no such dialog yet it automatically detected that I have plugged in something, AND if it has mic or not. The external mic will be grayed out if I plug in a headphone. – some user May 1 at 22:52

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