Headset microphone

Goto sound properties by right clicking your speaker icon, recording settings, click line in. Line in properties, Levels and turn up and make line in your default for the microphone.

i have a inspiron14 3421 laptop. my headset microphone not recognize.when i connect my headset to 3mm port

Hello. First make sure that your headset has a 4 segmented plug (TRRS). A headset with  3 segmented plugs (TRS) will not work with the combo jack on the Inspiron 14 3421.

Also make sure that your Realtek audio driver is installed. You can use either the native windows audio driver or the manufacturer's driver, but often laptop mic jacks do not work properly with the native driver. Go to the Inspiron 3421 downloads page and select your OS in the box (7, 8, or 8.1), then expand the audio category and download the Realtek driver there.

Open the Recording tab of the Sound properties. It should say "Microphone -- Realtek High Definition Audio". Right click on that to open the context menu, then click "Properties".

In the mic properties, select the "Levels" tab to set your mic boost and gain levels.

When you plug in your headset with the TRRS plug, the jack is supposed to detect the mic and switch from the internal mic to the jack mic. On the "General" tab of the mic properties, it should change from ATAPI Internal jack to 3.5mm jack or something like that.(Note that it won't change while the properties box is open -- close or re-open properties to see any changes).

If that does not happen then there might be a problem with the jack sensing. Try a different headset if possible. If nothing works then you might have to Contact Technical Support 

Edit: with some Realtek drivers there is a setting that can be useful, but I don't know if your version of thedriver has it or not. Go through the Control Panel and open the Realtek Audio Manager (on Dell laptops it is often named the "Dell Audio Manager"). Click the button for Advanced settings. Put a check next to "Separate all input jacks as independent input devices". If you have that setting then when you open the Recording tab of the Sound properties, the internal mic and the jack mic show up separately, which allows you to manually select the jack mic as the default device.

and make line in your default for the microphone.

Thanks for posting on the Laptop Audio board. Just want to mention on the Dell laptops like the Inspiron 3421 with only a single combo jack (which combines both headphone and mic inputs into a single TRRS jack socket), line-in is not supported. Combo jacks only support mono mic input.

On Dell laptops where line-in is supported, "microphone " should be selected for mics. Line-in is for stereo line level input and does not provide the mic boost function that mics usually require. But if the mic is plugged into a hardware mic pre-amp and the pre-amp is plugged into the laptop, then line-in would be selected.