NO SOUND?  NO AUDIO?        
          

  • My internal speakers are dead (Laptops) 
  • The Desktop external speakers are dead using the green 3.5mm jack on the PC. (or just unplugged or 1/2 plugged in, or power the speakers is missing or not plugged in or this)
  • My Ear-buds are dead. (way more serious this, and 2 times more worse if Windows sounds are dead) See drivers here.
  • My real head phones , real means actual phones with a 3.5mm green phone plug (not USB head-phones, I do not cover USB phones here)
I will cover only dead 2 channel Stereo sound channels, not 5.1/6.1/7.1 quad sound or the like here nor optical jacks of any kind. (just simple basic sound) Basic, simple and cheap sound.(local chip only)
This page covers only the on-board, sound chip or sound card option, in your PC, to test that, remove all USB devices and Bluetooth devices, first related to sound.  (see my NOT COVERED box here.
On-board means the sound chip is found on the main motherboard, ADD IN boards are called PCIe sound cards.(and are added later in many cases)
There are 1000s of sound chips made, learn that guessing which one is futile. (Plug and Play if not dead , most times, finds it , loads it and like magic just  works ok)
The sound chips inside any PC are known for there poor and noise ridden sounds, (computers clocking noises endless) The cure is using a USB DAC box ! (digital to analog converter box)
See the magic of PCI-z scanner tool, get it run it and see what is really inside that boxed PC.

Sounds started in 1989 (called by the fancy name "multimedia" ) with the mighty Sound blaster 1.0 card, in desktops.
Sounds must be tested from simple modes to complex, first.  (windows sounds 1st,  local sound files play ok and last internet sound or Video of any kind (most complex of all)

First off , if it's a laptop, the inside speakers almost never fail for sure both at once, how could they "?  (some desktop SFF boxes have speakers in side too, RTM read the manual or look inside)
? but the ear phone jack can fail (dirt in its hidden inside switch) and kill the internal speakers dead super easy, cycle that phone jack with a plug in set of buds to free this jam.
I will attempt (sorry if I fail)  to put jump logic in my list below, for Jumps on Desktops (desktops can have like 1000 different sound cards inside)
Let me do a simple bullet list  for the silly things that fail first.  (when I say green jack that means the actual green desktop jack, but on silly laptops, it has no green mark there, (only labeled as phone/ icons as a clue)
  • Turn the MUTE button off, in the task bar is it,  if yes click it off.   right click it to turn up volumn and turn off MUTE.
  • The rear of the PC has  green jack, (or marked as phones or line-out) Your earbuds, head phones or speakers must be connected here to get sounds, unless a  laptop with internal speakers.
  • The USB jacks must not have any USB head phones plugged in now. (to make those rascals  work right, can be a long long hard process, ask the maker of said Phones , how to make them work.(only they know  how)
  • If said sound devices, are external speakers, they must be turned on, (AC  powered they are) and must have there independant sound controls turned up. Or there will be no sound from them. (and connected to the green jack)
  • The best testing  device for sounds are $1 dollar store EAR BUD phones,  (dirt cheap and always work and always my first tests besides mute and volumn wrong.)
  • The External speakers in desktops can be hidden inside MONITORS, connected the same way but now you must use  the monitors OSD  menu button and turn up volume inside that window.  (varies by make of monitor the steps , RTM (read the manual)
I simply click the taskbar Icon, and turn off mute and then up the volume, example here is W10.  Speaker Icon here is dead or missing acts odd the sound driver is bad.

The next thing to check is the MIXER.
Do I need to say if the earbuds worked ok, above,  then sounds are ok!, only the actual speakers are dead? external?
If this is a laptop and the earbuds work then your PC needs service,  The jacks can be bad , there is switch inside the jack that switches, Buds or internal ( line_out or internal to be technically accurate) Even cycling the earbud into said jack can fix this.
Some PC have  2 line-out( phone out , speakers out ) jacks, front and rear. Try them both, and know too that if the motherboard connectors to both jack panels can fall off and it it does both panels can fail. (jack panels)
Some desktops monitor the front panel and if the panel lies (logic) the rear goes dead, because it thinks (wrongly) your front panel has plugged in, say speaker or phones and are not plugged in, so look inside the Desktop for those wired connectors , Fell OFF.
This is tricky business here, so I will stop, at deeper hardware analysis and just cover the common easy sound failures, end to ead, the 99% most common, not dead chips.


The order of these tests are important (it's progressive) (all sounds originate from a Digital files somewhere ;anywhere) Windows sounds are  xyz.wav files.  (located in the Windows folders)
Testing 1,2,3:
  1. Next check your MIXER see first in photos below, (turn all that up, and the speaker ICON to selected now) See the first photo below for mixer settings.
  2. Try $1  Ear-buds next in the desktops the jack is GREEN (means LINE OUT to speakers or phones) does that work, lets say no. ( see my buds?)
  3. If Ear bubs work then you do have sound, only the speakers are dead, on  most Desktops ,speakers are in fact an option, and must be plugged in correctly to the green "Line_out" jack.  If External speakers fail, jump here.
  4. Ok buds are dead,  next is control panel, click start, and find and click   control panel (CP), as seen in Photo1 below.
  5. Next click SOUND on that CP window. Photo1.
  6. Open the SOUNDS tab. see  Photo #2
  7. Click Asterisk choices, and push the TEST BUTTON, if this fails windows sounds are dead, try other choices there, pick critical STOP error. (this must work)) if not, jump to 10. If OK then see line 17
  8. Go to CP again, (control panel photo1) and pick Device Manager {DM}, See photo 3 below and this is what you may see.
  9. On the left side of DM are all the chips in your PC, called DEVICES. See the line called SOUND, the chips there must not be missing , in RED/yellows error marked or show as UNKNOWN if yes, see end of this page (NODRIVER.)
  10. Just because DM shows no errors, there, this only about 75% accurate, so do the right click SOUND, and  update driver. (you must be internet connected here or 1/2 your changes fail here)
  11. On some Desktops, you may have 2 sound chip devices, the onboard, sound chip and or just PCI slot Sound card,  (Creative labs or 1000s of others made and sold and installed) Only you know which chip is is best for you. 
  12. The PCI slot sound card is usually the best for sound,  and on old PCs, you must go into the BIOS and disable the on motherboard (mobo) chip or sounds can fail,  if newer PC this is Automatic this swap over from onboard to PCI sound slot sounds.
  13. Click DM VIEW tab, click hidden devices, I bet now that the dead device shows up, and failing , but   still missing, you need to go in to BIOS and see if the brat kids disabled sound in BIOS,  (jump to photo below.)
  14. If the BIOS shows sound is enabled, run the PCI-Z program next (application/app) run that and see all chips and what sound chips are there, makers name "eg. Realtek" and model ACL221 or 880 / 888/892/8111/8139 and lots more some not supported
  15. I know for a fact some very popular Realtek sound chips are not supported in W7,  installed with a Microsoft install DVD or ISO.  (but available from HP or DELL or Realtek, or your PC makers home pages)
  16. If you can, click the named sound chips name on the left DM, called selecting in Windows. (if the device sound is there, right click it and pick update driver now, but windows must be connected to the internet)
  17. Then click TAB, named DETAILS
  18. Last select, Properties, roller bar, and find Hardware ID's   (this is the super secret  chip IDENTIFICATION CODES)  ( see how to decode them here)
  19. Learn that 1 model laptop can be purchased day1 with 3 to 5 sound chips,  called OPTIONS , just like a new car  , 5 sound system choices, and only this step here tells you WHAT YOU HAVE, on desktops 100s of chips possible.
  20. Now we know that all sounds are dead, and the chip driver is bad, missing wrong or corrupted. (only 15 steps or 10 to find this truth) go to NODRIVER now.
  21. Lets say all PC system Sounds are ok, but the internet or music online or movies on line are soundless.  (that is a whole other matter.) covered next.
  22. Did you try all web browsers first,  IE8 to 11?  or Firefox V59 up? (did you know, many (and growing) XP IE brower is not banned?  Run Firefox v59+ for  free, it is never banned.
  23. Did you make sure you have a media player installed? for the web and for local music fails or local video,  try VLC here. Free and 100% Virus free too. (warning lots of other places offer this program loaded with malware or WORSE)

SHOW AND TELL:

Mixer, go to your task bar , click speaker ICON, and right click open mixer, make sure all bars are fully up, then click speaker icon on the left. and make sure its set to SPEAKERS. seen on the right below. This must be selected .
In the MIXER turn seen here fully up.  (not microphone) Right click task bar, speaker icon and pick sound mizer, bingo.

below is  Playback ( what you have here depends on how many devices your PC has,  only you know what you have and what you want as the sonic device heard.
Again Right click task bar, speaker but now pick playback devices, and enable what you are using,  speaker or headphones.

In the above example you pick #3 local sound. (this means the local chip decodes the sound, mixes it , amplifies it ( at weak 300mV levels) and sends it out the green 3.5mm sound line out jack.
Then the person using said JACK can use earbuds , head phones 3.5mm only or much better use real PC class, fully amplified, (has AC line power) SPEAKER sets and with a sub woofer for best effect.
That is how it works.
If  this fails to work on ear buds, at that jack the sound driver for the sound chip is wrong one, missing or corrupted. (to test this jack remove all usb sound devices, and all blue tooth sound devices, first)
If you have  Desktop PC we can have 2 sound chips, one on board, and the PCIe fancy  High end, sound card, that does say 7.1 Dolby sound
Connected up to my huge power amp and huge speakers. (no limits here but I first turn off the old chip in BIOS so the new card can work. (a Desktop here))


Photo 1: Control Panel W10 {CP}
CP


Photo2: Click SOUND TAB.   click Asterisk, then click TEST , if the green ARROW is not green that means windows thinks the DRIVER IS DEAD OR BAD.
If this test fails, then sound decoding is dead on this PC, this must work first, all other tests, for the 3.5mm jack are useless until local windows sounds start working, (first things first)
Push TEST, and listen.  There must be a wav file in the Sounds: Field box. if not windows is corrupted.
Windows will gray out TEST button if it thinks the sound card is dead (device= card=chip) leading us next to below... checks.
Some times windows thinks sound drivers are ok and are NOT OK at all.  Reload them is the JOB at hand next.


Photo 3: DM window or device manager.  Click Sound, ...  on the left first.
We are doing this to see if the sound driver is missing or failing, this is a sound chip driver, that was present the day you bought your PC new.
Try to now that PCs even one base model when sold new, may have had, many sound options sold new. 
Also know that your used old PC , may have had the sound card (Desktop) changed to upgrade, so don't expect your PC maker to know this nor have drivers supporting this unknown device.
In those cases we LOOK to find what is there, or scan it.
If a desktop and you see a PCIe Sound card in its slot,  you can read words stamped on the card easy to see what card it is, maker, and model, and we can match up drivers or it.

This is the Device manager below,  and there can be many clues here, about bad drivers,  if the driver is marked in red(yellow or Unknown) (mines Realtek but from HP on my laptop)
The key facts to know here and now are that there can be 4 states of conditions here.
  1. Missing, like if my Realtek line is missing there (click View tab, click show hidden devices)  This can happen missing if BIOS sound is turned off, so turn it on, see that here.
  2. Unknown on that line.
  3. Red maked, means its in ERROR CONDTION.
  4. Yellow marked means its in warning status.
In cases of 2,3,4 go to HP.com and load the correct driver, now. (or simply right click the device, and pick update driver)

Be aware that you might have 4 or more sound devices listed, (on board, USB sound, headphone sound, or even blue tooth, and more)  Below is my example of checking the Realtek on-board chip .
This screen below is Device manager ,selected from the Control Panel.  DM for short.
See my on-board Realtek sound chip Id's here.   See the Propery roller bar here,

NO DRIVER found?: See here how to find it, run PCI-z.exe program.  (called software Drivers) Only you PC maker has them, or Microsoft (mostly)
A chip can not work right or at all, if the driver
is missing, like a horse and the saddle is  missing you can't ride the horse , can you ?, but bare back rider "TONTO" can (pun)

SCANS are best:
Run PCI-z now, seen on my PCI scanning page, that covers how to discover and to get any driver made. (only if the above DM fails to work)
Be aware that Microsoft PnP Plug in Play fails on most chips made from 1989 to now.  (massive numbers of drivers used for years are not at Microsoft's update cache now(PnP)



Learn now that the PC you bought new, can and were sold with 5+ or more option sound cards or chips, just like you CAR was new with 10 more more SOUND SYSTEMS installed.

The PC has sub model codes in the say HP Service tag , with ABA# codes, this magic code tells any owner or HP pro what sound chip is there. (if not upgraded as many desktops are)
Guessing at the driver, will only make things worse, the above, ID tells any technician what chip is there, even it's version is there.
One can look inside a Desktop and see , ok no sound card upgrade there, then read the chip top next to the green 3.5mm jack , I can ! I can see the maker Realtek and the chip part number, clear as day. (and vast other names)
I can do a PCI-z scan to find it.
I can read the service tag.
I can go in to HP BIOS , click F1 information page and see the full ABA# there , as seen here.

The Blue-tooth chip (with its antenna) inside my PC Laptop, uses its own USB port #1 (this port is owned by BT) See block 26 here. (the sound chip is not used to make sounds, at all with BT, windows streams data to it using A2DP.
The USB head phones again do not use the sound chip, it sends data streams to the USB port and the head phones have there own sound chip inside there.
This page here, is about only the built sound card or chip.

End bad drivers.
Next is what I call Brats did this.
See here how they killed your sound.  Some Dweeb , pushed ESC key at power on, (HP) then F10 and then clicked System configuration and last turn off sound features. I hope the solution is obvious.


For funs and giggles I turned off all 3 above arrow marked devices.
Windows sounds go dead.
I booted to linux Ubuntu 16.04.2 ran the sound tests and it fails.
Linux could not load the sound driver with BIOS sounds turned off, showing that PnP fails in Linux too.
Here are some linux commands to scan hardware like this.




This Buds for you? (what's a bud?)  That is a standard industry 3.5mm (USA 1/8" ) JACK/PLUG.
Plug this in to green jack or one marked Line-out.(phones)
The desktop jack is green ,
on a silly laptop the jacks most times are only black and have only words there, but all desktops are green jacks. (only laptops buck that rule)
 (mic = microphone, spk = speaker ,on my HP no words at all, just icons engraved, as head phone icon and 1 microphone icon, so insert the phones in to the icon shown as phones)
Be advised some huge head phone (3.5mm) may sound weak, and this is normal, due to the weak output of the sound chip.
As a rule buds always work but huge phones that are very inefficient will be weak. (3.5mm jack , I and not talking about USB phones at all here)
We test with BUDs first, because they always work. (for this very weak signal)




SAY External speakers are dead ONLY  :
There are many kinds of speaker systems , (even USB, bluetooth , Wifi and even ethernet and more) But these 2 are what I will cover and are simple )
Passive and ACTIVE Speakers..
The first PASSIVE   are only seen on very custom systems, using  most times this DAC module as  starting point.
Passive speakers, (below is  neat speaker component, seen in the  casing (enclosure box) is missing below, is just voice coil inside, at 8 ohms (AC ohms not DC ohms) and the example below is wimpy speaker, 0.5 watts.
The word Passive mean with NO AMP , and Active means with AMP.  (the signals are very weak in any PC so need and AMP no matter what you do )
The Passive speakers have 2 naked wires, most times  black and one read are are polarized.  Red to Plus + is the rule.

Active speakers most commone have inside the enclosurean Audio Amplifier and is characterized by the fact that the connection to it  (sound) used, Phone jacks or Phono jacks, and there is a line power cord, either to AC power or to a wall wart power pack.
If you  see and AC or DC power jack or cord, it has and AMP and is ACTIVE speakers.

Passives speakers have no AMP and only have a naked, raw speaker inside of ANY SIZE, the below is a dinky do speaker (toy grade)
 
This is a real  Passive speaker they come in sizes 1" to over 18"inches,  and your PC sound chip can not operate this device, direct drive at all, it must have an AMP added.
That sound card or chip in your PC is not designed to power up and run any kind of RAW passive speaker.
The 3.5mm (1/8") phone jack as seen above in the Buds, has only 0.3v rms output max (99% of PCs, or 2v max if you have a professional grade added sound card like what ASUS sells. (PCI-e)

 The average home PC only does 10 milliwatts, (0.01 watts is weak) (about 0.3volts rms MAX)
Pro grade sound card can do 1.3v (rms) out. (4 times loader but dead weak still) and can drive 100-300 ohm PC 3.5mm head phones, but not 8ohm phones used on home stereo systems for over 50 years now.(hifi became stereo then)
The PRO Sound cards can hump out, 2v (rms) max.  a weak 1/2w (0.5) watts in to 8 ohms ,  and as you can see would drive the below speaker fully. But Most (99%) of sound cards (chips) overload in to 8 ohms, so.... fails.
The Sound card/chips output is always spec'd out as in to 600 ohm standard audio circuits (called LINE OUT) Some card are limted to 30ohm minimum loads or have special pro grade head phone jacks (I will not cover those)
If you use speaker or phones with 8 ohms voice coils inside (as seen below ) the sound is near impossible to hear. (needs and AMP it does) yes can be heard, ear placed close by,, but super weak output.
The speaker is called A WIRED speaker, or PASSIVE or even  sonic transducer (scientist named)
When inserted in to a speaker cabinet /box/ enclosure it is just  speaker, if the coil lugs seen below read infinity OHMS with a meter the coil inside is burned up.  (4 ohms ohms is common with  DMM meter)
 
This is an electro-magnetic acoustic speaker element device (this one is toy grade)  the lugs are the voice coil  + & -

To the average  consumer there are only 4 classes of speakers (besides quality and power)
  • USB
  • Passive  (like photo above)
  • ACtive. (powered amp speaker) Lets forget all I typed above, most folks never use Passive speakers ever, but is the best option, for many reason, (you can use standard pro grade amps and huge speakers)
  • Wireless (Bluetooth or WiFi)
Shopping for used speakers saves money and if you just gander at it , one can tell in a jiffy what is there.(or missing)
What you see is just black box or wood box with a grill.
What I see  inside and the wires and all jacks on the box.
If I see 2 very naked bare wires there , this is a PASSIVE speaker(s)  , just old speakers off and old 1980s hifi stereo or off most home theater systems.  (some are terrific sounding with a better AMP)
In most cases the label if marked 4 ohms or 8 or 16 ohms (8 is most common) that means it's PASSIVE . (inside can be crossover coils or the like)
IFthere is a USB jack then its a smart USB speaker set.
If the back has power jack it's abd ACTIVE speakers. (called in most cases A PC speaker set, and in most cases pretty poor sounding but with subwoofer sounds better)
If the back has RCA jacks , this can be either type class., I must look where the wires go, to and AMP or directly to the 2 lugs seen above on the speaker, called voice coil connectors.
If the jacks RCA say 4 or 8 or 16ohms this is a PASSIVE. (if no AC or DC jacks there, this is a PASSIVE SPEAKER, FOR SURE.
If the 2 wires go to a crossover network this too is PASSIVE and the cabinet has 2 or 3 speakers inside. (AND NO POWER CORDS)
Passive speakers may have naked wires, or 2 gold twist on lugs, or 2 spring operated lugs.
One way to get good speakers is to buy the naked cabinets or ones with dead speakers then go to mouser.com or any top seller of quality speakers and upgrade the box. (passive speaker upgrades)
This plate (naked) is marked 8 ohms so is Passive. You can find used huges speakers that sound super great and use and AMP to make any of them work perfectly.

Note the 8 ohms marked here, and 2 lugs bottom center, this is a passive speaker, no amp.

Old speakers, and funky screws , Passive. Zip cords are always ok.
This
speaker is ACTIVE see the line cord? Some have  DC jack and a wall wart, to AC, 12vcd or 12vac warts are common and are ACTIVE.

The above speaker clearly has RCA jacks there and are line inputs, that would work with my DAC.
In most cases all passive speakers are marked, ohm's.  And will fail connected to any line_out , phone jacks..
Tricks of the trade?
Convert  it to passive?, in all cases,   I can convert Active speakers to Passive, with 30 minutes work.
(just wires and soldering iron/pencil or station)
(I cut the wires to the speaker inside and wire up  a new speaker added jack or just run zip wire  from speaker to drilled hole in case rear.)
But why do that?, get some used PASSIVE speakers sold in thrift stores. Dirt cheap, make sure the cones are not damage, and most are GOOD to go.
Next would be the DAC and AMP below.


The correct choice for most folks is here. (called PC speakers)
REAL ACTIVE speakers with hidden inside , AMPLIFIER (AMP)
The other classes of Active speakers are USB speakers, that run totally off one USB cable. (not seen here)

Here are the real speakers, like these Labtec Pulse 325 below. (sub woofer class, and sound super good)
Rear view, see that 3.5mm plug (bingo) and the power pack plugs center rear, if missing power pack? the speakers will be dead.

If you plug the orange plug above into the  MIC jack (bam)  the speakers will be Dead use the Green SPK (phones/line out ) jack only.
The Speaker must have power and a amplifier or there will be no sounds. (sorry)

A custom sound setup: (one way to use PASSIVE speakers is to buy and start with this device)
THE DAC:
One can abandon his or here sound card and wire up a discrete sound system for there PC.  (we shut the sound down in Device manager , disable inside the PC)
You buy  USB DAC box . Seen next..

This is the PWM sound decoder, that has USB input and 2 or 3 RCA phone jacks out.

The USB plugs in to the REAR jack to PC, then the 2 , front RCA Jacks (L/R) are plugged into any Audio Amp you want, using industry standard RCA line cables. (this device below needs USB driver and DAC driver to work)
This device performs  Digital to Analog conversion, DAC it's called.
One advantage of the below device is it that it is not exposed to all that inside PC clocking noise, (huge) and also uses its own internal clock(quietly) that prevents sound jitter, windows is a really poor DAC, do to Windows can not run real time code on the DAC, Windows is a pre-preemptive multitasking OS, (unlike say DOS) Windows makes  very poor DAC.
The second advantage beside better ALAC music is you can now pick what sub components are best for you, the amp and the speakers (more choices) for quality of sound or upgrades at any time, from a better choice of speakers
I have real 1970s ALtec Lansing speaker, that I had to RE-CONE by my self ( a skill set learned in 1965) In My  opinion some of the best low cost speaker cabinets were made in the 70s. 
(re-cone them or new top end speakers elements added)
This is the DAC module.  (Folks that love better sounds buy and use this device, (or the link kind) connected to real audio sound systems, as seen below,  there is no ends to better sound.

Connect the above to the below via RCA cables. (sold at any Audio store or eBay) The sounds from this device are amazing. (buy one try it) I am not saying this is the best DAC, there are many some with built in Subwoofer jacks.
Then Connect the AMP outputs to real PASSIVE speakers.  (works with any passive speaker made from small to giant sized, note this AMP has Sub woofer driver out, too.)


The above takes the max of  0.3v RMS audio line outputs from a PC or from the DAC and increases (Amps up) the levels to 20v or 67 times increase (full  volume)
 The voltage out is 67 times more than the input.(max) due to the magic if a powerful Audio Amplifier inside.
Math for that is V = square root of  R X W  (R=8, W=50) 
You need 50watt speaker at the smallest size. 100watt be best. (IMO)
I run this old CLASS-A amp, from Kenwood, it has no custom chips, and can be repaired forever, but I never seen one fail, ever.
 (I have 2 of these amps one is garage amp for my DVD MP3 deck)    This thing can blow windows off there frames, or eardrums. The power spec on this is RMS power (means TRUE POWER and is not a lie)


Jargon used on Sound devices for decades. (and more)
First is the GREEN mini-phone JACK seen on all  DESKTOP PCs (Laptops will show earphones words or ICON or words line-out)
 Those are all 3.5mm (1/8") phone jacks, They are called PHONE because they shunk the old Ma Bell Telephone 1/4" phone jacks to this size in the 1960s or sooner. (aka as stereo mini phone jacks) GREEN is LINE OUT.

Some PCs have front rear and center out jacks. (I only cover 2 channel sound here Left and Right.) Mini Phone jacks these are called.

Next up and below, ares RCA PHONO jacks, used first by you guessed it RCA for there RCA turn tables (record player, decks for say your disk jockey)
The word PHONO means , PhonoGraph. (not phone as in TELEPHONE)  RCA made turn tables in the early days 1950 for  HiFI, with one jack mono out. Thus the name RCA.
The RCA jacks will be seen on real Amplifiers and on the DAC module on this page.
  these on the left plug in to those seen on the left. These are sold even with double shields for less noise.
These jacks are all LINE jacks, Line-IN, and Line-out, and means 600 ohm impedance and 300mV signals max.
All cables are COAX to prevent noise and for sure 60 Hz line hum noise found in every home.
Even better are double shielded coax cables, Zero hum pickup.
The 3.5mm PHONE plug , looks like this new below is a High Quality version, with Gold.
There are 3 paths here, tip, ring and sleeve(TRS) , the sleeve is always ground  the tip is left channel , center ring is right channel;
This is  also line out, on the green jack this 99% of the time sends 300mV (0.3v rms) to the speaker amps or to phone head or bugs. 
Head Phones,  to common types exist, 30 ohm and 300,  the latter work better as does sound card with 600 ohm source impedance or less. Many new sound cards have  powerful driver for phones, instead of the line-out usaged  so common.
By tradition in Audio impedance is  600 ohm, so voltages are rated to that load.
The 3.5mm best impedance is different, that is because it needs to power passive copper voice coil head phones, 32 to 300 ohms. (typ) 
In electronics, if you match impedances the maxiumum energy is transfered. (source Z = to load Z)Z is impedance, a mix of mostly resistance and inductance at audio frequencies.
 Equation :Impedance Z = R or XLor XC(if only one is present) then Z = √(R2 + X2) Xc , is not important at audio signal rates.(Hz)
When you see signals stated in dBm this means 600 ohm loads, for all audio work this was standardized by Ma Bell, in the early days of telephone, and the impedances  seen then  on 1 mile runs of telephone wires.
The Impedance is at a fixed frequency, A-weighted, or 1khz tone or 440Hz spec. because Z varies  from 20 Hz to 20k Hz.   (some just average it in the human hearing range)
Sound cards the Line out is anywhere from 100 ohms to 10,000,  300 is very common and works best with 300 ohm head sets. (100 to 600 is ideal)
Most cards are using a simple OP-AMP chip to drive this line. A famous 741 op_amp has 75ohm output impedance, so some makers use a 10k resistor in series and other uses 250  or 330 ohms total out. Read your spec on your card, of the 1000s made.
I see ASUS (tm) has  card that has a switch for <=32 ohms and over 32ohms. 
This only matters (ohms worry) with headphones never amps.
If you sound card has 1000 ohm source , and your phones are 32,  you will have weak sound (this is because 32 more times more signal stays in the card and not across the voice coils (ohms laws in a series circuit dictates this fact)
Lets say on high volume its 300mv out of the OP-AMP. instead of getting 1/2 that to the phones you get, 10mv on the voice coils.  E= I x R. It is .0003 amps .  You lose.
But on the other hand if both are 32 or close, they will be very load phones.  (a 150mV signal) (the exception is always possible if the phones are cheap very inefficient types)
What matters most are 2 things, the efficiency of the head phones, and sound quality.


OSD: Monitor Volume controls (On Screen Display) the Monitor has brain and you talk to it)
Some have front panel Volumn up and down, look for them
Cheaper or older monitors you must play inside the OSD as seen below,. Not only can be monitor AMP be tuned off muted, but the slider set to 0  ends all sounds, until you fix that.
Asus monitor.

ViewSonic

Not covered here and totally different solutions and hardware software are:
ALL USB HEAD PHONES. ( needs custom driver software to work and most are missing in the PNP Microsoft driver catalog SERVERS)
ALL USB SPEAKERS.  (did you try all USB ports first (try both the USB2 and 3 ports would be wise now) and test the DEVICE failing on another good PC? next)?
ALL BLUETOOTH speakers or head phones.
Wifi remote speakers ( soon to be in my home )
Even Ethernet wired speakers exist, now. 
Optical ports or  S/PDIF or TOSLink.
Each of these classes of sound devices  need there own software drivers to work. (if Microsoft Windows fails to find, them using its PnP plug and pray methods, then  ask the maker of these custom devices for there support software and load it now.
Learn that Microsoft even warns you they have no support for many devices in this list.
The most difficult can be USB headphones. (MS has huge stated warning about these on there support web site)
Microsoft  will  first tell (failures)  you to run the troubleshooter first. for sound.

Top causes of sound failures, is a wrong driver.
Caused by noob helper bee's that guess how to fix it and make it 2x worse.
They guess at what  sound chip is there or guess the PCs submodel (not looking  at service tags , is why) and then put on the wrong driver.
They also failed because the did not ask the PC's maker for help, but decided to guess and make it worse.  (if HP ask HP but first tell them the Service tag codes, 1,3,5)
They even guess the OS wrong,  they fail to see what OS they have then download the wrong driver, for the wrong OS. (endless here)
They go to hacker/scapler/malware sites (wow DON'T) and get a  driver, then infect the PC, and now you have 3 problems. (no sound, wrong driver, and now infected)
The last top cause to fail  is  you upgraded the OS, from say VISTA to Windows 7 then you discover there is no sound driver ever made for W7 for YOUR PC  and  its actual chip inside. sorry but those are facts.
(on a desktop this is easy fix get a new sound card or buy a USB sound dongle device,  that has sound chip inside and a 3.5mm  green jack for your external powered speakers or your headphones/earbuds.
Learn that many sound chip makers ended support at XP or VISTA for THAT CHIP. Super common is this issue today.  (no driver any where on mother earth for it  on say W7 up)
and more, noobs  kill more machines that anyone can count. (sound tops the list, then we see  wifi , then Ethernet dead)

Theories and practices and human logic:
To most folks sound is just some magic in the box,  and simple. (until it fails, same with your car dead)
Let me tell you it is not simple at all , if it fails, it can be hard to discover what is wrong. (thus my page)
To be clear if I could touch and see your PC, I can rattle through all this in 15minutes flat... (the logic of serial accurate disgnoses)
The 3 big first seen clues, Ah that PC, and That OS and omg THAT PCI sound card, (in 1 minute flat) add 3minuts side of PC desktop. or doing the scan in  seconds.
There are other types of failures,  I will not cover,  IE11 sound fails only., or one web site only fails, but windows sounds are ok,,  this is OUT OF MY SCOPE HERE.

version 1.  12-9-2017