Start by naming the noise
People say 'my speakers are crackling' for at least four different problems. A scratchy crackle that appears when you touch the cable, a steady low hum that is there even with nothing playing, a soft hiss in quiet moments, and sharp pops or dropouts while the computer is busy all come from different places: contacts, grounding, the amplifier, and software respectively. Before you change anything, note what the noise sounds like and exactly when it happens. That one observation removes most of the guesswork.
Our speaker test helps with the first split. Play the left, both and right tones in turn and listen for whether the noise rides on one channel or both. Noise on one side only points to that speaker driver or that conductor in the cable. Identical noise on both sides points to something the two channels share: the source device, the amplifier or the power supply.
If you are testing on headphones, turn the volume down first. A pure tone concentrates all its energy at one frequency, so it sounds far louder than music at the same volume setting, and the upper part of a sweep is genuinely uncomfortable at high levels. Follow the low-volume warning on the page, start quiet, and raise the level only as far as you need to hear the fault.
Use the frequency sweep to separate a damaged driver from a signal problem
The sweep in our test rises from 20 Hz to 20 kHz over about eight seconds. Listen for where the noise shows up. If you hear rattling, buzzing or a torn, fuzzy edge only in one band, most often the bass, the likely causes are a damaged cone or voice coil, or a loose part that resonates at that frequency.
Resonance is not always inside the speaker. Grilles, screws, a monitor stand, or a pen lying on the desk will happily buzz along with a specific bass note. Repeat the sweep while pressing a hand on the cabinet and on nearby objects. If the rattle stops the moment you press on something, you have a mounting problem, not a broken speaker.
If instead the noise is present across the whole sweep, or it carries on after the tone stops, the driver is probably fine and the fault sits in the signal chain: cable, jack, amplifier, power or driver settings. The sections below narrow that down by noise type. One caution: small speakers cannot reproduce the very bottom of the sweep, and many adults cannot hear the top few kilohertz, so silence at the extremes is normal rather than a defect.
Crackle when the cable moves, and hum that never stops
Wiggle the plug gently or flex the cable while something is playing. If that produces crackling, you have a contact problem. The plating on 3.5 mm plugs and jacks wears over the years, and pocket lint builds up inside the socket. Blow the jack out with compressed air, wipe the plug with a dry cloth, then move the same cable to another device. If the crackle follows the cable, replace the cable; if it stays with the original device, the jack is worn. Crackling only while you turn a volume knob means the potentiometer behind that knob is dirty or worn.
A constant low hum or buzz with nothing playing is the classic sign of a ground loop. It is most common with a desktop PC feeding powered speakers that have their own mains plug: when the two are earthed at slightly different potentials, mains-frequency current finds its way along the audio cable shield. Plug the computer and the speakers into the same power strip first. If the hum remains, a ground-loop isolator placed in line on the audio cable resolves many cases.
If the noise changes when you move the mouse, scroll a page or load the graphics card, electrical interference inside the PC is leaking into the analogue output. Front-panel jacks are connected by a long internal lead and pick this up more readily, so try the rear motherboard jack. If it persists there too, an external USB DAC, which does the digital-to-analogue conversion outside the case, is the dependable fix.
Hiss at idle and how to set your volume controls
A faint hiss in silence is the amplifier's noise floor. Every amplifier has one. If the speaker's own volume knob is turned all the way up while the computer's volume sits near the bottom, you are sending a tiny signal and then amplifying it, along with the amplifier's self-noise, by a large amount. If you can only hear the hiss with your ear close to a powered speaker, that is within normal behaviour.
The fix is to reverse the gain staging. Set the computer or player volume high, somewhere around 80 to 100 percent, and bring the listening level down at the speaker or amplifier knob. A strong signal with little amplification gives noticeably less hiss at the same loudness. If the sound turns harsh when the source is at maximum, that stage is clipping, so back it off slightly until it cleans up.
Very sensitive in-ear monitors plugged straight into a PC jack exaggerate hiss for the same reason. That is the output stage's noise being revealed, not a fault in the earphones. Comparing them on a phone or another device will quickly tell you which end is responsible.
Pops and dropouts under load, and Bluetooth stutter
Pops, clicks or brief gaps that appear while a game loads, files copy or many browser tabs are open are audio buffer underruns. The audio device expects data at a steady pace. When another driver holds the CPU for too long, which is what high DPC latency means, the data arrives late and the gap is heard as a pop. Network, graphics and storage drivers are frequent culprits, so bringing those and the motherboard chipset drivers up to date is the standard first step.
For USB headsets and USB DACs, check power saving as well. Turning off USB selective suspend in the Windows power options and plugging directly into a port on the computer rather than a hub clears up many cases. If the audio device shares a hub with a webcam or an external drive, give it a port of its own.
Bluetooth stutter is usually a radio problem. The 2.4 GHz band is shared with Wi-Fi and wireless mouse receivers, and USB 3.0 ports and cables emit noise in the same range. Move a Bluetooth dongle away from USB 3.0 devices, or onto a short extension lead, and reduce the distance and obstacles between the devices. A sudden drop to thin, telephone-like sound the moment a microphone becomes active is the headset switching to its call profile; that is expected behaviour, not a defect.
Isolation steps, software fixes, and recognising a blown driver
Before blaming hardware, narrow the field with swaps. If the same speakers are noisy on a phone or another computer, the fault is in the speakers or cable; if they are clean elsewhere, it is the PC. Try a different cable, plug in headphones instead of the speakers, and switch between front and rear jacks. Those four checks usually show which section of the chain the problem lives in.
If it is the PC, open the device properties in the sound settings and look at the default format. A mismatch between the sample rate the application uses and the one the device is set to can produce crackling, so switching between 48 kHz and 44.1 kHz is worth a try. Next, turn off audio enhancements and spatial sound, and untick the option that lets applications take exclusive control of the device, which rules out conflicts when one program grabs the hardware. If the noise began right after an update, roll the audio driver back; if the driver is years old, install the manufacturer's current version.
Finally, the signs of a physically blown driver: distortion on bass notes even at low volume, the same fault on every source you try, and a rattle that always lands at the same point in the sweep. That indicates a torn cone or a rubbing voice coil. No setting will repair it, and playing it loud makes it worse, so check your warranty and arrange a replacement or repair. If your problem is one side being completely silent rather than noisy, our guide on one-sided sound walks through that diagnosis.