Bluetooth Codecs Explained: AAC, aptX and LDAC

By Suraj Giri, reviewed by Suraj Giri on September 26, 2026
Published September 26, 2026. 5 min read.

A Bluetooth codec is the method your phone uses to compress audio before sending it to your earbuds, and your earbuds use the same codec to decode it. Both devices must support a codec for it to be used. Sony's help guide calls a codec an "audio coding algorithm" used when sound travels over Bluetooth. It's one of several listening settings on your earbuds, next to features like noise cancelling, which is covered in how noise cancelling works on earbuds.

If your headphones sound muffled or quiet, check the simpler causes before the codec: a blocked speaker mesh, the fit, or a volume setting. Our guide for headphones volume too low goes through them in order. Every codec fact below comes from Sony, Qualcomm, the Bluetooth SIG, Google or Apple, read on September 26, 2026.

Over-ear headphones and an open black earbuds case on a walnut desk with acoustic panels behind — A listening corner with headphones and earbuds side by side. Illustration: Gadget247News, generated with Runway

How Do Bluetooth Codecs Work?

Bluetooth codecs work in pairs: the phone encodes the music with one codec, sends it over Bluetooth, and the earbuds decode it with the same one. Sony's WH-1000XM6 guide says the headset "switches to that codec automatically" when music arrives in a codec it supports. The phone makes the choice. Sony notes that if a phone supports a codec of higher sound quality than SBC, "you may need to set the device beforehand" to use it. Qualcomm adds a hardware rule for aptX: both the sending device and the headphones "must have aptX support built into their Bluetooth audio chipset."

SBC vs AAC vs aptX vs LDAC vs LC3

The table compares the five codecs this page covers, using only what each official source states.

Codec	Developed by	Needs support on	What the official source says	Source
SBC (Subband Codec)	Part of the Bluetooth standard	Any Bluetooth audio device	"All Bluetooth devices support SBC"; included with Classic Audio	Sony, Bluetooth SIG
AAC (Advanced Audio Coding)	Not named on the pages we read	Phone and earbuds	Can provide higher sound quality than SBC; "mainly used in Apple products such as iPhone"	Sony
aptX family	Qualcomm	Phone and headphones, in the Bluetooth chip	aptX Adaptive: "Typically, 279kbps to 420kbps"; backwards compatible with aptX and aptX HD	Qualcomm
LDAC	Sony	Phone and headphones	Carries Hi-Res Audio over Bluetooth; about 3 times more data than SBC at two specific bitrates	Sony
LC3 (Low Complexity Communications Codec)	Part of LE Audio	LE Audio phone and LE Audio earbuds	Better audio quality than SBC "even at a 50% lower bit rate"	Bluetooth SIG

No codec wins on its own: the one you hear depends on what your phone and your earbuds both support.

What Is LDAC?

LDAC is Sony's codec for High-Resolution (Hi-Res) Audio over Bluetooth. Sony says it works "without any down-conversion" of Hi-Res content, except DSD files. Its figure of about 3 times more data than SBC applies only when one of two specific bitrates is selected. Sony's LDAC page says the source code was contributed to the Android Open Source Project so smartphone makers can install it, and Android's developer settings list LDAC as a codec choice.

What Is aptX?

aptX is Qualcomm's family of Bluetooth codecs. Qualcomm's aptX site lists aptX Adaptive, aptX HD, aptX Low Latency and aptX. aptX Adaptive "dynamically adjusts bit rate to connection quality." aptX Lossless is "exclusively available as part of Snapdragon Sound" and, in Qualcomm's words, "transmits up to 24bit/96 kHz audio over Bluetooth." Both the phone and the headphones need aptX support in their Bluetooth audio chipset.

Which Codec Will My Earbuds Use?

Your earbuds use a codec that both they and your phone support, and the phone's choice decides which one. Sony's WH-1000XM6 shows how this plays out. Over a Classic Audio connection it plays SBC, AAC or LDAC. Over an LE Audio connection it plays LC3, and for that Sony says to set the sound quality mode to Low latency in the Sony | Sound Connect app. In Prioritize Sound Quality, the factory setting, "LE Audio connection is not available."

Does iPhone Support aptX or LDAC?

Apple doesn't list aptX or LDAC for iPhone on the support pages we read on September 26, 2026. Apple says AirPods 3 or earlier, AirPods Pro 1, AirPods Pro 2 with Lightning Charging Case, AirPods Max and "most Beats wireless headphones use Apple AAC Bluetooth Codec", and adds that "Bluetooth connections aren't lossless." Sony's guide describes AAC as the codec "mainly used in Apple products such as iPhone."

How to Check or Change the Codec

Android phones can change the codec from a settings screen called Developer options, which you have to turn on first. Google's steps for a Pixel:

Go to Settings → About phone and tap Build number seven times to turn on Developer options.
Return to the previous screen to find Developer options at the bottom.
Open Developer options, tap Bluetooth Audio Codec and pick a codec that your earbuds also support.

Google notes that on some devices this screen "might be located or named differently," so check your phone maker's help if you can't find it. Sony's WH-1000XM6 adds its own control: the Sound Connect app's sound quality mode, which offers Prioritize Sound Quality, Prioritize Stable Connection and Low latency.

Four numbered steps to change the Bluetooth codec on a Pixel phone: tap Build number seven times in About phone, return to find Developer options, tap Bluetooth Audio Codec, then pick a codec your earbuds also support. — Changing the Bluetooth codec on a Pixel phone, from Google's Android developer options page. Diagram: Gadget247News

Codec Problems

Two codec side effects are worth knowing before you troubleshoot: a trade-off between sound quality and a stable connection, and a codec limit when multipoint is on.

Can a Codec Cause Muffled Sound or Dropouts?

On Sony's WH-1000XM6, the sound quality mode can play a part in dropouts, and Sony's fix is to switch modes. For intermittent sound, Sony says to "select [Prioritize Stable Connection]" in the Sound Connect app. It also notes that Low latency mode, which it describes as an LE Audio connection, has "a lower connection stability" than the other two. Multipoint can also limit codecs: on Sony's WH-1000XM4, LDAC can't be used while Connect to 2 devices simultaneously is on, as explained in What Is Bluetooth Multipoint and Which Earbuds Support It. Muffled sound is a different problem. Start with the mesh, fit and volume checks in the guide linked at the top.

Hearing Features Are Different From Codecs

A codec changes how audio travels from your phone to your earbuds. A hearing feature changes the sound itself: Apple's Hearing Aid feature on AirPods Pro 2 and AirPods Pro 3 uses a hearing test result "to customize the sound of your AirPods for your specific hearing needs." The setup is in How to Use AirPods as a Hearing Aid. LE Audio, the standard that brings LC3, also "adds support for hearing aids," according to the Bluetooth SIG.

Codecs: Quick Answers

Is LDAC better than aptX?

LDAC and aptX only work when both of your devices support the same one, so the practical choice is the codec your phone and earbuds share. Sony describes LDAC as sending about 3 times more data than SBC at two specific bitrates, while Qualcomm gives aptX Adaptive as typically 279 to 420 kbps. Those two figures measure different things, so they don't rank one codec above the other.

Does LE Audio replace aptX and LDAC?

Not on the headphones Sony documents: the WH-1000XM6 keeps SBC, AAC and LDAC for Classic Audio and adds LC3 for LE Audio. The Bluetooth SIG says Classic Audio runs on the Bluetooth Classic radio and LE Audio on the Bluetooth Low Energy radio. LE Audio also adds broadcast audio, covered in Auracast broadcast audio on headphones.