Advanced Audio Codec (AAC) is a digital audio compression standard that Bluetooth devices use to transmit music wirelessly. It reduces file size by removing audio data the human ear typically cannot detect, allowing devices to send good-quality sound over Bluetooth's limited bandwidth.
AAC improves on the older SBC (Subband Coding) codec that all Bluetooth devices must support by default. Where SBC often sounds thin or compressed, AAC delivers noticeably richer bass, clearer vocals, and more detailed highs at the same bitrate. Most modern wireless headphones, earbuds, and speakers use AAC as their primary codec.
Why it matters for buyers: Codec support directly affects sound quality. If your phone supports AAC and your headphones also support it, they will automatically pair using this codec instead of falling back to SBC. However, codec availability varies by device. iPhones favour AAC (since Apple created the standard), whilst Android phones increasingly support it but may default to other codecs like aptX or LDAC depending on the manufacturer.
Common misconception: Better codec does not always equal better sound. AAC at 256 kbps may sound worse than aptX at 150 kbps depending on implementation. Most people hear little difference in everyday listening, especially with decent headphones and a well-encoded source file.
What you should know: Check whether both your phone and headphones explicitly list AAC support before buying. On iPhones, AAC support is guaranteed. On Android, search the headphones' specifications or manual. Some budget phones may support only SBC, limiting your sound quality regardless of the headphones you choose. Codec support does not affect battery life significantly.