Headphone connectivity determines how your headphones receive audio from a source device, and it shapes everything from sound quality to where you can listen. Today’s headphones use a mix of wireless Bluetooth connections and traditional wired cables, and a new generation of Bluetooth called LE Audio is adding features that change what headphones can do.
Bluetooth Classic and LE Audio
Bluetooth audio has traditionally operated on the Bluetooth Classic radio, which the Bluetooth Special Interest Group (SIG) refers to as Classic Audio. LE Audio, by contrast, runs on the Bluetooth Low Energy radio. According to the Bluetooth SIG, LE Audio not only supports the same audio products and use cases as Classic Audio but also introduces new features that improve performance and enable entirely new products and use cases.
This shift to the Low Energy radio opens up possibilities for lower power consumption while maintaining or even improving audio quality. Developers can use LE Audio to create headphones with longer battery life or smaller form factors, because the new architecture is more efficient than Classic Audio.
LE Audio features
LC3 codec
A central part of LE Audio is the Low Complexity Communications Codec, or LC3. The Bluetooth SIG states that LC3 provides high quality even at low data rates, giving developers flexibility to balance audio quality and power consumption. The organization notes that extensive listening checks have shown LC3 will provide improvements in audio quality over the SBC codec included with Classic Audio, even at a 50% lower bit rate. This efficiency means headphone makers can design products that either last longer on a charge or use a smaller battery without sacrificing sound.
Multi-Stream Audio
LE Audio also introduces Multi-Stream Audio, which the Bluetooth SIG describes as the ability to transmit multiple independent, synchronized audio streams between a source device like a smartphone and one or more audio sink devices. This feature can improve the performance of truly wireless earbuds. For example, it can deliver better stereo imaging, make voice assistant interactions more seamless, and allow smoother switching between multiple source devices.
Hearing aid support
Building on its low power, high quality, and multi-stream capabilities, LE Audio adds support for hearing aids. The Bluetooth SIG explains that Bluetooth audio has already brought significant benefits to a large portion of the global population, and LE Audio will enable the development of Bluetooth hearing aids that bring all the benefits of Bluetooth audio to the growing number of people with hearing loss. This integration is expected to make new phones and TVs equally accessible to users with hearing loss, according to the European Hearing Instrument Manufacturers Association, as cited by the Bluetooth SIG.
Auracast broadcast audio
One of the most talked-about LE Audio capabilities is Auracast broadcast audio. The Bluetooth SIG describes Auracast as a new Bluetooth capability that will let you share your audio, unmute your world, and hear your best. It enables an audio source device to broadcast one or more audio streams to an unlimited number of audio sink devices, such as headphones, earbuds, or hearing aids.
Auracast is designed to work in three main scenarios. First, it can let you invite others to share in your audio experience, bringing people closer together. Second, it can unmute televisions in public spaces, so you can fully enjoy the audio in places like gyms, airports, or waiting rooms. Third, it is expected to become the next generation of assistive listening technology, improving audio accessibility for people with hearing loss. The Bluetooth SIG notes that Auracast broadcast audio is well positioned to become an advanced assistive listening system that is easier to deploy than traditional systems such as inductive loops, while offering higher audio quality and greater privacy.
Joining an Auracast broadcast is designed to be simple. The Bluetooth SIG outlines three methods: searching for available broadcasts in a way similar to finding a Wi-Fi network, scanning a QR code, or tapping a device to an NFC tag. These options aim to make public audio accessible with minimal friction.
For a deeper look at wireless audio technologies, see our Bluetooth codecs guide.
Wired headphone connectivity
Wired headphones use a physical cable to carry an analog audio signal from a source device. The cable typically terminates in a plug such as a 3.5 mm mini-jack or a standard 6.3 mm plug.
One of the most important specifications for wired headphones is impedance, measured in ohms (Ω). According to beyerdynamic, impedance describes the electrical resistance of the voice coils in the headphone transducer. The company explains that the lighter the coil, the clearer and more precise the transducer can sound, but a lighter coil also means higher impedance. This means that not every source device can supply enough voltage to drive high-impedance headphones to a satisfying volume.
beyerdynamic categorizes headphone impedance into three broad ranges. Low impedance (16 to 32 Ω) works optimally with smartphones, laptops, and other mobile devices. Medium impedance (32 to 80 Ω) is well-suited for audio interfaces, creator setups, and home-studio environments. High impedance, starting from approximately 250 Ω, requires a powerful headphone amplifier and is often used in professional studios to deliver maximum fidelity. A 600 Ω model, such as the beyerdynamic DT 990 Edition, demands even more voltage and is intended for high-end headphone amplifiers.
To illustrate the effect of impedance on volume, beyerdynamic provides an example calculation. If you connect a pair of DT 770 PRO headphones (80 ohms) and a pair of DT 990 Edition headphones (600 ohms) to the same smartphone with an output voltage of 1 volt, the resulting power is very different. The 80-ohm headphones receive about 12.5 milliwatts, while the 600-ohm headphones receive only about 1.6 milliwatts. That means the lower-impedance model can supply almost eight times the power from the same source, leading to a noticeably higher volume. To achieve the same power with the high-impedance headphones, you would need to increase the voltage, which a dedicated headphone amplifier can do.
Matching impedance to your listening setup is therefore essential. If you mainly use a smartphone or tablet, low-impedance headphones will typically deliver a full, rich sound without extra equipment. For more on this topic, visit our impedance and sensitivity page.
Choosing the right connectivity for your needs
When evaluating headphone connectivity, it helps to think about where and how you plan to listen. Wireless Bluetooth headphones offer freedom of movement and are ideal for commuting, workouts, and everyday mobile use. LE Audio and Auracast add new sharing and accessibility features that may influence your choice if you often watch TV in public spaces or want to share audio with others. Wired headphones do not depend on Bluetooth codecs, but their impedance needs to suit your source device.
Check the specifications of any headphone you consider. For wireless models, look at the supported Bluetooth version and whether it includes LE Audio and Auracast. For wired models, note the impedance rating and compare it with the output capabilities of your source device. If your source cannot drive high-impedance headphones, a portable DAC/amplifier can bridge the gap. Always follow the manufacturer’s instructions for your specific model, as steps and compatibility can vary.
For a broader overview of headphone specifications, read our how to read headphone specs guide, and explore the full headphone specifications section for more details on battery life, microphones, and other features.
Frequently asked questions
What is the difference between Bluetooth Classic and LE Audio?
Bluetooth Classic Audio operates on the Bluetooth Classic radio, while LE Audio operates on the Bluetooth Low Energy radio. According to the Bluetooth SIG, LE Audio supports the same products and use cases as Classic Audio but adds new features such as the LC3 codec, Multi-Stream Audio, hearing aid support, and Auracast broadcast audio. LE Audio is designed to be more power-efficient, which can lead to longer battery life or smaller device designs.
Can I use high-impedance headphones with my smartphone?
You can physically connect high-impedance headphones to a smartphone, but they may sound very quiet. As beyerdynamic explains, high-impedance headphones need more voltage to reach a satisfying volume, and most smartphones do not supply enough power. A portable headphone amplifier or a DAC with a built-in amplifier can solve this problem by providing the necessary voltage.
How does Auracast broadcast audio work?
Auracast broadcast audio lets a source device, such as a TV or a smartphone, transmit one or more audio streams to an unlimited number of receiving devices like headphones, earbuds, or hearing aids. The Bluetooth SIG describes three ways to join a broadcast: searching for available Auracast streams similarly to Wi-Fi network selection, scanning a QR code, or tapping an NFC tag. This makes it possible to hear public TVs, assistive listening systems, or shared music without pairing each device individually.
For more information on headphone connectivity standards and specifications, visit our Connectivity category page.
