Earbud and headphone listings are full of noise-related terms: ANC, ENC, hybrid ANC, transparency mode and more. They do different jobs, and confusing them is one of the most common reasons people end up disappointed with a pair. This explainer breaks down what each feature does, what the numbers on the box mean, and how to choose.
Quick answer
- ANC (active noise cancellation) reduces the noise you hear, such as traffic, fans and engine hum.
- ENC (environmental noise cancellation) reduces the noise the other person hears when you are on a call.
- Transparency or ambient mode deliberately lets outside sound in, so you can hear announcements or talk to someone without taking the earbuds out.
- Many budget earbuds advertise ENC but do not have ANC. Read the listing carefully.
What is ANC (active noise cancellation)?
ANC uses small microphones on the earbud or headphone to pick up outside sound. A chip then creates a matching “anti-noise” signal that is played through the speaker, cancelling part of the original sound before it reaches your ear.
ANC works best on steady, low-pitched sounds, such as an aircraft engine, a bus, an air conditioner or a ceiling fan. It is much less effective against sudden or high-pitched sounds, such as voices, honking or a baby crying. That’s why even very good ANC makes a flight quieter but doesn’t make a busy office silent.
Feedforward, feedback and hybrid ANC
- Feedforward ANC uses a microphone on the outside of the earbud to hear noise before it reaches you.
- Feedback ANC uses a microphone inside, near your ear, to measure what is actually getting through.
- Hybrid ANC combines both. It is generally more effective across a wider range of sounds, which is why it appears on most mid-range and premium models.
Adaptive ANC
Some products adjust the level of cancellation automatically based on your surroundings or the fit in your ear. This can make ANC feel more natural, though how well it works varies between brands.
What is ENC (environmental noise cancellation)?
ENC is about call quality. It uses one or more microphones and processing to separate your voice from background noise, so the person you are talking to hears you more clearly. It does nothing to reduce the noise you hear.
Brands sometimes advertise “quad-mic ENC” or “AI ENC”. More microphones can help, but real-world call quality depends heavily on tuning. Independent call recordings in reviews are the best way to judge it.
Passive noise isolation: the part that’s often forgotten
Before any electronics get involved, a good physical seal blocks a lot of sound, especially higher-pitched noise that ANC struggles with. For in-ear earbuds this means using the ear tip size that fits you properly. For over-ear headphones it means well-padded cups that sit fully around your ears.
If ANC feels weak, try a different ear tip size first. A poor seal can make even good ANC seem ineffective.
Transparency (ambient) mode
Transparency mode uses the outside microphones to pass sound through to your ears. It’s useful when you’re walking near traffic, listening for announcements at a station or airport, or having a quick conversation. Quality varies: the best versions sound natural, while weaker ones sound hissy or artificial.
What do “dB” claims on the box mean?
Brands often advertise ANC “up to 30dB”, “up to 45dB” or more. Treat these figures with caution:
- There is no single industry-wide test method for these claims, so numbers from different brands are not directly comparable.
- “Up to” usually refers to the best result at a particular frequency, not the average across all sounds.
- Fit makes a large difference, so your own result may differ.
Independent reviews that measure or carefully compare ANC are a more reliable guide than the number on the box.
Does ANC affect sound quality or battery life?
- Battery: ANC uses extra power, so battery life is usually shorter with it switched on. Most brands list figures for both ANC on and ANC off. Compare like with like.
- Sound: some listeners notice a slight change in sound or a faint hiss with ANC on, particularly on cheaper models.
- Comfort: a small number of people feel a sense of pressure with strong ANC. If that’s you, a model with adjustable ANC levels can help.
A note on Bluetooth codecs and LE Audio
Noise features are separate from audio codecs, but the two often appear together on spec sheets. Codecs decide how audio is compressed over Bluetooth. Common ones include SBC, AAC, LDAC and aptX. The best choice depends on your phone: iPhones use AAC, while support for LDAC and aptX varies between Android phones.
Newer devices are adding Bluetooth LE Audio, which uses the LC3 codec. The Bluetooth SIG says listening tests show LC3 delivering better quality than SBC even at half the bit rate, which can help battery life. LE Audio also adds Auracast, which lets one device broadcast audio to many listeners. Both your phone and your earbuds need to support LE Audio to use these features.
How to choose
- Daily commute by bus, metro or flight: prioritise hybrid ANC and a comfortable fit.
- Lots of calls from noisy places: look for strong ENC, and check call samples in reviews.
- Walking or cycling near traffic: make sure there’s a good transparency mode, and keep the volume sensible.
- Gym and workouts: a secure fit and water resistance (an IPX4 rating or higher) matter more than top-tier ANC.
- Tight budget: a well-fitting pair without ANC can still block a lot of noise passively. Avoid paying extra for ENC if you rarely take calls.
Safety tip
ANC can lower the volume you need to hear music clearly in noisy places, which is good for your hearing. But it also makes it harder to hear traffic, horns and announcements. Use transparency mode, or remove one earbud, when you need to stay aware of your surroundings.
Frequently asked questions
Is ENC the same as ANC?
No. ENC cleans up your voice for the person you are calling. ANC reduces the noise you hear. A product can have one without the other.
Can ANC block out voices completely?
No. ANC is most effective on steady, low-frequency sounds. Voices and sudden noises are reduced but not removed. A good ear tip seal helps.
Why does ANC sound weak on my earbuds?
The most common reason is a poor fit. Try other ear tip sizes, check for any fit test in the companion app, and make sure the earbuds’ firmware is up to date.
Do I need LE Audio?
Not yet for most people. It’s useful if both your phone and earbuds support it, and it will become more relevant as Auracast spreads to public venues and TVs.
Sources
- Bluetooth SIG: LE Audio, LC3 and Auracast (checked 16 October 2026)
