Wireless audio reviews tend to rank products by audio quality, which is the hardest attribute to compare and often the least decisive. The attributes that decide whether a pair of headphones is lived with or abandoned are more prosaic: whether the codec chain works with the specific phone in question, whether the seal fits an individual ear, whether noise cancelling handles the noise the owner actually encounters, and whether the battery still holds a working day after two years.
Codecs: what is supported, and what is audible
Every Bluetooth audio device supports SBC, the baseline codec, and most support AAC. Above that the ladder is proprietary: aptX and its variants, LDAC, and LHDC, with LC3 arriving alongside newer Bluetooth audio profiles. The decisive fact is not which codec is best in the abstract but which codec both ends of the link can use. An iPhone transmits AAC and does not transmit aptX or LDAC, so headphones whose quality depends on LDAC will run in AAC there; several Android vendors support LDAC or LHDC but not aptX, and the reverse also occurs. Checking the pairing of phone and headphone is more useful than comparing codec bitrates.
Within that constraint, the audible differences are smaller than the numbers suggest. Above roughly 256 kbps, differences between competent implementations are subtle and heavily dependent on the master recording, while the transducer - the driver and its housing - dominates what is actually heard. A well-tuned pair on SBC will comfortably outperform a poor pair on LDAC.
Latency
Bluetooth audio introduces delay between the video frame and the sound. SBC typically adds around 150 to 250 milliseconds, and codecs designed for low latency, including aptX Low Latency and the gaming modes built into many chipsets, reduce this to roughly 40 to 80 milliseconds. Streaming apps hide the problem by delaying the video to match, and most phones do the same for video playback. The cases that expose it are gaming, live monitoring and any situation where the source does not compensate. Where those uses matter, the specification to look for is not a codec name but a stated end-to-end latency figure.
Noise cancelling: three designs, one limitation
Active noise cancelling works by sampling ambient sound with microphones and playing an inverted copy of it. Feedforward designs place microphones on the outside of the housing and are good at steady low-frequency noise. Feedback designs place them inside the ear cup, closer to the listener, and handle a narrower band but with better accuracy. Hybrid designs use both and are what almost every current premium product implements. Insertion loss, the reduction measured in decibels, is typically 20 to 30 dB in the low-frequency band where it works best.
The limitation is inherent. Active cancelling is effective against continuous, low-frequency sound - engine drone, air-conditioning, aircraft cabin noise - and largely ineffective against speech, because speech is broadband, non-continuous and arrives from unpredictable directions. The passive seal is what handles voices, and that is a mechanical property of the ear cup and its fit, not an electronic one.
Transparency mode and volume limits
Transparency, or pass-through, mode mixes ambient sound back in through the microphones. It is useful for conversation and for awareness while walking, and its quality varies widely: poorly implemented transparency sounds artificially amplified and hollow. Many models also enforce a volume limit in transparency mode, which is a safety feature rather than a defect. Related to it are the hearing-protection systems that cap output or attenuate sudden loud transients, and their behaviour differs enough between models that it is worth reading rather than assuming.
Battery: the specification that ages
Battery life is published with noise cancelling on, off, and at a stated volume, and the gap between the figures can be half the runtime. The more consequential number is the ageing curve. A sealed lithium cell in a small housing loses capacity faster than one with thermal headroom, and a pair rated at 30 hours new may deliver 18 to 22 hours after two or three years of daily use. Where a cell is replaceable, that is a genuine long-term advantage; where it is not, the battery effectively sets the service life of the product.
Multipoint and connection management
Multipoint lets one pair hold connections to two sources at once and switch between them, which matters for anyone moving between a laptop and a phone during the day. The quality of the implementation varies more than the feature list implies: some switch cleanly on the first audio event, others require manual intervention, and a few handle three devices well while others manage two badly. For a single-source owner the feature is irrelevant; for a two-source owner it is close to essential.
Fit and seal outweigh everything else
Headphone measurements are taken on a standardised rig with a defined seal, and an individual ear is not that rig. A few millimetres of difference in insertion depth changes the low-frequency response more than any codec or amplifier choice, and it changes noise cancelling performance just as much, because passive attenuation is part of the total. This is why identical headphones receive opposite assessments from different listeners, and why ear-tip sizing and replacement are worth more attention than they usually receive.
Wired fallback
A wired connection removes the codec, the latency and the battery from the equation, and it remains the reference against which wireless performance should be judged. Whether a model supports passive wired operation - that is, playing with the power off - is worth checking, since it decides whether the headphones can be used on a long flight after the battery is exhausted. Models that require power for wired operation are effectively tethering the listener to a charging schedule.