Headphones & Audio
Two of the most confusing lines on a wireless earbud spec sheet are the audio codec and the battery rating. Understanding both helps you read manufacturer claims without over-reading them.
A Bluetooth audio codec is the method used to compress and transmit sound wirelessly. For years the universal baseline has been SBC. Newer options aim to improve efficiency or quality: as part of Bluetooth LE Audio, the Bluetooth Special Interest Group (the standards body that governs Bluetooth) introduced LC3, the Low Complexity Communication Codec, which it adopted in 2020 with Bluetooth 5.2. LC3 is designed to deliver good audio quality at lower bitrates than SBC. Vendors also promote their own or licensed codecs (for example higher-bitrate options aimed at hi-res streaming), but a codec only works if both the earbuds and the source device support it — so a codec listed on the earbuds is not usable unless your phone supports it too. That is why we verify codec support against the manufacturer's official spec sheet and, when a launch document doesn't state a specific codec, we don't assume it.
Battery ratings deserve similar care. A manufacturer's "up to X hours" is a rated figure measured under the company's own conditions — typically a specific volume level, and often with features like spatial/immersive audio or active noise cancellation turned off or on in ways the fine print specifies. This is why the same earbuds can be rated, say, up to 6 hours normally but only up to 4 hours with an immersive-audio mode enabled. Two numbers usually appear: per-earbud playback on a single charge, and total playback including the charging case's extra charges. When comparing products, compare like with like (ANC-on to ANC-on) and treat every figure as manufacturer-rated rather than a measured outcome.
Firsthand does not run an audio lab, so we report these figures exactly as the manufacturer rates them and cite the official source. The practical takeaway: check that a codec is supported on both ends, read whether a battery rating is with ANC or immersive audio on or off, and separate per-earbud from with-case totals. This article is educational and cites the Bluetooth SIG and manufacturer documentation; it is not a measurement.