Bluetooth codecs: For reasons I cite in my blog about Bluetooth audio codecs, we didn’t mandate the inclusion of any specific audio codec-the technology that reduces the amount of data in a digital audio file so it can stream reliably over a Bluetooth connection.

For more information on Wi-Fi–based speakers, see our guides to the best multiroom wireless speaker system, the best Alexa speaker, and the best Google Home speaker. They do not include any Wi-Fi–based technology like Sonos, Alexa, or Chromecast. Wireless connectivity: Speakers tested for this guide are Bluetooth-only.

The phone is not transmitting anything by radio, so it must be induction. Put your iPhone in Airplane mode & test it on the speaker. The magnetic field generated by the speaker coil is very low, but is just strong enough that if you put a 'receiver' consisting of another coil & magnet, you can generate just enough current to power a small amplifier, which can then re-transmit that to a new speaker as amplified sound. If you attach that magnet to a paper or plastic cone - you have a speaker.Ĭonversely, if you vibrate that cone, you induce a current in the wire coil - & there you have a microphone. If you pass an alternating current through a wire wrapped round a magnet, the current will induce a magnetic field, causing the magnet to move.

They actually 'listen' to the magnetic field in the phone's speaker itself. On re-reading, this may not be the actual answer… if it's bluetooth, then it's bluetooth - but if it works in Airplane mode, then read on.

Wifi vs bluetooth speaker