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TECH FEATURE

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A codec (short for compression/ decompression) is an algorithm that reduces the size of audio data for easier Bluetooth transmission from a source device to a listening device. The less compression, the better, and Bluetooth audio gear will often specify supported codecs. Here are some of the more common ones you’ll come across: • SBC (low complexity subband codec) is a universal digital audio encoder and decoder found in all Bluetooth devices. • ACC (Advanced Audio Coding) removes redundant signal elements to reduce the file size, while still maintaining high quality sound. It’s one of the most commonly supported Bluetooth codecs. Cracking the codecs • aptX delivers high sound quality by compressing and decompressing the Bluetooth audio between the source device and receiver; aptX HD reduces background noise for more authentic sound; aptX Low Latency

LUETOOTH BREAKING DOWN

Bluetooth transmission has revolutionised the way we connect and listen to music and other audio. But how does it improve the experience with each new version? Words Bec Summer T he standard for wireless transmission without the need for an internet connection, Bluetooth connects our significantly decreasing battery life. It was designed to enhance the communication range between multiple devices and/or mesh networks, and is commonly used in medical and fitness devices, and smart home automation.

decompresses the file as it’s playing to keep

audio in-sync for video and gaming; while Adaptive aptX provides seamless operation across multimedia.

devices simply and quickly, enabling audio streaming from a smartphone to portable speakers and ear gear. Why are there so many versions? Bluetooth has come a long way since its introduction in 1999, with each new version improving things like data transfer rates, security, range, and energy efficiency, as well as supporting new devices. Released in 2016, Bluetooth 5.0 increased transmission speed, decreased power consumption, and expanded the range to 200m outdoors and 40m indoors. The subsequent 5.1, 5.2 and 5.3 updates added location and signal detection, improved optimisation and latency, and algorithms to improve audio stream quality, respectively. The forthcoming 5.4 is expected to bring even lower power consumption, and support for bi-directional messages between a hub and multiple devices. What is Bluetooth LE? Bluetooth Low Energy allows devices to connect to Bluetooth for longer periods without

two devices simultaneously to one primary Bluetooth signal – look for devices supporting 5.0 and above. What’s the range? Bluetooth’s use in consumer tech has created the perception it only offers short-range transmission between devices, but the actual range can vary from less than a metre to more than a km; the lower the frequency, the greater the range. Bluetooth does have a shorter range than Wi-Fi, and factors that can affect signal strength include antenna gain and transmitter output, as well as physical obstacles made of metal, wood and glass. And Wi-Fi connection density in urban areas can sometimes overlap with Bluetooth signals. Coverage is generally better outdoors, while indoor Bluetooth has an average range of around 10m, so it’s always best to keep the audio device as close to your speakers and ear gear as possible.

Then there is Bluetooth LE Audio, which transmits high quality sound at low data rates. A single device can send multiple audio streams, so you can receive voice alerts while listening to music, and true wireless earbuds can individually connect to a phone, rather than one bud sending the signal to the other. LE Audio is not backwards compatible with the original ‘Classic’ Bluetooth Audio, however most new devices should support it. Does the Bluetooth version a device supports matter? The more compatible connected devices are, the better, but the good news is the Bluetooth signal protocol is backwards compatible, so you can connect a 5.2 speaker to a phone running 5.0 or lower. However, connected devices must support the same version to access any updates – eg. 5.2 headphones paired with a 5.0 phone will operate on 5.0 protocols. If you want to use multipoint – connecting

14 JULY 2023

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