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IoT Blog

Improvements in Bluetooth Audio Quality Could Benefit All Your IoT Devices

Bluetooth technology is one of the most convenient ways to sync audio to IoT devices, however, in the past, the audio quality hasn’t always been up to par. Early Bluetooth connections had latency issues, poor noise reduction and low quality audio playback. 

But with newer Bluetooth products on the market, we’re seeing vast improvements in these areas, which could make this technology the go-to choice for IoT device manufacturers and audiophiles. With clearer voice recognition, extended antennas, reduced latency and less aggressive compression, Bluetooth audio quality is better than ever. It’s worthy of serious consideration for all your IoT devices.

Streamlined Voice Control and Recognition 
Today’s most advanced IoT devices use voice recognition to control key features—in fact, more than 50 percent of households in the United States use voice recognition to control at least one of their devices. With Bluetooth’s ability to pair seamlessly with a wide range of devices, from phones to personal assistants, it’s becoming the number one syncing choice for manufacturers too. Improvements in Bluetooth audio quality have refined the process even further. Past versions of Bluetooth used a Continuously Variable Slope Delta (CVSD) voice codec to recognize speech patterns. Since this frequency was limited to just 4 kHz, voice recognition wasn’t always accurate. And, at times, the device couldn’t understand the original trigger phrase, resulting in errors. 

The Bluetooth hands-free profile now has the option to include a voice codec based on mobile Sub-Band Coding (mSBC) technology instead of CVSD. This version features an expanded frequency of 8 kHz, meaning that trigger phrases sound clearer, and the result is far fewer comprehension problems. 

Yet the real benefit of improved Bluetooth audio quality for voice recognition arises when mSBC is coupled with better cellular network connections. Many cellular networks still use Adaptive Multi-Rate (AMR) speech encoding, which only optimizes audio between 300 Hz and 3.4 kHz. The newer version—AMR Wideband (sometimes called HD Voice)—extends this optimization even further, between 50 Hz and 7 kHz. When you combine the Bluetooth mSBC encoder with an HD Voice cellular network, the result is more natural-sounding voice inputs. This, in turn, improves voice recognition accuracy. 

Extending Your Reach to More IoT Devices 
External antennas also improve the Bluetooth connection quality at greater distances. On average, Bluetooth devices without external antennas and amplifiers have a reach of about 20 meters, give or take 5 meters depending upon the device and the environment (such as walls or other obstacles that might interfere with the connection). With this technology, the signal quality deteriorates rapidly as the user and their Bluetooth device get further and further away.

Today’s Bluetooth manufacturers are using external amplifiers and antennas with Bluetooth to avoid broken connections. Using an external antenna, you could expand the coverage area of any Bluetooth device to as much as 500 meters, on average. That’s about 25 times as much distance as you currently get with an internal antennas. 

Improved Bluetooth Audio Quality for Music  
One of the biggest issues that music fans encounter when using Bluetooth connections surrounds compression. Audio files need to be compressed in order for the Bluetooth device to send and receive the data. Bluetooth’s low data rates result in longer battery life for your device, but high-quality audio often pays a high price for this convenience. 

All Bluetooth technology compresses files to a certain extent, but the amount of compression depends upon the audio codec that’s being used. Most versions of Bluetooth use the standard Subband Codec (SBC) to compress files. This type of compression is very aggressive, especially at higher frequencies. You can often hear a major loss of quality in devices using this codec. 

Bluetooth audio quality has improved, in part, because more smart devices are using less aggressive compression codecs, including Qualcomm’s aptX and aptX-HD. These codecs still compress audio files, but the loss in quality is far less noticeable. Newer Bluetooth devices can support multiple codecs ranging from SBC to aptX-HD, which means that you’ll get the best quality audio available based upon your smart device. Both the device and the Bluetooth connection must use the same codec to communicate, and the smart device itself dictates which codec to use. With Bluetooth’s flexible support for a range of compression algorithms, you’ll always get the highest quality sound possible based on the devices you own. 

Barely Noticeable Latency 
With its ability to pair seamlessly with a range of devices, Bluetooth is the most convenient method for syncing audio to video inputs, however, in practice, latency can make this connection virtually unusable. Most Bluetooth connections have a default latency of 200 ms, and this can increase by as much as 100 ms if anything obstructs the connection. For most video and gaming needs, this is far too slow—most people will notice lag around the 200 ms mark. 

With new codecs from Qualcomm, including aptX and aptX-LL, Bluetooth audio quality and latency has greatly improved. With an aptX transmitter, the latency is now down to 150 ms, with a less than 20 ms variability. The aptX-LL transmitter improves latency even further, bringing it down to just 40 ms, with a 10 ms variability. With this latency, you might notice a very, very small lag between the audio and the video if you look carefully, but the two will sync up almost instantaneously.  

Wireless Stereo
New technology from Bluetooth device providers is also making it possible to implement a true stereo system using only Bluetooth connections. This setup can be complex, especially if you want to use a smart device—like your phone—to separate the audio stream into two channels. 

Bluetooth audio quality and latency has improved enough to allow your device to connect to both a left and right speaker without the added complexity of physical wires. Your audio can simply stream to the first Bluetooth module in one speaker, which creates its connection to the second Bluetooth module inside of the other speaker. What makes this a great option for use over wired connections is that the second module never has to interact with the phone, thereby streamlining the process significantly. 

Sierra Wireless creates modules with the latest advances in Bluetooth connectivity in mind, including our AirPrime® BC127. This and other modules are designed to connect your audio without significant quality loss. You enjoy all this with a reduced time-to-market due to simplified integration features. Start with Sierra today to find out how you can incorporate the best Bluetooth audio quality into your IoT devices.