Bluetooth Score and Tests

Headphones

Bluetooth versions vary from headphone to headphone and come with a suite of features that improve the data rate of transmission, battery life, or add additional codecs to reduce lag and latency. All Bluetooth standard versions support downward compatibility, which means that a smartphone running Bluetooth 5.0 will still work with headphones that are Bluetooth 4.2 and vice versa.

To test the Bluetooth version, we consult the headphone’s documentation to confirm the Bluetooth version, whether through product manuals, specification sheets, or simply checking the box. In the case that we can’t confirm the Bluetooth version with the information provided with the headphones, we consult the vendor page of the retailer we purchased the headphones from to see if there is additional information online. If we still can’t determine the official Bluetooth version, we make an educated guess based on the headphones’ release date, features, and device compatibility and specify in the review text that we couldn’t actually confirm the information.

It is worth noting that the Bluetooth version itself does not factor into the final Bluetooth score due to the potential difficulty in confirming the version information.

Multi-device pairing allows you to connect your Bluetooth headphones to multiple Bluetooth devices with full, simultaneous functionality on each source. Bluetooth headphones with multi-device pairing can connect to a Bluetooth-enabled laptop and smartphone at the same time and play media as well as take calls/use the microphone on both devices simultaneously. Some headphones support partial multi-device pairing, which means they can play and control audio on one Bluetooth device and use the microphone to make phone calls on another. We don't currently test for partial multi-device pairing, though, so it's not accounted for in our score.

To test multi-device pairing, we attempt to pair and connect the headphones to two separate Bluetooth devices (currently two Android phones). We then test both media playback and microphone control channels on each device to ensure all channels work simultaneously on both devices.

Note that the multi-device pairing test does not account for headphones that can mix audio from Bluetooth and another RF wireless source – it is exclusively for multi-device pairing via Bluetooth.

Most headphones use a typical “hold-to-pair” procedure that can get a little tedious, especially if you often switch between Bluetooth devices. Thankfully, some headphones use NFC is to quickly and efficiently transmit pairing protocols and connect and NFC-enabled device without too much hassle.

Like with Bluetooth Version, the NFC version is deducted via the paperwork that comes with the headphones. Usually, there is an NFC logo on the box, instruction manual, or even on the headphones themselves. If an indication of NFC compatibility is present, we attempt to pair the headphones with an NFC-enabled device to confirm proper functionality. If we cannot confirm whether the headphones support NFC or not, we indicate what we believe to best of our judgment and specify in the review text that the information could not be confirmed.

This is the headphones' range when in direct line of sight with the Bluetooth source. We test for this by connecting the headphones to the same Bluetooth 4.2 enabled phone or transmitter in a large open area such as a parking garage. We then evaluate the distance with the measuring wheel until the wireless connection is too weak to reliably transmit audio without any drops or issues in quality. This distance is also measured three times and then averaged to obtain the line of sight range.

Unless you are often in a large and open environment, line-of-sight range won't be as relevant for you and is therefore attributed a much lower percentage of the wireless score than obstructed range.

Base latency refers to the default sub-band coding that most wireless headphones use when connecting via Bluetooth. This typically occurs if the headphones do not have any additional codecs like aptX or AAC. It also happens when the codec is not supported by both Bluetooth devices. We also test the base latency of RF headphones with the same setup, but with the RF transmitter in place of the Bluetooth dongle.

We measure base latency using a Bluetooth 4.0 dongle that doesn’t have aptX or with the headphones’ dedicated RF transmitter. We connect the dongle/transmitter to our test sound card and record the test signal through the headphones, measuring the feedback delay. This is done three times and then averaged to give the final SBC latency number. Typical SBC latency ranges between 150 and 250 ms and RF between 20 and 75 ms.

AptX is a proprietary codec by Qualcomm (previously CSR) that improves audio quality and bit rate efficiency. This means headphones with aptX sound a bit better and less compressed when playing audio wirelessly. They also have a bit less latency than SBC although not as much as with the dedicated aptX (Low Latency) codec.

We measure aptX with a similar set up as that of the SBC sub-band coding latency. However, in this case, we use a Bluetooth 4.0 dongle with aptX support to measure the feedback delay. This test is also done three times and average to get the final aptX latency number. Typical aptX latency ranges between 50 to 150 ms.

AptX Low Latency (LL) is the fastest of the aptX codecs designed to reduce sync issues when watching videos or gaming. This codec usually performs much better than the standard aptX codec in terms of latency but does not improve sound quality.

Like the SBC and aptX latency test, a click track/input signal is sent to the headphones wirelessly, which is then recorded to determine the delay. For this test, we use a Bluetooth 4.1 dongle with aptX and aptX(LL) support. Again, we measure the latency with the DAW software three times to get the final aptX (LL) latency number. Typical aptX(LL) latency ranges between 30 and 50 ms.

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