What does low latency mean on headphones?

Chapter 1: What is the role of latency in wireless headphones?

Latency plays an important role in determining the efficiency of wireless headphones. Technically in terms of Bluetooth audio, it is the length of time between the signal transmission and sound output generated by the headphone speakers.

The slight delay thus generated is a result of several processes in the system that take time to complete before the desired sound output is generated.

The concept of latency tolerance varies from person to person as normal people can’t perceive a difference in latency below 20ms, and many can’t judge a difference between 40 to 80ms.

However, above 150ms the difference becomes noticeable, hence, Bluetooth headphones should offer at least a latency of less than 100 ms to deliver a commendable sound performance.

In context to wireless headphones, low latency allows the user to react to the sound more quickly, increasing their response rate and in-game success.

Chapter 2: How to minimize Audio Latency?

Bluetooth devices use a wide array of digital audio encoders and decoders, also known as codecs that are used to transfer data from the audio source to a Bluetooth receiver in the headphones.

The codecs provide different types of advantages and disadvantages at the time that are unique to each. Some codecs are developed to resolve latency issues, while some are used to increase the gain of the signal.

Most Bluetooth headphones in the market support the SBC (Sub Band Codec), which has a minimum delay of 200 to 220ms. Here are some additional codecs found in the most popular Bluetooth headphones:

• LDAC: It is Sony’s proprietary Bluetooth audio codec with variable bit rate support.
• aptX: It offers 48kHz/16-bit audio, better sound quality than the SBC codec. The latency is between 100 to 170ms.
• aptX HD: It’s an improvement over the aptX codec, offering 48kHz/24-bit audio.
• aptX Low Latency: It is an innovative code offering just 30 to 40ms latency, ideal for gaming and videos.
• FastStream: It offers two-way support for SBC audio with a latency of less than 40ms. Although, it’s not commonly found in consumer Bluetooth devices.

For the above-mentioned codecs to work, both the transmitter and the receiving device must support the same audio codec.

For gaming and watching videos, both aptX low Latency and FastStream are ideal choices for users who want an immersive audio experience.

Chapter 3: How good is aptX Low Latency?

Qualcomm, the semiconductor giant acquired the rights of the original aptX codec to create an efficient codec that can address the high latency (more than 100ms) issue on home entertainment devices.

While watching a movie, if the audio track has a latency of more than 100ms, it will go behind the streaming video, disrupting the viewing experience. Similarly in gaming, an audio latency of more than 100ms can mean poor in-game performance.

Qualcomm has developed two versions of the original aptX codec: aptX HD and aptX Low Latency. While the aptX HD is designed for delivering high-quality sound, the aptX Low Latency codec is a dedicated solution for gamers.

The important factor to note here is that iPhones or any iOS device won’t support the aptX codec as Apple uses its W1 codec to achieve low latency audio over Bluetooth devices. So buying aptX codec earphones for iOS devices won’t make any difference to the sound output.

Chapter 4: How to determine the latency of any headphones?

There’s no sure-shot way of determining the latency of the Bluetooth headphones. However, two main ways can help us to estimate the latency of particular headphones.

1. Codec Version

By knowing the codec version supported by any headphones, you can easily know the capabilities of the headphones and predict the latency range of the model. The information related to the Codec Support is mainly found in the operation manual supplied with the headphone device.

If there is no manual, you can check the information at the official website of the headphones or from the product description found on the e-commerce websites.

2. Bluetooth Version

The secondary step is to identify the Bluetooth version supported by the specific model. As Bluetooth versions vary greatly, it’s important to know the version to understand the codecs supported by a certain model. Based on the codec supported by the headphones, you can classify the latency accordingly.

It is important to note that all Bluetooth standard versions have downward compatibility, which means a smartphone with support for Bluetooth 5.0 will also work with headphones on a lower Bluetooth version, and vice versa.

To check the Bluetooth version of any headphones, you can check the documentation, product manuals, specification sheets, or the box of the product.

Chapter 5: How to fix audio latency?

While there is no single way to eliminate audio latency, there are many practices that can help reduce the audio latency to ensure a pleasurable listening experience.

1. Selecting the right audio codec

The primary step to fix audio latency is to understand the efficiency of codecs. For all platforms (Android, Windows, Mac, and iOS), the compatibility and performance of codecs may vary. This implies that you need to select the right pair of Bluetooth headphones that can match the platform you’re using as an audio source.

For instance, there are codecs like aptX HD and aptX LL that provide top-notch audio performance. However, these devices won’t work on a MAC or an iPhone. So make sure you only select aptX codec headphones when you’re using an Android smartphone or a Windows PC.

2. Selecting the right audio profile  

The bandwidth of Bluetooth transmission varies with the version of Bluetooth supported by the devices (audio source and headphones). If you have a device that works on Bluetooth 4.1 and headphones that work on Bluetooth 5.0, the connection will only utilize the Bluetooth 4.1 standard.

Therefore, it is essential to choose the latest version to take advantage of the improved bandwidth and features in the newer versions.

In the majority of the cases, selecting the right codec and audio profile reduces the sound delay considerably and delivers a good listening experience.