Bluetooth: This is what aptX, aptX HD and LDAC mean

If you like to move freely and want to listen to music, there is no getting around Bluetooth headphones. In this article you can read what the aptX, aptX HD and LDAC codecs are all about and how they change your wireless music enjoyment with Android 8.0.

Basics of wireless audio

• Bluetooth is a wireless form of transmission of data between mostly two devices over a short distance. This is done via radio waves (WPAN).
• The Danish king Harald Blauzahn (English: Harald Bluetooth) is the namesake of this technique because he reunited parts of Norway and Denmark.
• The Bluetooth symbol denotes the Nordic runes B and H.
• Three factors are essential for the transmission of music via bluetooth:
• The sampling rate (kHz): The higher the sampling rate, the cleaner the audio signals can be transmitted (analog to digital). Distortions in the sound decrease and the audible frequency range is expanded.
• The sampling depth (bit): The greater the sampling depth, the higher the music resolution. The dynamic increases as the area between soft and loud tones increases. In this way, much more fine sound levels and tonal nuances are possible.
• The transmission rate, also data transfer rate (kbps): This is colloquially the connection speed with which in this case the sound data of the music is transmitted from the device to the headphones. However, this is not entirely true.
• More specifically, it indicates the possible size of the amount of data that can be transmitted in a certain time. The higher the transfer rate for Bluetooth headphones, the more data (at the same time) can be transferred from the device. The audible sound improves significantly.

What does aptX, pptx HD and LDAC mean?

These abbreviations stand for Bluetooth codecs and basically describe differently powerful transmission options. They differ in the sampling rate, the sampling depth and the transmission rate. Android 8.0 comes with support for these audio codecs and you can enjoy better audio quality.

• With a sampling rate of 48 kHz and a sampling depth of 16 bits at a maximum transmission speed of 352 kilobits per second, atpX is the slowest option for wireless music enjoyment.
• The analog signal is read 48, 000 times per second and stored with 16 bits. Basically, these are solid numbers. For comparison, a CD is read and saved with identical data. However, the relatively slow transmission results in a 50% loss in sound quality. The sampling depth is therefore only 8 bits, which is at the expense of the music resolution.
• AtpX HD also has a sampling rate of 48 kHz, but the digital signal is saved with 24 bits. This increases the dynamic range, which leads to a finer sound. The use of LPCM (Linear Pulse Code Modulation) leads to lossless data transfer from the analog to a digital signal. This makes the sound more interference-free.
• PCM is a modulation process in which an analog signal is converted into a digital one. The analog sound waves of a music recording are put on the CD.
• The extent to which the transmission rate of this codec is adjusted in order to transmit the better sound to the headphones is not yet known.
• Sony's Bluetooth Codec LDAC is the best and fastest of the three ways of wireless audio. With a transmission rate of almost 1 Mbit / s at a sampling rate twice as high (96 kHz) and a sampling depth of 24 bits, almost CD quality is achieved.

Compatible Bluetooth headphones

• The current market offers both in-ear and over-ear headphones. These include, for example, the Sony h.ear in 2 WI-H700, the LG Tone Active + or the PSB M4U 8 headphones. For a full list of supporting wireless headphones, visit the aptX-HD website.
• The Sony MDR-1000X headphones and the MDR-1ABT support LDAC.

You can read our Bluetooth headphone comparison with the best and cheapest models here.