If you use wireless headphones, you are probably using a Bluetooth connection. Bluetooth lets you enjoy music without the hassle of cords, wires, and jacks. But can Bluetooth give you an authentic hi-fi listening experience?
Bluetooth can’t be Hi-Fi, at least to most audiophiles. Many audiophiles insist that wired headphones and speakers sound better. That’s because a wire carries more data than a wireless connection. That information means a wired connection produces a more accurate sound without distortion.
But it all depends on what you consider Hi-Fi and as Bluetooth is constantly improving with better codecs, it might be a very considerable option for your needs.
This article examines the technology behind Bluetooth and the science behind psychoacoustics – the way we perceive and process sound. I’ll also explain what “hi-fi” means and talk about how you can get the best possible sound from your Bluetooth listening devices.
The History of Bluetooth
At the 1999 COMDEX conference, Ericsson, a Swedish mobile phone maker, introduced the first wireless headset. While the Bluetooth headset won the Best of Show Technology Award, the first Bluetooth phone (the Ericsson M39) only became available to consumers in 2001.
At first, customers showed little interest in Bluetooth because these devices were expensive. In 2001, analyst Peter Firstbrook asked, “Who’s going to pay $150 for a Bluetooth card when it’s not that inconvenient to pay much less and use a cord?” But as chip prices went down, demand rose. By 2009 manufacturers were producing 920 million Bluetooth chips each year.
Today we find Bluetooth devices everywhere. Your wireless keyboard, mouse, and printer all use Bluetooth to connect to your computer. 76.2% of all headphones sold in 2019 were wireless. Most headphone users are pretty content with the sound of their Bluetooth headphones. So why do a few others object? To answer that question, we need to learn a bit about how Bluetooth works.
How Bluetooth Works
Bluetooth uses short-range radio networks to transmit packets of data. Since most Bluetooth devices run on batteries, engineers design the transceiver chips for low-power usage. When two Bluetooth chips connect, they exchange information which they then pass on to their device.
Depending on the version, Bluetooth has a maximum transmission rate between 1-3 megabits per second. But a Bluetooth chip’s ability to process data — the application throughput — is lower. Headphones using Bluetooth 4.0LE can receive a music stream at 1MB per second. But they can only send that data to your ears at around 305kB (305,000 bits) a second.
That still sounds pretty fast, but a Spotify stream uses 320kB a second. And if you want to stream a CD recording, you will need 1,411kB/second! Your Bluetooth headphones are throwing away some of your data before they process it for listening.
The Bluetooth chip relies on an Advanced Audio Distribution Protocol (A2DP) to transform bits and bytes into music. Each of those A2DPs compresses the stream before turning it into sound. AAC and SBC, the A2DPs used by most wireless headphones, only sample at 320kB and 344kB, respectively.
What Is Hi-Fi?
In the summer of 1951, Milton Sleeper released the first issue of High Fidelity magazine. At that time, recordings were generally mediocre. Sound reproduction equipment was even worse. Sleeper and a growing number of “audiophiles” wanted their recorded music to sound more like a live performance.
In 1958, stereo recordings became available to consumers. WGFM (Schenectady, New York) began broadcasting in stereo at midnight on June 1, 1961; WEFM Chicago started their stereo broadcasts an hour later. As recording and production technology improved, audiophiles could listen to a much more accurate reproduction of the original signal.
But many were more interested in making their music portable. In 1979, the Sony Walkman cassette player brought better sound to a generation raised on AM transistor radios. Released in 2001, Apple’s iPod allowed listeners to carry lots of music in their pockets. People could now enjoy their favorite songs while doing errands or running chores. They didn’t care that the quality was less than the best (and most expensive) stereo equipment.
Some, however, still sought high fidelity. Audiophiles pay enormous sums for equipment that brings out every nuance of their recordings. Super Audio CDs (SACDs) promise more accuracy and dynamic range than compact disks. File formats like DSD and MQA preserve the original signal more faithfully than lossy (compressed) MP3 recordings.
There is undoubtedly a market for high-end audio and high-definition recordings. But do they sound that much better than lesser technologies?
Can You Hear the Difference?
A September 2007 blind test of Boston Audio Society members found that only 49.82% could distinguish between an SACD and a CD recording — a percentage no higher than random chance. A 2009 McGill University study found that average listeners had difficulty distinguishing between a CD and an MP3 compressed at more than 96kB. Experienced sound engineers preferred the CD even to 320kB MP3s.
A quick look at human hearing and music production will be helpful:
- Limits of Hearing: A young person can usually hear the sound spectrum between 20 to 20,000hz. Most adults cannot hear anything above 15,000hz. A CD can cover a frequency range of 20 to 20,000 Hz: an SACD goes to 50,000 Hz. The highest note on a piccolo or a piano, C8, is 4,186 hertz.
- Dynamic range is the difference between the quietest and loudest passages in a recording. CD recordings can capture 96 dB of dynamic range: an SACD has 120 dB; 24-bit digital audio has 144 dB. Orchestral music’s dynamic range is below 80 dB. Any piece which took full advantage of these limits would leave its audience deaf.
- Loudness Wars between record producers have further limited dynamic range. Because louder songs jump out in a playlist, many sound engineers record at maximum volume, then use dynamic sound compression (DSC) to make soft passages louder. No matter the medium, these songs will still range between loud, louder, and distorted.
The differences between a CD and a 320kB MP3 are so slight that only the most sensitive ears can detect them. The Boston Audio Society, a group of audiophiles, audio engineers, and musicians, struggled to distinguish between an SACD and a CD signal. Bluetooth may not be considered hi-fi by many audiophiles, but most people would not be able to hear the difference anyway.
Getting the Best Sound With Bluetooth
You can do a few things to improve your listening experience with Bluetooth equipment if you have problems. It may not be hi-fi, but these tips can help:
- Move closer to the source. Bluetooth has a 10-meter (32.81-foot) range. But it can be blocked by thick walls or heavy furniture. If your signal keeps dropping or skipping, something may be standing between you and your music.
- Turn off some apps. Your iPhone or computer may be running out of memory. GPS apps or syncing data can cut down on the available bandwidth and interfere with your music stream.
- Make sure your earbuds fit correctly. If you are using earbuds, you should use the tip, which is snug but not uncomfortable. Loose buds will give you inferior sound and may fall out of your ear.
- Comfortable headphones sound better. If you have an on-ear model, make sure the on-ear rest feels right. Over-ear headphones should completely cover your ear. Adjust until your headphones give you the best sound and the best fit.
- Buy the best headphones you can afford. Cheap headphones can sound tinny and distorted. Some of the best wireless headphones available include the Bose Quiet Comfort 700 and the Sennheiser Momentum 3. For the best in earbuds, try the Sony WF-1000XM3 or the Apple Airpods Pro.
Can Bluetooth be hi-fi? According to many audiophiles, no. But given the number of happy headphone users, Bluetooth works wonderfully for most people. The final decision lies with you and your ears.