engineering

High-resolution audio

High-resolution audio is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand High-resolution audio rather than just read about it. In short: High-resolution audio is a term for music files with bit depth greater than 16-bit and sampling frequency higher than 44.1 kHz or 48 kHz used in CD and DVD formats. The Audio Engineering Society (AES), Consumer Technology Association (CTA) and Japan Audio Society (JAS) set 24-bit/96 kHz as the minimum requirement to fulfill the standard.

Key takeaways

High-resolution audio belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect High-resolution audio to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of High-resolution audio from memory before moving on to harder problems.

Reference excerpt

High-resolution audio is a term for music files with bit depth greater than 16-bit and sampling frequency higher than 44.1 kHz or 48 kHz used in CD and DVD formats. The Audio Engineering Society (AES), Consumer Technology Association (CTA) and Japan Audio Society (JAS) set 24-bit/96 kHz as the minimum requirement to fulfill the standard. The Recording Academy Producers & Engineers Wing also cites 24-bit/96 kHz as the preferred resolution for tracking, mixing and mastering audio. In 2011, the Library of Congress chose 24-bit/96 kHz as the "international standard" for archiving and preserving its collection of historical recordings. It is supported by media formats such as DVD-Audio, DualDisc and High Fidelity Pure Audio, download stores like Bandcamp, HDtracks and Qobuz, and streaming platforms including Apple Music, Amazon Music and Tidal. Research into high-resolution audio began in the late 1980s and recordings were made available on the consumer market in 1996. Other bit depth/sample rate combinations that are often marketed as "high-resolution" include 1-bit/2.8224 MHz (DSD), 20-bit/44.1 kHz (HDCD), 24-bit/44.1, 88.2 or 176.4 kHz, 24-bit/48, 96 or 192 kHz, and 24-bit/352.8 kHz (DXD). Reference-grade digital-to-analog converters that oversample to very high rates such as 24-bit/384 kHz, 32-bit/384 kHz and 32-bit/768 kHz are also available for both consumer and professional use. Sony's LDAC, Dolby's Digital Plus and Lenbrook's MQA are marketed as "hi-res," however, these codecs employ lossy compression and can often have lower bit rates than Compact Disc Digital Audio, and thus, cannot be classified as "true high-resolution."

Definitions

High-resolution audio is generally used to refer to audio files that have a higher sample rate and/or bit depth than that of Compact Disc Digital Audio (CD-DA), which operates at 44.1 kHz/16-bit. The Recording Industry Association of America (RIAA), in cooperation with the Consumer Electronics Association, DEG: The Digital Entertainment Group, and The Recording Academy Producers & Engineers Wing, formulated the following definition of high-resolution audio in June 2014: "lossless audio capable of reproducing the full spectrum of sound from recordings which have been mastered from better than CD quality music sources which represent what the artists, producers and engineers originally intended." File formats capable of storing high-resolution audio include FLAC, ALAC, WAV, AIFF, MQA and DSD (the format used by SACD).

History

One of the first attempts to market high-resolution audio was High Definition Compatible Digital in 1995, an encoding/decoding technique using standard CD audio. This was followed by two more optical disc formats claiming sonic superiority over CD-DA: SACD in 1999, and DVD-Audio in 2000. These formats offer additional benefits such as multi-channel surround sound. Following a format war, none of these achieved widespread adoption. Following the rise in online music retailing at the start of the 21st century, high-resolution audio downloads were introduced by HDtracks starting in 2008. Further attempts to market high-resolution audio on optical disc followed with Pure Audio Blu-ray in 2009, and High Fidelity Pure Audio in 2013. Competition in online high-resolution audio retail stepped-up in 2014 with the announcement of Neil Young's Pono service. In 2014, the Japan Electronics and Information Technology Industries Association (JEITA) announced a specification and accompanying "Hi-Res AUDIO" logo for consumer audio products, administered by the Japan Audio Society (JAS). The standard sets minimums of 96 kHz sample rate and 24-bit depth, and for analog processes, 40 kHz. The related "Hi-Res Audio Wireless" standard certifies lossy audio codecs that meet the standard for high-resolution audio. Currently only LDAC, LHDC, LC3plus, MQair, SHDC, and aptX Adaptive are certified. Sony reaffirmed its commitment to development in the high-resolution audio segment by offering a slew of Hi-Res Audio products.

Streaming services As of 2021, some music streaming services such as Tidal, Qobuz, Amazon Music, and Apple Music have options to enable the playback of high-resolution audio files.

Controversy

Whether there is any benefit to high-resolution audio over CD-DA is controversial, with some sources claiming sonic superiority:

"The DSD process used for producing SACDs captures more of the nuances from a performance and reproduces them with a clarity and transparency not possible with CD."—The Mariinsky record label of the Mariinsky Ballet (formerly Kirov Ballet), St. Petersburg, Russia, that sells Super Audio CDs (SACDs) "The claimed main-benefit of high-resolution audio files is superior sound quality [...] 24-bit/96 kHz or 24-bit/192 kHz files should, therefore, more closely replicate the sound quality that the musicians and engineers were working with in the studio."—What Hi-Fi? "...music professionals with access to first generation data have widely reported subjectively better sound, and a meta-analysis of previously published listening tests comparing high resolution to CD found a clear, though small, audible difference that significantly increased when the listening tests included standard training (i.e., with experience in listening)."—Journal of the Audio Engineering Society, Volume 67, Issue 5 ...and with other opinions ranging from skeptical to highly critical:

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with High-resolution audio

Start with the simplest possible case. Write down what High-resolution audio claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to High-resolution audio before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about High-resolution audio ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of High-resolution audio

In research: High-resolution audio appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses High-resolution audio in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: High-resolution audio is common in secondary-school and first-year university syllabi. It links to neighbouring topics Audio engineering, Digital audio, Sound, so understanding it makes those chapters shorter.
In everyday life: Look for High-resolution audio outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study High-resolution audio in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what High-resolution audio means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain High-resolution audio out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is High-resolution audio in simple terms?

Why does High-resolution audio matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study High-resolution audio?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on High-resolution audio.