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Frequency Cutoff Detection

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The AudioLens Blog

Deep dives into high-resolution audio, format comparisons, spectral analysis, and everything an audiophile needs to make informed purchases.

Guide Feb 20, 2026 12 min read

What Is High-Resolution Audio? The Complete Guide for 2026

High-resolution audio promises better-than-CD quality, but the marketing can be misleading. We break down sample rates, bit depths, and what actually matters for your listening experience — backed by spectral analysis, not buzzwords.

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Analysis Feb 14, 2026 9 min read

How to Spot Fake Hi-Res Files: Upsampling Detection Explained

Not every file labeled "24-bit/96kHz" was actually recorded at that resolution. Learn how spectrogram analysis reveals upsampled fakes and why frequency cutoff is the most reliable indicator of true quality.

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Comparison Feb 6, 2026 10 min read

FLAC vs WAV vs ALAC vs DSD: Which Lossless Format Should You Choose?

All lossless formats promise bit-perfect audio, but they differ in compression efficiency, metadata support, hardware compatibility, and streaming practicality. Here's a detailed comparison for every use case.

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Science Jan 28, 2026 8 min read

The Loudness War: How Dynamic Range Compression Ruined Your Favorite Albums

Modern mastering practices sacrifice dynamic range for perceived loudness. We analyze real spectrograms from different masters of the same recordings and show you exactly what's been lost.

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Buyer's Guide Jan 19, 2026 11 min read

Where to Buy Legitimate High-Res Audio in 2026: Stores, Streaming, and Red Flags

From Qobuz to Bandcamp to HDtracks, we review the major platforms for purchasing genuine high-resolution music files. Plus, the telltale signs that a store might be selling upsampled fakes.

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What Is High-Resolution Audio? The Complete Guide for 2026

Guide Feb 20, 2026 12 min read

The term "high-resolution audio" gets thrown around a lot in marketing materials, but what does it actually mean? At its core, hi-res audio refers to any digital audio format that surpasses the quality of standard CD audio, which is defined as 16-bit depth at a 44.1 kHz sample rate.

Understanding Sample Rate

Sample rate determines how many snapshots of an audio signal are captured per second. CD audio at 44.1 kHz captures 44,100 samples every second, which according to the Nyquist theorem can reproduce frequencies up to 22.05 kHz — just above the accepted upper limit of human hearing at around 20 kHz.

Hi-res sample rates like 88.2, 96, 176.4, and 192 kHz capture audio at two to four times the CD rate. This extends the theoretical frequency ceiling to 48 kHz or even 96 kHz. Whether humans can perceive audio content at these ultrasonic frequencies remains debated, but higher sample rates also provide steeper anti-aliasing filter roll-offs within the audible band, which some engineers argue produces cleaner transient reproduction.

Bit Depth: Beyond 16-bit

While sample rate determines frequency range, bit depth determines dynamic range — the span between the quietest and loudest sounds a file can represent. Each additional bit doubles the number of possible amplitude levels.

A 16-bit file offers roughly 96 dB of dynamic range, which is more than adequate for most listening environments. Moving to 24-bit expands this to approximately 144 dB — well beyond the threshold of pain (around 120 dB) and far exceeding what any playback system can reproduce. The practical benefit of 24-bit for consumers is debatable, but it's invaluable during recording and mixing where headroom prevents digital clipping.

The Real Question: Can You Hear the Difference?

This is where things get contentious. Numerous double-blind studies have struggled to demonstrate that listeners can reliably distinguish between a well-mastered CD-quality file and its hi-res counterpart. The audible improvements people report often stem from the mastering itself — hi-res releases frequently get more careful, dynamic mastering compared to their compressed CD or streaming counterparts.

That said, the audiophile argument isn't just about perceptible frequency content above 20 kHz. Proponents point to improved timing resolution, more natural filter behavior, and better preservation of phase relationships across the audible band.

How AudioLens Helps

Rather than taking a file's metadata at face value, AudioLens performs actual spectral analysis using FFT (Fast Fourier Transform) to examine exactly where audio content exists in the frequency domain. This lets you verify whether a "96 kHz" file genuinely contains ultrasonic content or is simply an upsampled CD-quality recording packed into a larger container.

The most reliable indicator of true hi-res content is the frequency cutoff — where spectral energy actually drops to the noise floor. A genuine 96 kHz recording should show content well above 22 kHz. An upsampled fake will show a sharp cliff right at the CD Nyquist boundary.

What to Look For

When evaluating a hi-res file, there are several key indicators. The spectrogram should show gradual, natural energy rolloff at high frequencies rather than an abrupt brick-wall cutoff. The bandwidth usage percentage should reflect actual content filling a significant portion of the available frequency range. And the dynamic range metrics should show good crest factor values, indicating the mastering hasn't crushed the dynamics that make hi-res meaningful in the first place.

In the end, the most honest approach is empirical: analyze your files, trust the data, and let your ears make the final call in your own listening environment with your own equipment.

How to Spot Fake Hi-Res Files: Upsampling Detection Explained

Analysis Feb 14, 2026 9 min read

You've just paid a premium for a 24-bit/96 kHz FLAC album from an online store. The file sizes are impressive, the metadata looks right, and your DAC's display proudly shows "96 kHz." But is the audio actually high-resolution? Unfortunately, the answer is sometimes no.

What Is Upsampling?

Upsampling is the process of increasing a file's sample rate after the fact — taking a 44.1 kHz recording and converting it to 96 kHz, for example. The resulting file is technically at a higher sample rate, but no new audio information has been added. The additional samples are mathematically interpolated from the original data. It's the audio equivalent of enlarging a low-resolution photograph: the file gets bigger, but the detail doesn't improve.

Why Spectral Analysis Is the Definitive Test

A genuine 96 kHz recording captures microphone signals with content potentially extending to 48 kHz. When you view its spectrogram, you'll see energy — however faint — distributed across most of the frequency range, with a natural, gradual rolloff at the highest frequencies.

An upsampled file tells a completely different story. Because the original recording was band-limited to 22.05 kHz (the Nyquist frequency of 44.1 kHz), no amount of upsampling can create real spectral content above that boundary. The spectrogram will show a stark, unmistakable wall of silence above approximately 22 kHz.

The Lossy Transcode Problem

Even more egregious than upsampling is the practice of transcoding a lossy file into a lossless container. Someone takes an MP3 at 128 kbps — which cuts off around 16 kHz — and re-encodes it as FLAC or WAV. The file appears lossless, but the spectral signature is unmistakable: a hard frequency cutoff well below even CD-quality range.

AudioLens specifically checks for this pattern. When it detects a lossless container format but finds spectral content cutting off in the 15–18 kHz range, it flags the file as a probable lossy transcode. This is one of the most common scams in online music stores, and it's trivially detectable with proper spectral analysis.

How AudioLens Detects It

Our detection algorithm works by scanning the averaged frequency spectrum from high frequencies downward. Rather than looking at individual frequency bins (which can be fooled by stray harmonics), we use a wide analysis window with median filtering. This means a handful of spectral spikes won't trigger a false positive — we require sustained, broadband energy to confirm that real audio content exists at a given frequency.

The algorithm also considers the ratio between detected cutoff frequency and the file's Nyquist frequency. A genuine hi-res file should show content extending well above the CD Nyquist boundary of 22.05 kHz. If it doesn't, the file is flagged with the appropriate level of certainty.

The golden rule: if a 96 kHz file shows no spectral content above 22 kHz, you're looking at an upsampled CD — not genuine high-resolution audio.

FLAC vs WAV vs ALAC vs DSD: Which Lossless Format Should You Choose?

Comparison Feb 6, 2026 10 min read

If you've committed to lossless audio, you've already made the most important decision: no more discarding audio data for the sake of file size. But within the lossless world, you still have choices to make. Each format has its own strengths, trade-offs, and ideal use cases.

WAV: The Uncompressed Standard

WAV (Waveform Audio File Format) stores raw PCM data with no compression whatsoever. What goes in comes out, bit for bit, with no processing required for playback. This makes it the simplest format to decode and the most universally compatible. Nearly every device, DAW, and player supports WAV natively.

The downside is size. A stereo 24-bit/96 kHz WAV file consumes roughly 34 MB per minute. WAV also has limited metadata support — while BWF (Broadcast WAV) extensions exist, tagging support across players is inconsistent. For archiving a large collection, the lack of compression becomes impractical quickly.

FLAC: The Audiophile Favorite

FLAC (Free Lossless Audio Codec) compresses audio losslessly, typically reducing file sizes by 30–60% compared to WAV while guaranteeing bit-perfect reconstruction on playback. It supports metadata, album art, sample rates up to 655.35 kHz, and bit depths up to 32-bit. It's open-source, royalty-free, and supported by the vast majority of hardware and software players.

For most audiophiles, FLAC is the default recommendation. It combines excellent compression with universal support and rich metadata. The only notable holdout is Apple's ecosystem, which historically favored ALAC.

ALAC: Apple's Answer

Apple Lossless Audio Codec delivers compression ratios comparable to FLAC and has been open-sourced since 2011. Its primary advantage is native support across Apple devices, iTunes, and the Apple Music ecosystem. If your playback chain is Apple-centric, ALAC avoids the need for third-party apps or format conversion.

Outside the Apple ecosystem, ALAC support is patchier. Most modern players handle it, but FLAC remains more universally supported. Sound quality between FLAC and ALAC is identical — both are bit-perfect lossless formats. The choice between them is purely practical.

DSD: The Niche Contender

Direct Stream Digital takes a fundamentally different approach. Instead of PCM's multi-bit amplitude snapshots, DSD uses a 1-bit stream at extremely high sampling rates (2.8 MHz for DSD64, 5.6 MHz for DSD128, and higher). Originally developed for Super Audio CD (SACD), DSD has a devoted following who praise its analog-like quality.

DSD's challenges are significant: file sizes are enormous, editing requires conversion to PCM, hardware support is limited to specialized DACs, and the format itself is controversial among engineers. Many argue that any audible superiority comes from the careful mastering these releases typically receive, not from inherent format advantages.

Our Recommendation

For the vast majority of audiophiles, FLAC is the right choice. It's open, lossless, well-compressed, richly tagged, and plays on virtually everything. Use WAV for production work where universal raw compatibility matters. Choose ALAC if you're deeply embedded in Apple's ecosystem. And explore DSD if you have the hardware, the curiosity, and the storage space to spare.

The Loudness War: How Dynamic Range Compression Ruined Your Favorite Albums

Science Jan 28, 2026 8 min read

Listen to a vinyl pressing of a classic 1970s rock album, then play the 2010s remaster. Same songs, same performances — but something feels different. The remaster is louder, punchier, more immediately impactful. It also sounds more fatiguing, less dynamic, and somehow flatter despite being objectively louder. Welcome to the loudness war.

What Happened?

Starting in the mid-1990s, mastering engineers came under increasing pressure to make records louder. The logic was simple: in a casual A/B comparison, louder sounds better. Radio stations, streaming playlists, and CD players presented music back-to-back, and labels wanted their tracks to jump out. The tool of choice was aggressive dynamic range compression combined with brick-wall limiting.

Dynamic range compression narrows the gap between the quietest and loudest moments in a recording. A drum hit that should leap out of the mix gets squashed down; the quiet verse between choruses gets pushed up. The result is higher average loudness at the cost of musical dynamics.

What the Spectrogram Shows

AudioLens measures this through two key metrics. The crest factor represents the difference between peak level and RMS (average) level. A well-mastered recording typically has a crest factor above 10–12 dB, meaning there's real contrast between loud and soft. Loudness war casualties often measure below 6 dB — the waveform looks like a solid block rather than a dynamic signal.

The clipping indicator is equally telling. Aggressive limiting pushes peaks to 0 dBFS (digital full scale), and if the engineer pushed too hard, actual samples hit the ceiling. AudioLens counts these clipped samples and reports the percentage. Any value above 0.01% warrants concern.

Is There Hope?

Thankfully, the tide has turned somewhat. The widespread adoption of loudness normalization by streaming platforms (Spotify, Apple Music, YouTube, Tidal) has removed much of the incentive to master hot. When every track gets normalized to roughly the same loudness regardless of mastering level, crushing your dynamics actually makes your track sound worse, not better.

Some labels have begun releasing "dynamic" or "audiophile" masters alongside standard releases. These versions preserve the original dynamic range and are often available in hi-res formats. For audiophiles, seeking out these versions is one of the most impactful things you can do for your listening experience — far more impactful than chasing higher sample rates or bit depths.

A 16-bit/44.1 kHz FLAC with excellent dynamic mastering will sound better than a 24-bit/192 kHz file mastered in the loudness war. Format is secondary to the quality of the mastering.

Where to Buy Legitimate High-Res Audio in 2026: Stores, Streaming, and Red Flags

Buyer's Guide Jan 19, 2026 11 min read

The market for downloadable high-resolution audio files has matured considerably, but quality varies wildly between platforms. Some stores rigorously verify their source material; others simply upsample CD-quality masters and slap a "Hi-Res" label on them. Here's how to navigate the landscape.

Trusted Platforms

Qobuz

Qobuz has established itself as the gold standard for hi-res audio purchases. Based in France, they offer both streaming and downloads up to 24-bit/192 kHz, and they work directly with labels to source genuine hi-res masters. Their editorial content and provenance information help buyers understand what they're getting. If a recording is only available in CD quality, Qobuz says so rather than upsampling it.

Bandcamp

Bandcamp is unique because artists upload their own source files. This means quality depends entirely on the artist, but it also means you're as close to the source as possible. Many independent artists and labels offer genuine hi-res downloads. The platform supports FLAC, ALAC, WAV, and other formats. Always check the format options before purchasing — if an artist only offers MP3, the source may not be hi-res.

HDtracks

One of the original hi-res download stores, HDtracks partners with major and independent labels to offer verified high-resolution content. Their catalog skews toward jazz, classical, and classic rock, though it's expanded significantly. They clearly label resolution tiers and have a generally good reputation for source quality.

Red Flags to Watch For

When shopping for hi-res audio, certain warning signs should make you skeptical. Be wary of stores where every single album is available at 24/192 regardless of era or genre — older recordings from the 1960s physically cannot have been recorded at those specs. Watch for prices that seem too good to be true; legitimate hi-res licensing costs more than standard digital. And always be skeptical of obscure stores with limited information about their sourcing practices.

The most reliable verification method is simply to analyze what you've purchased. Drop the file into AudioLens and check whether the spectral content actually matches the advertised resolution. A genuine 96 kHz file should show meaningful energy above 22 kHz. If it doesn't, you've likely bought an upsampled file and should consider requesting a refund.

Streaming vs Downloads

Services like Tidal, Apple Music, and Amazon Music now offer hi-res streaming tiers. These can be excellent for discovery, but for critical listening and archiving, downloads remain superior. Streaming quality can vary with network conditions, and you're dependent on the service's continued operation and licensing agreements. A purchased FLAC file is yours to keep and play in any environment.

The best investment in audio quality isn't a higher sample rate — it's knowing your source. Verify, analyze, and trust the data over the marketing.