About the Quality Analyzer
Many FLAC and WAV files sold or shared online are fake: they were made from MP3 or AAC files and then saved in a lossless format. They are large but sound no better than the lossy original.
Lossy encoders remove high frequencies above a fixed cutoff. SoundBench measures the spectrum of the whole track, finds that cutoff and tells you which source quality it points to. It also checks for upsampled hi-res and for 24-bit files that only contain 16 bits of real data.
How to use the Quality Analyzer
- Add a FLAC, WAV, ALAC, AIFF or any other audio file.
- Read the verdict and the detected frequency cutoff.
- Check the spectrogram for a hard horizontal edge, which is the sign of lossy compression.
Typical frequency cutoffs by source
| Source | Typical cutoff |
|---|---|
| MP3 128 kbps | ≈ 16–17 kHz |
| MP3 192 kbps | ≈ 18.5–19 kHz |
| MP3 256–320 kbps, AAC 256 kbps | ≈ 19.5–20.5 kHz |
| Genuine CD-quality lossless | ≈ 21–22 kHz |
| Genuine hi-res (96 kHz) | Content above 24 kHz |
Other measurements
- Integrated loudness in LUFS (ITU-R BS.1770), the measure streaming services use for loudness normalization.
- Sample peak in dBFS and the number of clipped runs.
- Crest factor, a quick indicator of how heavily a track was compressed in mastering.
- Stereo correlation and dual-mono detection.
- Padded bit depth: 24-bit files whose lowest 8 bits are always zero.
Frequently asked questions
How can I tell if a FLAC is fake?
Look at its spectrum. A real CD-quality FLAC has content up to about 21–22 kHz. A FLAC made from an MP3 shows a sharp cutoff at 16–20 kHz, with almost nothing above it.
Is a 20 kHz cutoff always fake?
Not always. Some studio masters are low-passed near 20 kHz, so a cutoff just below 20.5 kHz is a strong hint rather than proof. Cutoffs at 16–19 kHz are a reliable sign of a lossy source.
How do I check if hi-res audio is real?
A real 96 kHz recording has some content above 22–24 kHz. If the spectrum stops at 20–22 kHz, the file was upsampled from CD quality.