Digital musicians rely on sample libraries to deliver pristine, realistic instrument sounds. But a persistent bug in MuseScore's popular MuseSounds library demonstrates how even meticulously crafted virtual instruments can harbor unexpected artifacts. Users recently identified an audible cough embedded within the Alto Saxophone's staccato articulation for concert E4 notes.

The Unwanted Performance

As detailed in GitHub issue #21426, the artifact manifests most clearly on half-note staccatos at soft dynamics (mp to ppp). The cough is clearly audible in one of the round-robin samples—a technique where multiple recordings of the same note are cycled to avoid mechanical repetition. Shorter note durations partially mask the artifact, but a fragment remains audible.

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Demonstration of the cough artifact in MuseScore (Source: GitHub Issue #21426)

Why This Matters Beyond a Single Note

  1. Round-Robin Vulnerability: This issue highlights how round-robin implementations—critical for natural-sounding instruments—can become vectors for undetected flaws. A single contaminated sample among dozens can surface unpredictably.

  2. Dynamic-Dependent Defects: The artifact's visibility only at softer dynamics underscores the complexity of velocity-layered sampling. Bugs may lurk in less frequently tested dynamic ranges.

  3. QA Challenges for Large Libraries: With thousands of samples in professional instrument libraries, manual quality control becomes astronomically difficult. This cough likely slipped through because it occupies a narrow slice of the parameter space (specific pitch, articulation, and dynamic range).

The Bigger Picture for Audio Developers

While humorous on the surface, this bug is a case study in audio pipeline rigor. As one commenter noted, "It’s a stark reminder that sample libraries are human creations, complete with human imperfections." For developers working on digital audio:
- Automated anomaly detection in sample sets needs advancement
- Dynamic/articulation edge cases require more systematic stress-testing
- Community bug reports remain invaluable for catching elusive artifacts

The MuseScore team has acknowledged the issue, labeling it a medium-priority bug. Its resolution will involve not just replacing one sample, but examining how such artifacts evade detection—a process that could strengthen quality assurance for all sampled instruments.