Ask what the display can actually prove
Before you begin: A short audio file you own and Audacity. No uploads are required.
A waveform displays amplitude over time. A spectrum estimates how energy is distributed by frequency over a selected interval. They answer different questions. Neither identifies the performer, recording location or instrument with certainty.
Keep your original file and examine a copy. Record its duration, sample rate and channels before editing. Then select a steady region and compare its spectrum with a transient region. Selection length and analysis settings influence the picture.
Worked example & observations
Original synthetic fixture: generate a 440 Hz sine tone, then a 440 Hz square tone at a modest level. Plot each spectrum using the same settings. The sine should concentrate energy near one frequency; the square has additional harmonic structure. A finite selection and window can spread peaks, so do not expect one perfect vertical line.
Your turn
A large peak appears near 440 Hz. Does it prove the sound is a violin playing A4? What extra evidence would you need?
Show answer and reasoning
No. Many sources can produce energy there, and the peak need not be the fundamental. Inspect harmonics, timing and context, and listen to the recording. Even that may not uniquely establish an instrument; provenance is stronger evidence of who or what was recorded.
Watch for: Louder waveforms are not automatically higher-quality audio. A flat-topped waveform can suggest clipping, but display scale and processing must be considered.
Published and planned
Published: this starter lesson, worked example and exercise with an answer.
Planned: An AUWEN file inspector; these instructions currently use a separate desktop editor.
Validation: source review and mathematical checks where applicable. Photography captures, audio listening and device workflows have not been performed for these lessons. Synthetic cases are labelled; no personal media or field observations are implied.
References
Original AUWEN teaching and examples. Sources reviewed 14 September 2026.
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