Waveform
The waveform is the most fundamental way to visualize sound. It plots the amplitude of the signal against time, giving a direct view of the recorded audio in the time domain.
Basic Principles
A waveform represents sound as a sequence of samples — measurements of air pressure (more precisely, of the displacement from atmospheric pressure) taken at regular intervals. Each sample is stored as a number scaled into the range -1 to +1, where the extremes correspond to the loudest signal the file format can represent.
The number of samples per second is the sampling rate. CD-quality audio uses 44 100 samples per second; studio recordings often use 48 000, 96 000, or 192 000.
Two Views of the Same Signal
What the waveform shows depends on the zoom level.
- Oscilloscope view
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At extreme zoom, each sample becomes visible as a point, and the connecting line traces the actual shape of the wave. This view reveals the periodicity of a held tone, lets you spot discontinuities or artifacts in the recording, and is useful for studying the very first cycles of a note’s attack.
- Aggregated view
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When zoomed out, a single screen pixel covers many samples. Rather than picking one sample arbitrarily, the waveform aggregates the samples within that pixel’s time range and draws two things:
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the maximum and minimum values within the range — the outer envelope of the signal;
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the RMS (root mean square) value, drawn closer to the centerline, which tracks perceived loudness more closely than the peaks alone.
Aggregation makes it easy to see overall dynamics, identify louder and quieter sections, and locate specific events in long recordings.
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Reading the Waveform
The horizontal axis is time, from earlier on the left to later on the right. The vertical axis is amplitude, with 0 at the centerline (silence) and ±1 at the extremes — the maximum the file format can encode. When the signal would exceed those limits, samples are cut off at ±1, producing distortion known as clipping.
Relationship to Other Views
The waveform shows the overall intensity of the signal but not its frequency content; the Spectrum and Spectrogram reverse that emphasis. Sudden amplitude changes — note onsets, plosive consonants, glottal closures on the EGG — are typically more obvious on the waveform than on the spectrogram.
In VoceVista
See Timeline and Waveform for how to display and navigate the Waveform and the Timeline, including the available display modes and the linear/logarithmic amplitude scales.