Simple Explanation

A graph used to display the decay of sound frequencies over time, showing how a speaker or room responds to an impulse.

Concise Technical Definition

A Waterfall Graph, also known as cumulative spectral decay (CSD), is a three-dimensional plot used to display the frequency, amplitude, and time characteristics of a loudspeaker's impulse response or room decay. The horizontal axis represents frequency, the vertical axis shows amplitude, and the third axis (back-to-front) displays time. Waterfall plots are useful for analyzing how a speaker or room responds over time, particularly with regard to sound decay and room modes, revealing how long certain frequencies linger before dissipating.

Layman-Friendly Analogy

A waterfall graph is like watching how ripples in water fade away over time. Just as you can see the ripples lose strength and disappear as time goes on, a waterfall graph shows how sound frequencies fade after a loudspeaker produces them, with each ripple representing a different frequency. This helps us see how quickly and smoothly a speaker or room "cleans up" after a sound is made, without lingering echoes or distortions.

Industry Usage Summary

Waterfall plots are commonly used in audio engineering to analyze loudspeakers and room acoustics, particularly for identifying how sound frequencies decay over time. In loudspeakers, it helps engineers understand the impulse response and how quickly a speaker stops ringing after a sound is played. In room acoustics, waterfall plots are useful for studying room modes and reverberation times, which can highlight problem areas where sound frequencies linger or echo. This analysis is critical for both speaker design and optimizing room acoustics for clear and balanced sound.

Engineering Shortcut

A three-dimensional graph showing frequency, amplitude, and time decay of sound, used to analyze loudspeaker performance and room acoustics.

Full Technical Explanation

A Waterfall Graph or Cumulative Spectral Decay (CSD) plot is a three-dimensional graph used to visualize the decay characteristics of sound frequencies in a loudspeaker or room. It plots frequency on the horizontal axis, amplitude on the vertical axis, and time on the third axis (back-to-front), showing how the amplitude of each frequency decreases over time. Waterfall plots are crucial for understanding how quickly sound decays after being emitted by a loudspeaker or how room acoustics affect this decay. For loudspeakers, the graph reveals how long particular frequencies linger after the initial sound, which can indicate resonance or distortion. In room acoustics, it helps identify problematic room modes, revealing which frequencies are sustained due to reflections or poor room treatment. The analysis of these decays helps engineers improve sound clarity, reduce unwanted reverberations, and create more accurate audio experiences.