Echoes rearrange spectral energy without changing its total

Evidence

The echo is, to some extent, an original sound, and therein is the magic and charm of it. It is not merely a repetition of what was worth repeating in the bell, but partly the voice of the wood. — Gordon Hempton, John Grossmann, One Square Inch of Silence- One Man’s…, 927 (#complicates, via linked claim)

Categorization

• XREF: connects to: A returning echo creates power-spectrum peaks spaced by its inverse time — Eric J. Heller, Why You Hear What You Hear- An…, 1096; Impulse energy is fixed at impact regardless of later echoes; Whether echoes constructively add in Fourier analysis depends on wavelength relative to echo timing. (+2 more)

Related

• An echo is partly an original sound from the reflecting material (similarity 0.87)
• Reflections cannot introduce frequencies not present in the original sound (similarity 0.87)
• Reflecting surfaces cannot create new frequencies in ordinary echoes (similarity 0.86)
• A returning echo creates power-spectrum peaks spaced by its inverse time (similarity 0.85)
• Whether echoes constructively add in Fourier analysis depends on wavelength relative to echo timing. (similarity 0.84)
• Loudness-time functions reveal echoes and reverberation better than level-time ones (similarity 0.84)
• The fixed energy of an impulse forces increasing echoes to weaken proportionally. (similarity 0.83)
• Thirteenth-century physics intuited sound self-amplification through reflection. (similarity 0.82)
• Fourier analysis of echoes yields alternating strong and weak spectral bands (similarity 0.82)
• Echoes reshape but never change the total energy in a source spectrum (similarity 0.81)
• Echo interference creates sinusoidal power fluctuations that average to zero (similarity 0.79)
• Any echo-producing system inevitably exhibits frequency power fluctuations (similarity 0.78)

Broader Connections

• Whether echoes constructively add in Fourier analysis depends on wavelength relative to echo timing. #expands (0.85)
• Reflecting surfaces cannot create new frequencies in ordinary echoes #corroborates (0.80)
• An echo is partly an original sound from the reflecting material #complicates (0.75) — Gordon Hempton, John Grossmann, One Square Inch of Silence- One Man’s…, 927