The photoacoustic hypothesis provides an alternative explanation for this longstanding mystery about generation of concurrent sounds by fireballs.Ĭoncurrent sound associated with very bright meteors manifests itself as popping, hissing, and faint rustling sounds occurring simultaneously with the arrival of the light from the meteor 1, 2, 3, 4, 5, 6, 7. Calculations show that −12 brightness meteors can generate audible sound at ~25 dB SPL. This heating produces small pressure oscillations in the air contacting the absorbers. Strongly modulated light at these frequencies with sufficient intensity can create concurrent sounds through radiative heating of common dielectric materials like hair, clothing, and leaves. Recent photometric measurements of fireballs reveal strong millisecond flares and significant brightness oscillations at frequencies ≥40 Hz. Herein we describe experimental results and numerical models in support of photoacoustic coupling as the mechanism. This has not been well validated experimentally. Previously, energy propagated from meteors was assumed to be RF emissions. Concurrent sounds must be associated with some form of electromagnetic energy generated by the meteor, propagated to the vicinity of the observer, and transduced into acoustic waves. These sounds cannot be attributed to direct acoustic propagation from the upper atmosphere for which travel time would be several minutes. Numerous instances have been documented with −11 to −13 brightness. Concurrent sound associated with very bright meteors manifests as popping, hissing, and faint rustling sounds occurring simultaneously with the arrival of light from meteors.
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