What causes the sound of a fire crackling?

Introduction

The sound of a fire crackling is a familiar and intriguing phenomenon. Understanding the mechanisms behind this sound involves exploring the physical processes that generate similar crackling noises in different contexts, such as jet engines and human respiratory systems.

Key Insights

Intense, Short-Duration Compressive Elements:
- Crackling sounds are caused by intense, spasmodic, short-duration compressive elements of the waveform. These elements have low energy spread over a wide frequency range and occur randomly.
Sudden Opening and Closing Events:
- In the context of respiratory sounds, crackles are generated by sudden airway closure events during expiration and explosive opening events during inspiration. This mechanism is consistent with the stress-relaxation quadrupole hypothesis.

Conclusion

The crackling sound of a fire is likely caused by intense, short-duration compressive elements that occur randomly, similar to the mechanisms observed in jet noise and respiratory crackles. These sounds are produced by sudden, spasmodic events that generate a wide range of frequencies, creating the characteristic crackling noise.

What causes the sound of a fire crackling?

Summary

Introduction

Key Insights

Conclusion

Sources and full results

‘Crackle’: an annoying component of jet noise

'Crackle' in jet noise is caused by intense spasmodic compressive elements, and its intensity varies with jet velocity and angular position, but not jet scale, jet temperature, or combustion.

Mechanism of inspiratory and expiratory crackles.

Crackle generation is likely caused by sudden airway closing during expiration and sudden airway reopening during inspiration.

Anomalous Sounds and Electromagnetic Effects Associated with Fireball Entry

Anomalous sounds and electromagnetic effects associated with fireball entry may be caused by electric discharges near the observer, geopotential disturbances, or strong electromagnetic radiations from the fireball.

Change in acoustic impulse response of a room due to a fire.

A room fire causes wave-fronts to arrive earlier, with higher sound speed, and shifts modes up in frequency, significantly attenuating high-frequency modes.

Crackles and wheezes.

Crackles and wheezes are caused by the explosive opening of airways in deflated lung regions, and their pitch is largely determined by the linear velocity of air passing through narrowed airways.

Physical and acoustic response of Pinus palustris to fire

Long leaf pine (Pinus palustris) in grass-stage exhibits unique acoustic and mechanical responses to low-intensity fire, providing valuable information for land managers and wildland fire fighters.

Hearth and campfire influences on arterial blood pressure: defraying the costs of the social brain through fireside relaxation.

Hearth and campfires induce relaxation through multisensory, absorptive, and social experiences, reducing blood pressure and enhancing prosocial behavior.

On a fire extinguisher using sound winds

The sound fire extinguisher uses special sound winds to increase sound energy performance 10 times more effectively than traditional ones, reducing size and weight while maintaining effectiveness.

Sound of the Aurora

The sound of the aurora is like the crackling or rustling of blazing flames, and no one has ever seen or heard such strange sounds as these during an electric storm.

Frogs flee from the sound of fire

Reed frogs can detect fire sounds and flee to protective cover, a novel response not found in other animals, suggesting amphibian hearing evolved through sexual selection and a broader context.

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