Sonic Spectrum and Its Effects

Sonic Spectrum

• Sonic spectrum can be classified into three frequency ranges: infrasound, audible sound, and ultrasound, based on frequency and atmospheric pressure.
• Infrasound: less than 20Hz, produced by natural phenomena like earthquake waves and atmospheric pressure changes.
• Audible Sound: 20Hz to 20kHz, audible to the human ear.
• Ultrasound: greater than 20kHz.

Infrasonic Effect on the Human Body

• Infrasound can travel long distances without losing much power due to its low absorption and large wavelength.
• Infrasound can travel through most media, making it difficult to minimize its effects.
• Intense infrasonic noise causes clear symptoms including respiratory impairment and aural pain.
• Other potential effects include fear, visual hallucinations, and chills.

Applications of Infrasound and Ultrasound

• Infrasound is used to study heart mechanical function through seismocardiograms.
• Ultrasound is used clinically in several specialties, providing more information than X-rays and being less hazardous to the fetus.

Intensity of a Sound Wave

• Intensity of a sound wave (I) is the energy carried by the wave per unit area and per unit time (W/m²).
• Intensity can be expressed by the maximum change in the wave per unit area and per unit time (W/m²).
• The characteristics of a substance affect the intensity of a sound wave, with factors including density (ρ), velocity (v), and acoustic impedance (Z).