نسخة المستند (8)

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• A sound wave describes the alternating increases and decreases of pressure that move through a medium.

molecular movement.

Wave motion is characterized by minimal movement of individual molecules and potentially extensive propagation of the changes in pressure that are created by the molecular movement.

Aperiodic wave

is a wave in which every cycle takes the same amount of time to occur as every

other cycle.

aperiodic wave

A wave in which individual cycles do not take the same amount of time to occur

is called aperiodic wave (without a period).

Why?

Because this type of sound does not have a specific period, by definition, it cannot have a specific frequency, or a specific pitch.

• Perceptually, such a wave sounds like noise.

Wavelength

Sound waves travel through space.

• The measurement of the distance traveled by a sound wave is its wavelength (λ).

• Wavelength refers to the distance in meters or centimeters covered by one complete

cycle of pressure change-that is, the distance covered by the wave from any starting point

to the same point on the next cycle.

Frequency, period, and wavelength are closely related.

• The higher the frequency (the more cycles per second), the shorter in duration is the

period and the shorter is the wavelength.

• The lower the frequency (the fewer cycles per second), the longer in duration is the

period and the longer is the wavelength.