Sound Waves and Frequency Changes

A type of wave that moves in a repetitive, up-and-down pattern, resembling a sine function.

The maximum displacement of a point on a wave from its resting position.

The distance between two consecutive crests or troughs of a wave.

The number of wave cycles passing a fixed point per second.

The relationship between the speed of a wave, its wavelength and frequency: V = λf, where V is the speed, λ is the wavelength, and f is the frequency.

The change in direction of a wave as it passes from one medium to another, causing its speed to change.

The bouncing back of a wave off a surface. The angle of incidence equals the angle of reflection.

The spreading out of waves as they pass through an opening or around an obstacle. Explains why we can hear sounds around corners.

When two waves of the same frequency and amplitude combine, resulting in a wave with twice the amplitude.

When two waves of the same frequency and amplitude combine but are out of phase by 180 degrees, resulting in a wave with zero amplitude (cancellation).

A pattern of alternating bright and dark bands formed when light waves interfere with each other.

The specific location within a standing wave where the amplitude is zero.

The specific location within a standing wave where the amplitude is maximum.

A wave that appears stationary, formed when two waves of the same frequency and amplitude interfere while traveling in opposite directions.

The longest wavelength that can fit within a given space or on a string.

A wave with a wavelength that is a multiple of the fundamental wave.

Wave motion is the transfer of energy through a medium by a periodic disturbance.

A mechanical wave requires a medium (like air, water, or a rope) to travel. The disturbance causes particles in the medium to vibrate.

Waves that compress and expand the medium as they travel, like sound waves.

A phenomenon where two or more waves interact and create patterns of reinforcement (constructive interference) or cancellation (destructive interference).

The speed of sound in a medium is determined by the medium's properties (density, temperature), and the speed of sound is typically faster in denser mediums or at higher temperatures.

A change in the perceived frequency (pitch) of a sound wave due to the relative movement of the source and the observer.

The natural frequency at which an object vibrates, causing maximum amplitude of vibration. In this example, it's 1 Hz for the tail boom.

Multiple frequencies of vibration that are integer multiples of the fundamental frequency. In this example, 2 Hz is the first overtone for the tail boom.

A phenomenon where the frequency of a sound wave is close to the natural frequency of an object, causing the object to vibrate with a larger amplitude.

A state where a vibration reaches its maximum amplitude due to resonance. In the example, 20 RPM is a critical speed as it matches the tail boom's fundamental frequency.

When two sounds with slightly different frequencies interfere, creating a periodic variation in loudness.

The intensity of sound is determined by the amplitude of the sound wave. It's measured in decibels (dB).

Sound intensity decreases with the square of the distance from the source. Doubling the distance reduces intensity to one-fourth.

The frequency of a sound wave determines its pitch. Higher frequency means higher pitch.

A property of sound that distinguishes different sounds and is determined by the combination of harmonics present.

Numerical multiples of the fundamental frequency in a complex sound, adding to its unique timbre.

A dimensionless quantity representing the ratio of an object's speed to the speed of sound in the surrounding medium.

The condition when an object travels at a speed less than the speed of sound.

The condition when an object travels at a speed greater than the speed of sound.

A shock wave created when an object travels at or faster than the speed of sound, resulting in a loud boom.

Disturbances created by aircraft traveling at the speed of sound that pile up, creating a shock wave audible as a sonic boom.

The Doppler Effect describes the change in frequency (and thus pitch) of a sound wave due to relative motion between the source of the sound and the observer. As a source of sound moves towards an observer, the waves are compressed, leading to a higher frequency (higher pitch). When the source moves away, the waves are stretched out, resulting in a lower frequency (lower pitch).

The speed of sound is affected by the properties of the medium it travels through. In general, sound travels faster through denser media like solids than through gases like air. Temperature also plays a role: higher temperatures mean faster sound propagation.

Sound is produced by vibrations. Vibrations from a source cause disturbances in the surrounding medium, transmitting energy in the form of waves. These waves travel through the medium and reach our ears, where they're interpreted as sound.

Intensity is the power carried by a sound wave per unit area. It's what we perceive as loudness. Higher intensity corresponds to louder sounds.

Pitch refers to how high or low a sound appears to be. It's determined by the frequency of the sound wave. Higher frequency corresponds to higher pitch.