7.07 Sound Practice Quiz

Pitch is determined by the frequency of the sound wave; a higher frequency produces a higher perceived pitch. The other properties affect aspects like loudness and propagation rather than pitch.

Sound waves rely on the vibration of particles in a material medium such as air, water, or solids in order to propagate. In the absence of a medium, like in a vacuum, there are no particles to transmit the vibration.

The correct relationship is given by v = f � - λ, which shows that the speed of a wave is the product of its frequency and its wavelength. This equation is fundamental in understanding how changes in frequency affect wavelength when speed is constant.

Loudness is directly related to the amplitude of a sound wave; a larger amplitude means the sound is louder. Frequency, on the other hand, determines the pitch of the sound.

Since the speed of sound is constant in a given medium, an increase in frequency results in a decrease in wavelength, as described by the formula λ = v/f. This inverse relationship is a key concept in wave physics.

Sound intensity is usually measured in decibels (dB), a logarithmic unit that expresses sound pressure levels. Although the physical intensity can be quantified in watts per square meter, decibels are standard in practical and perceptual terms.

The Doppler Effect is the phenomenon that explains the apparent change in pitch when there is relative motion between a sound source and an observer. As the source approaches, the sound waves are compressed, increasing the frequency; as it recedes, the waves are stretched out, lowering the frequency.

The energy of a sound wave is proportional to the square of its amplitude, making amplitude the property most directly related to its energy. Frequency determines pitch and does not directly influence the energy transmitted.

Sound waves in air are longitudinal waves that propagate through a series of compressions (high-pressure regions) and rarefactions (low-pressure regions). This process transmits energy through the medium without permanently displacing the particles.

In water, molecules are closer together than in air, which allows sound waves to be transmitted more effectively. The increased density paired with the elastic properties of water contributes to the faster speed of sound.

An organ pipe is designed to produce standing waves and clearly demonstrates the formation of nodes and antinodes due to resonance. This makes it an ideal instrument for observing the fundamental principles of sound wave interference and harmonics.

Sound intensity is proportional to the square of the amplitude. Therefore, when the amplitude is doubled, the intensity increases by a factor of four, demonstrating a quadratic relationship.

Resonance occurs when an object is driven by an external frequency that matches its natural frequency, causing it to vibrate with increased amplitude. This phenomenon explains effects such as amplified sound in musical instruments and even the shattering of materials under certain conditions.

When air temperature increases, the molecules move faster, which facilitates quicker transmission of sound energy. This causes the speed of sound in air to increase.

Using the formula λ = v/f, substituting 343 m/s for v and 686 Hz for f gives λ = 343/686, which equals 0.5 m. This calculation reinforces the fundamental relationship between speed, frequency, and wavelength.

The interference of two sound waves with close, but not identical, frequencies leads to the phenomenon known as beats. This results in a periodic variation in sound intensity as the waves alternately constructively and destructively interfere.

For a tube open at both ends, the wavelength for the nth harmonic is given by λ = 2L/n. For the second harmonic (n=2), this simplifies to λ = L. This relation is key in understanding standing wave patterns in resonant systems.

The human ear perceives changes in frequency as differences in pitch. Although loudness, timbre, and duration are important aspects of sound, frequency specifically determines how high or low a sound is heard.

When two coherent sound waves of equal amplitude are exactly out of phase, they cancel each other out perfectly, resulting in a net amplitude of zero. This is a clear demonstration of destructive interference as predicted by the superposition principle.