Acoustics Exam Questions And Answers

The term "noise" refers to unwanted or unpleasant sound. In this context, "heavy metal rock" can be considered noise if it is unwanted or unpleasant to the listener. Similarly, "sound decay" can also be considered noise if it is an undesirable or disturbing sound. "Baby crying out loud" can be seen as noise if it is unwanted or irritating. Therefore, the correct answer is noise, as it encompasses all these examples of unwanted sound.

some situations, wood might be ideal.

Sound can travel under water because water is a denser medium compared to air. Sound waves require a medium to travel through, and water provides a more efficient medium for sound transmission. The molecules in water are closer together, allowing sound waves to propagate more effectively. This is why sounds can be heard underwater, such as the sound of waves or the calls of marine animals.

Using absorptive materials is the best way to reduce air-borne sound. Absorptive materials have the ability to absorb sound waves, preventing them from bouncing off surfaces and causing echoes or reverberation. By using these materials in a space, the sound energy is converted into heat energy, reducing the overall sound level and creating a quieter environment. This method is effective in reducing noise pollution and improving the acoustics of a room or building.

The range of sound that a human ear can detect is typically between 20 and 20,000 Hz. This range is often referred to as the audible frequency range. Sounds with frequencies below 20 Hz are considered infrasound and are typically felt rather than heard. Similarly, sounds with frequencies above 20,000 Hz are considered ultrasound and are also typically not heard by the human ear.

An echo is the repetition of a sound that occurs when sound waves bounce off a surface and return to the listener. The sound waves need to be loud enough and have a sufficient delay in order for the echo to be perceived as distinct from the original sound source. This phenomenon is caused by the reflection of sound waves off an obstructing surface. Therefore, the correct answer is echo.

To address the problem of acoustics in a showroom with an industrial look, it is recommended to install an acoustic ceiling. An acoustic ceiling can help absorb sound and reduce echo, creating a more pleasant and comfortable environment for customers. This solution is effective in improving the overall acoustic quality of the space and can be seamlessly integrated into the existing industrial aesthetic of the showroom.

Sound absorbers are materials that reduce the amount of sound energy reflected back into a space. They work by converting sound energy into heat through friction. Common examples of sound absorbers include corkboard, foam, Styrofoam, draperies, and carpets. These materials are often used in homes, offices, and studios to improve sound quality and reduce noise levels.

Frequencies below 20Hz are called infrasonic sound. Infrasonic sound refers to sound waves with frequencies lower than what the human ear can perceive. These frequencies are often produced by natural phenomena such as earthquakes, volcanic eruptions, and thunderstorms. Infrasonic sound can also be generated by man-made sources like machinery and explosions. Although humans cannot hear infrasonic sound, some animals are capable of detecting and responding to these low-frequency vibrations.

The term "sound subdivision" does not typically fall under the category of elements of acoustic. Acoustic elements usually refer to the components involved in the production, transmission, and reception of sound. These include the sound source, which generates the sound waves, the sound transmission path, which allows the sound to travel, and the sound receiver, which detects and converts the sound waves into audible signals. However, "sound subdivision" does not fit into this framework and is therefore not considered an element of acoustic.

The correct answer is dB because dB (decibel) is the unit used to measure the intensity or loudness of sound. It is a logarithmic unit that compares the sound pressure level to a reference level. The dB scale is commonly used in fields such as acoustics, telecommunications, and audio engineering to quantify sound levels.

Auditoriums rely on the sound absorption properties of the audience to create good acoustics. Sparsely spaced seats allow sound waves to diffract, or spread out, more easily, increasing the overall sound absorption in the room. This is because the gaps between seats allow sound waves to pass through and be absorbed by the audience, reducing echo and reverberation. Therefore, the statement that sparsely spaced seats provide greater sound absorption than closely spaced seats due to the diffraction effect is true.

Echoes are reflected sounds. When sound waves encounter a surface, they bounce back and return to the source. This phenomenon is known as reflection. Echoes occur when the reflected sound waves reach our ears after bouncing off a surface, creating a distinct repetition of the original sound.

Carpet tile is the best flooring material for a music hall with a lot of audience because it provides sound absorption, reducing echo and improving acoustics. It also offers comfort underfoot, making it more enjoyable for people to stand or walk on for long periods. Additionally, carpet tile can be easily replaced if damaged or stained, ensuring the music hall maintains a clean and attractive appearance.

Resonance refers to the intensification and prolongation of sound produced by sympathetic vibration. When an object vibrates at its natural frequency, it can cause another object with the same natural frequency to vibrate as well. This phenomenon is known as resonance. In the context of the given question, resonance is the most suitable answer as it accurately describes the process of sound intensification and prolongation through sympathetic vibration.

Reverberation refers to the persistence of sound in a particular space after the original sound is produced. It is caused by multiple reflections of sound waves off surfaces in the environment. This phenomenon creates a prolonged and slightly modified sound that can be heard after the initial sound source has stopped. Echo, sound reflections, and vibration are related concepts, but they do not specifically refer to the persistence of sound in a space like reverberation does.

Rectangular rooms with flat parallel walls have poor diffusion because sound waves tend to bounce back and forth between the walls, creating standing waves and causing sound to be concentrated in certain areas rather than evenly distributed throughout the space. This can result in uneven sound quality and reduced clarity. In contrast, rooms with irregular shapes and non-parallel walls help to scatter sound waves, promoting better diffusion and a more balanced acoustic environment.

In designing a music room, carpet is the preferred flooring surface. This is because carpet helps to absorb sound, reducing echo and improving acoustics in the room. Additionally, carpet provides a softer and more comfortable surface for musicians and performers, allowing them to move and stand for longer periods without discomfort. Carpet also helps to insulate the room, providing warmth and reducing noise transfer to other areas of the building. Overall, carpet is the most suitable flooring option for a music room due to its sound-absorbing properties and comfort.

Panels of wood, glass, gypsum board, and plaster on lath are known to absorb low frequency sounds effectively. However, they do not provide much absorption at high frequencies. Therefore, the statement that these panels absorb low frequency sounds well but have little absorption at high frequencies is true.

A dead room is a room with a lot of soft furniture, heavy carpeting, and drapes that absorb sound, resulting in very little reverberation or echo. The peaks and valleys of the frequency response typically vary by 5-10 dB, indicating a relatively flat sound response without excessive resonance or reflections. This type of room is often used for recording studios or environments where a controlled and neutral sound is desired.

A live room is a room with bare walls and floor, and the peaks and valleys vary 10-20 dB or more. In a live room, the sound reflects and reverberates off the hard surfaces, creating a lively and vibrant acoustic environment. This type of room is commonly used for recording music or other audio productions where a natural and spacious sound is desired.

Frequency refers to the number of occurrences of a repeating event per unit time. In the context of the given question, frequency is the most appropriate term as it accurately describes the concept of the number of occurrences of a repeating event per unit time. Sound cycle, wavelength, and echo are not suitable answers as they do not specifically pertain to the concept of frequency.

The correct answer is velocity. Velocity refers to the speed of an object in a given direction. In the context of sound, the velocity of sound refers to how fast it travels through a medium, such as air or water. The speed of sound varies depending on the medium it travels through, with sound generally traveling faster in solids and liquids compared to gases. Therefore, velocity is the most appropriate term to describe the speed of sound.

Rubber, cork, and glass fiber pad are commonly used as vibration isolators. These materials have properties that allow them to absorb and dampen vibrations, reducing the transmission of vibrations from one object to another. Rubber is particularly effective due to its flexibility and ability to deform under load, while cork and glass fiber pads provide additional insulation and cushioning. Using all of these materials together can provide a comprehensive solution for isolating vibrations in various applications.

Gypsum is the best acoustical material used for a ceiling. Gypsum has excellent sound absorption properties, which helps in reducing noise levels and improving the overall acoustics of a room. It is a porous material that effectively absorbs sound waves, preventing them from bouncing off the ceiling and creating echoes. Gypsum also has fire-resistant properties, making it a safe choice for ceilings. Additionally, gypsum boards are easy to install and can be shaped into various designs, providing flexibility in ceiling aesthetics.

The correct answer is sabin. The unit of absorption is named after Wallace Clement Sabine, an American acoustician who made significant contributions to the study of architectural acoustics. The sabin is a unit used to measure sound absorption in a given space or material.

This statement suggests that surfaces that are more reflective tend to have a greater ability to scatter or spread sound in different directions, which is known as sound diffusion. This is because reflective surfaces bounce sound waves off them, causing them to disperse and fill the space more evenly. Therefore, the statement is true as it highlights the relationship between the reflectivity of a surface and the degree of sound diffusion.

A 12" double brick wall would provide the best sound insulation for a house fronting a busy highway. The thickness and density of the double brick wall would help to block out the noise from the highway, creating a quieter living environment inside the house. The double layer of bricks also adds an extra barrier for sound transmission, making it more effective in reducing noise compared to the other options listed.

Heavy weight elements transmit little sound and are more reflective. This is because heavy materials tend to be denser and have a higher mass, which allows them to absorb and dampen sound waves more effectively. On the other hand, light weight elements are less dense and have a lower mass, making them less effective at blocking sound and more prone to transmitting it. Additionally, heavy materials are more reflective because they have a greater ability to bounce back sound waves, whereas lighter materials tend to absorb and scatter sound.

Rubber seals, neoprene seals, and weather strips are all used to seal the gaps at the bottom edge of the door in order to prevent sound leak in public corridors. These materials are effective in blocking out noise as they provide a tight seal and minimize the gaps that allow sound to intrude. Therefore, all of the above options are correct solutions for sealing the gaps and reducing noise transmission in public corridors.

Reverberation refers to the persistence of sound after the source of sound has stopped. It is the result of multiple reflections of sound waves bouncing off surfaces in an enclosed space. These reflections create a series of echoes that blend together and continue to be heard even after the original sound has ceased. Reverberation can affect the quality and clarity of sound in a room or space, and is commonly experienced in concert halls, theaters, and other large enclosed areas.

Acoustical treatment refers to the application of materials or techniques that are specifically designed to absorb sound. This can include the use of sound-absorbing panels, diffusers, or other treatments that help reduce the reflection and reverberation of sound waves in a space. While soundproofing and noise control also involve managing sound, acoustical treatment specifically focuses on addressing sound absorption. Therefore, the given answer of acoustical treatment is correct as it aligns with the implication of sound absorptive treatment.

The unit of loudness level is called a phon. A phon is a unit of subjective loudness level that is based on the perception of sound by the human ear. It is used to measure the intensity or loudness of a sound as perceived by an average listener. The other options given, such as volume, amplitude, and loud, are not specific units of loudness level and do not accurately describe the measurement of sound intensity.

Loudness is the attribute of auditory sensation that allows sounds to be ordered on a scale from quiet to "LOUD". It refers to the perceived intensity or strength of a sound. Volume is also a measure of sound intensity, but it is more commonly used in the context of audio equipment or systems. Resonance refers to the vibration or amplification of sound waves in a particular object or space. Amplitude, on the other hand, is a measure of the maximum displacement of a sound wave from its equilibrium position.

The ratio of frequency to sound is 1:2. This means that for every 1 unit increase in frequency, there is a corresponding 2 unit increase in sound. In other words, as the frequency of a sound wave increases, the perceived sound also increases at a faster rate.

Convex reflective surfaces increase diffusion by scattering sound waves in different directions. This is because the curved shape of a convex surface causes sound waves to bounce off at various angles, preventing them from reflecting back in a focused manner. As a result, the sound is scattered and spread out, leading to increased diffusion.

Poured concrete walls are a good sound barrier for noise because they are dense and solid, which helps to block sound waves from passing through. The thickness of 150 mm adds to the effectiveness of the barrier by providing more mass for sound absorption. Drywall, while commonly used in construction, is not as effective at blocking sound as poured concrete. CHB walls, whether 8" or 6" thick, may provide some level of sound insulation, but they are not as effective as poured concrete due to their composition and density.

Open-celled materials have interconnected pores that allow sound waves to enter and get trapped within the material. This trapped sound energy is then converted into heat through friction, reducing the amount of sound reflected back into the environment. Therefore, open-celled materials are effective at absorbing sound, making the statement true.

Heavy curtains are the most effective material against ECHO because they are thick and dense, which helps to absorb sound waves and prevent them from bouncing back into the room. The heavyweight of the curtains also contributes to their effectiveness in reducing echo by dampening sound vibrations. Additionally, the fabric of heavy curtains has a soft texture that further helps to absorb sound, making them a suitable choice for minimizing echo in a space.

An octave is the interval between one musical pitch and another with half or double its frequency. This means that when two notes are one octave apart, the higher note has a frequency that is either double or half the frequency of the lower note. This concept is fundamental in music theory and is used to create harmony and melody.

The correct answer is decibel. Decibel is the unit of sound intensity. It is a logarithmic unit used to measure the intensity of sound. It is named after Alexander Graham Bell, who is the inventor of the telephone. The decibel scale allows us to quantify and compare the loudness of different sounds.

When a diver jumps into the water from a height, the direction of their movement changes due to the change in medium. This change in direction is caused by refraction, which is the bending of light or sound waves as they pass from one medium to another with different densities. In this case, the sound waves produced by the diver's jump strokes will also experience refraction as they travel from the air to the water, resulting in a change in their direction. Therefore, the correct answer is refraction.

Pilasters, piers, balconies ornamentation, and exposed beams are examples of architectural elements that can help to diffuse sound. Sound diffusers are designed to scatter sound waves in different directions, reducing echo and creating a more balanced acoustic environment. They are commonly used in spaces such as concert halls, theaters, and recording studios to improve sound quality. Sound absorbers, on the other hand, are materials that absorb sound waves, while soundproofing refers to the process of reducing or blocking the transmission of sound. Reflective elements of sound typically refer to surfaces that reflect sound waves, such as mirrors or smooth walls.

Resonance refers to the phenomenon when an object or system vibrates at its natural frequency due to the influence of an external force. In this context, a driving force that is in tune with the natural frequency will cause resonance to occur. This means that the external force is applied at the same frequency as the object's natural frequency, resulting in a large amplitude of vibration. Therefore, the correct answer is resonance.

To prevent an echo, the path length of difference between the direct sound and the reflected sound to a listener should not exceed 20 meters. This means that if the path length between the direct sound source and the listener is more than 20 meters, the reflected sound will reach the listener with a noticeable delay, causing an echo effect. By keeping the path length within 20 meters, the direct and reflected sounds will arrive at the listener's ears at almost the same time, minimizing the possibility of echo.

The term "pure" in this context refers to a sound that is free from any additional frequencies or harmonics. It suggests that the tone being described has a sinusoidal waveform, meaning it has a smooth, consistent oscillation without any distortion or irregularities. This type of waveform is often associated with a single frequency, hence the mention of "one energy, one frequency." Therefore, the correct answer is "pure."

The correct answer is amplitude. Amplitude refers to the maximum displacement of a particle from its equilibrium position in a sound wave. It determines the loudness or softness of a sound. A higher amplitude corresponds to a louder sound, while a lower amplitude corresponds to a softer sound. Sound intensity, on the other hand, refers to the amount of energy carried by a sound wave per unit area and is measured in watts per square meter. Noise is a general term used to describe any unwanted or unpleasant sound.

The 8" chb wall is the least effective in preventing sound from transmitting to the other side of the room because chb stands for concrete hollow blocks, which are not as dense as concrete or brick. The hollow spaces within the blocks allow sound waves to easily pass through, resulting in less sound insulation compared to the other options.

The statement is false because amplitude is actually a measure of the maximum displacement of particles in a medium caused by a sound wave. It is not directly related to the loudness of the sound pressure. Loudness, on the other hand, is determined by the intensity of the sound wave, which is related to the amplitude but also depends on other factors such as distance from the source.

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