Bu - Acoustics (Annayazu)

Break-out noise refers to the noise that escapes or breaks out from the interior of a duct and is heard on the exterior. This can occur when the duct system is not properly sealed or insulated, allowing sound waves to travel through the walls of the duct and into the surrounding environment. Break-out noise can be a nuisance for both the occupants of the building and those in the vicinity, and it is important to address it through proper duct design and insulation to minimize its impact.

The absorption coefficient refers to the fraction of sound energy that is absorbed by a surface. It is a measure of how well a material or surface absorbs sound waves. A higher absorption coefficient indicates that more sound energy is absorbed, while a lower coefficient indicates that more sound energy is reflected or transmitted. This coefficient is important in various applications, such as designing acoustic treatments in rooms or selecting materials for soundproofing.

Acoustics is the correct answer because it is the branch of science that specifically focuses on the production, control, transmission, reception, and effects of sound in an enclosed space. Acoustics studies how sound waves behave in different environments, such as rooms or concert halls, and how they can be manipulated for various purposes like improving sound quality or reducing noise. It also examines the impact of sound on human perception and physiology. Therefore, Acoustics is the most appropriate term to describe the science described in the question.

Structure-borne sound refers to the transmission of sound waves through a solid structure. When sound waves encounter a solid object, such as a wall or a floor, they can travel through it and cause vibrations. These vibrations then propagate through the structure, producing sound on the other side. This type of sound transmission is different from air-borne sound, which travels through the air, and direct sound, which travels in a straight line from the source to the receiver. Intermittent sound refers to sound that occurs at irregular intervals.

Break-in noise refers to the noise that enters the interior of a duct system from the surrounding environment. This can occur when there are gaps or openings in the ductwork, allowing external noise to penetrate into the ducts. The noise can come from various sources such as traffic, machinery, or other external activities. It is important to minimize break-in noise to ensure a quieter and more comfortable indoor environment.

Scattering refers to the phenomenon where sound waves are irregularly deflected or dispersed in different directions when they encounter an obstacle or an irregular surface. This can occur when sound waves interact with objects or surfaces that have dimensions similar to the wavelength of the sound. As a result of scattering, sound is distributed in various directions, leading to a loss of sound intensity and a diffusion of the sound energy. Therefore, scattering is the most suitable explanation for the irregular diffraction of sound in many directions.

A live room is a room that has minimal sound absorption, meaning that sound waves are able to bounce off the surfaces and create a lively and reverberant sound. This is often desirable in recording studios or concert halls where a natural and spacious sound is desired. In contrast, a dead room would have a high amount of sound absorption, resulting in a very dry and controlled sound. A white room and black room do not provide any information about the sound absorption properties of the room.

Intermittent sound refers to sounds that occur at irregular intervals or are not continuous. This can include sounds that fluctuate in volume or have breaks in between. Unlike direct sound, which travels in a straight line from the source to the receiver, or indirect sound, which is reflected off surfaces, intermittent sound does not follow a consistent pattern. Focusing sound, on the other hand, refers to the manipulation of sound waves to concentrate them in a specific direction, and is not related to the discontinuity or fluctuation of the sound itself.

Air-borne sound refers to sound waves that are transmitted through the air. When an object vibrates, it creates sound waves that travel through the air and reach our ears. This is the most common type of sound that we encounter in our daily lives, such as the sound of music, voices, or any other sound that we hear in the environment. Therefore, air-borne sound is the correct answer as it accurately describes the sound caused by vibrations that transmit through the air.

A small opening in a barrier that allows air-borne sound to pass through it is called a leak. A leak refers to a gap or hole in a surface or structure that allows the passage of air or sound. It can be found in various contexts, such as in pipes, roofs, or walls, where it can cause unwanted airflow or sound transmission.

Sound is the correct answer because the given explanation describes the response of the human ear to pressure fluctuations in the air caused by vibrating objects. This response is perceived by humans as sound. The explanation also mentions that sound travels in space by a phenomenon called "wave motion," further reinforcing that sound is the correct answer.

Frequency refers to the number of cycles per second in a wave or oscillation. It is measured in units of "cps" or "Hz" (Hertz). This term is commonly used in various fields such as physics, electronics, and telecommunications to describe the rate at which a wave repeats its pattern. The higher the frequency, the more cycles occur in a given time period, resulting in a shorter wavelength. Therefore, frequency is the correct answer in this context.

The surfaces of the front portion of an auditorium should be highly reflective in order to enhance sound projection and clarity. Reflective surfaces help to bounce sound waves off the walls, allowing them to reach the audience with minimal loss of energy. This ensures that the sound is clear and audible throughout the auditorium, providing a better listening experience for the audience.

Boomy refers to a condition of sound where the male voice range is excessively reverberant. This means that the sound produced by a male voice is characterized by a deep, resonant, and booming quality. It can be caused by factors such as the acoustic properties of the room or the microphone used.

White noise is a type of noise that has equal energy at all frequencies within a given range. It is called "white" because it is analogous to white light, which contains all colors of light in equal amounts. In the context of sound, white noise sounds hissy because it consists of random sound waves at different frequencies, creating a "hissing" or "shushing" sound. It is often used in audio engineering, sleep therapy, and sound masking applications. Ambient noise refers to the background noise present in a particular environment, while break-in noise and black noise are not commonly recognized terms in relation to sound.

The reflection coefficient is a measure of the sound reflective property of a surface. It indicates the amount of sound that is reflected back from the surface compared to the incident sound. A higher reflection coefficient indicates a more reflective surface, while a lower reflection coefficient indicates a more absorptive surface.

The correct answer is "Prolonged reverberation." When there are large amounts of reflective surfaces in a space, sound waves bounce off these surfaces multiple times before dissipating, resulting in a prolonged reverberation time. This means that the sound lingers in the space for a longer duration, creating a longer decay time and a more pronounced echo effect. Therefore, "prolonged reverberation" accurately describes the situation of long reverberation time caused by the presence of reflective surfaces.

Infrasonics refers to frequencies below the range of human hearing, which is typically less than 20 Hz. Ultrasonics, on the other hand, refers to frequencies above the range of human hearing. Microsonic and macrosonic are not commonly used terms in the field of sound frequency. Therefore, the correct answer is Infrasonics.

The distance between two adjacent compressions or rarefactions in a sound wave is referred to as the wavelength. Wavelength is a fundamental property of a wave and is defined as the distance between two corresponding points on a wave, such as two adjacent compressions or rarefactions in the case of a sound wave. It is measured in meters and is inversely related to the frequency of the wave. Higher frequency waves have shorter wavelengths, while lower frequency waves have longer wavelengths.

The measurement of the number of cycles in one second in a sound wave is referred to as Hertz (Hz). Hertz is the unit of frequency and represents the number of cycles or vibrations per second. In the context of sound waves, the frequency determines the pitch of the sound. Higher frequency waves have a higher pitch, while lower frequency waves have a lower pitch. Therefore, Hertz is the appropriate measurement for quantifying the frequency or pitch of a sound wave.

The correct answer is "Pitch". Pitch refers to the perceived frequency of a sound wave, specifically in the context of a pure tone. It is a subjective perception that allows us to distinguish between high and low frequencies. Purity, on the other hand, refers to the absence of any additional frequencies or overtones in a sound. Creep is unrelated to the perception of frequency, and tinnitus is a medical condition characterized by hearing ringing or buzzing sounds in the ears.

An echo is a distinct reflection of the original sound that occurs when the path of the reflected sound is significantly longer than the path of the direct sound. This results in a delay between the original sound and its reflection, creating a repetition or reverberation effect. The phenomenon of an echo is commonly observed in large open spaces or in the outdoors where sound waves can bounce off surfaces such as walls, mountains, or buildings, and travel back to the listener.

Ultrasonic refers to frequencies that are above the range of human hearing, which is typically considered to be between 20 Hz and 20,000 Hz. Ultrasonic frequencies are commonly used in various applications such as medical imaging, cleaning, and pest control. They are also utilized by animals like bats and dolphins for echolocation. Therefore, the given correct answer, "Ultrasonic," accurately describes the frequency range above human hearing.

The correct answer is Sabin. Sabin is a unit used to measure sound absorption. It represents the amount of sound absorbed by a material or surface. It is named after Wallace Clement Sabine, who was a pioneer in the field of architectural acoustics. The Sabin value of a material or surface depends on its size, shape, and composition. A higher Sabin value indicates better sound absorption, while a lower value indicates poor sound absorption.

Tinnitus refers to the perception of noise or ringing in the ears. It is a condition where a person hears sounds that are not present in the external environment. This can be a continuous or intermittent sound and can vary in pitch and intensity. Tinnitus can be caused by various factors such as exposure to loud noise, ear infections, certain medications, and underlying health conditions. It is often associated with hearing loss and can significantly impact a person's quality of life.

Fidelity refers to the faithfulness or accuracy with which a sound surface is reproduced. It implies that the reproduction is true to the original and does not introduce any distortions or alterations. In the context of sound, fidelity is often used to describe the quality of audio reproduction systems, such as speakers or headphones, that can accurately reproduce the original sound without any loss of clarity or detail. Therefore, fidelity is the most appropriate term to describe a faithful reproduction of a sound surface.

When two objects collide, they produce a sound that is commonly referred to as impact noise. This noise occurs due to the forceful collision and the resulting vibrations and energy transfer between the objects. The term "impact" accurately describes the nature of the noise, as it is caused by the impact or collision of the two objects.

A dead room is a room that has a high level of sound absorption. This means that sound waves are absorbed rather than being reflected or reverberated. This can be achieved through the use of materials such as foam panels or acoustic tiles on the walls, floor, and ceiling. The purpose of a dead room is to minimize echo and reverberation, creating a very quiet and controlled environment for recording or scientific experiments where precise sound measurements are required.

The Noise Reduction Coefficient (NRC) is a single number rating that is derived from the values of sound absorption coefficient. It is used to measure the effectiveness of a material or surface in reducing the amount of sound energy reflected back into a space. A higher NRC value indicates better sound absorption properties, meaning that the material or surface is more effective in reducing noise levels in a room.

The surfaces of the rear portion of an auditorium should be highly absorptive to minimize sound reflections and reverberations. This helps to improve the acoustics of the space by reducing echo and ensuring that the sound reaches the audience clearly and intelligibly. Highly absorptive surfaces absorb sound energy rather than reflecting it back into the space, resulting in better sound quality and clarity for the audience.

Diffraction is the correct answer because it refers to the change in direction of propagation of sound caused by bending of a barrier. When sound waves encounter an obstacle, such as a barrier, they can bend around it and spread out into the region behind the barrier. This bending and spreading out of sound waves is known as diffraction. Reflection refers to the bouncing back of sound waves when they encounter a surface, resonance refers to the reinforcement of sound waves due to matching frequencies, and attenuation refers to the decrease in the intensity of sound waves as they travel through a medium.

Attenuation refers to the reduction in sound level as it travels through a medium. It occurs due to various factors such as absorption, scattering, and reflection. Unlike diffraction, which is the bending of sound waves around obstacles, attenuation specifically focuses on the decrease in sound intensity. Reverberation, on the other hand, refers to the persistence of sound due to multiple reflections in an enclosed space. Resonance is the phenomenon where an object vibrates at its natural frequency when exposed to an external force. Therefore, attenuation is the most appropriate term to describe the reduction in sound level.

A diffuse sound field refers to a sound field where the sound comes in equal intensity from all directions. In this type of sound field, the sound waves are scattered and reflected in various directions, creating a sense of spaciousness and envelopment. This is often achieved by using diffusive surfaces or by placing multiple sound sources strategically in a room. Unlike a reflective sound field where the sound is primarily reflected off hard surfaces or an absorptive sound field where the sound is absorbed by materials, a diffuse sound field ensures a more balanced and even distribution of sound throughout the space.

Isolation refers to the lack of acoustical connection between two spaces or objects. It is the process of separating or blocking sound waves from one area to another, preventing the transmission of sound. In the context of the given options, isolation is the most suitable choice as it directly relates to the concept of a lack of acoustical connection. Reverberation refers to the persistence of sound in a space, attenuation refers to the reduction in sound intensity, and loudness refers to the subjective perception of sound intensity.

Decay refers to the gradual decrease in the loudness of the reverberation or sound. As sound waves bounce off surfaces, they lose energy and eventually fade away. This process is known as decay. It is a natural phenomenon that occurs in various acoustic environments, such as concert halls or empty rooms. The answer "Decay" accurately describes the concept of the dying out of sound and the steady decline in loudness of the reverberation.

The correct answer is Decibel (dB). The decibel is a unit used to measure the intensity or power of sound. It is a logarithmic scale that compares the sound pressure level, sound intensity level, or sound power level to a reference level. The decibel scale allows for the representation of a wide range of sound levels, from the faintest to the loudest sounds. It is commonly used in fields such as acoustics, audio engineering, and noise measurement to quantify and compare sound levels.

Environmental noise refers to the background noise present in a specific environment, such as a neighborhood. This noise can come from various sources like traffic, aircraft, construction, or other outdoor activities. It is called environmental noise because it is a part of the overall environment and can have an impact on the quality of life for individuals living in that area.

The transmission coefficient refers to the ratio of transmitted sound energy to incident sound energy. It measures the effectiveness of a material or medium in allowing sound to pass through it. A high transmission coefficient indicates that a large amount of sound energy is able to pass through the material, while a low transmission coefficient suggests that the material is effective in blocking or attenuating sound.

Reverberation refers to the persistence of sound in an enclosed space after the initial source has been eliminated. This phenomenon occurs due to multiple reflections of sound waves off the surfaces of the room. These reflections create a complex pattern of overlapping sound waves, resulting in a prolonged decay of sound. Reverberation can affect the clarity and quality of sound in a space, and is commonly experienced in concert halls, auditoriums, and other large enclosed areas.

A flutter echo is a rapid succession of sound caused by highly reflective parallel surfaces. This phenomenon occurs when sound waves bounce back and forth between two parallel surfaces, creating a series of repeated echoes. Unlike a regular echo, which is a single reflection of sound, a flutter echo is characterized by a rapid repetition of echoes, giving it a distinct fluttering or vibrating sound. This can be commonly heard in spaces with parallel walls, such as stairwells or empty rooms, where the sound waves bounce back and forth multiple times before dissipating.

Background noise refers to the continuous or steady sounds present in a particular environment. It can include various sounds such as the hum of appliances, the buzzing of fluorescent lights, or the distant traffic noise. This type of noise is typically present in everyday situations and can be considered as the normal or expected level of noise in a given setting. It is often referred to as background noise because it is constantly present and serves as a backdrop to other sounds in the environment.

The correct answer is Sound transmission class (STC). STC is a single number rating that measures the sound insulation performance of a partition. It represents the ability of a partition to reduce sound transmission from one side to the other. A higher STC rating indicates better sound insulation. OITC measures the sound transmission between outdoor and indoor spaces, NIC measures the sound isolation between adjacent spaces, and NRC measures the sound absorption capabilities of materials. However, none of these ratings specifically measure the sound insulation performance of a partition like STC does.

Loudness is the correct answer because it refers to the auditory sensation that is influenced by both sound pressure level and sound frequency. It is a measure of the perceived strength or volume of a sound, with higher sound pressure levels and frequencies typically resulting in a greater perception of loudness. Pitch, intensity, and isolation are not directly related to the combination of sound pressure level and sound frequency, making them incorrect choices.

An anechoic chamber is a sealed room where all surfaces are designed to absorb sound completely. This means that any sound produced inside the room will be absorbed and not reflected back, creating an environment with no echo or reverberation. This is achieved through the use of materials with high sound absorption properties, such as foam or fiberglass. Anechoic chambers are commonly used for acoustic testing and research purposes, as they provide a controlled environment with minimal sound interference.

Resonance occurs when the frequency of an external force matches the natural frequency of an object, resulting in a large amplitude of vibration. In this case, when the frequency is equal, it causes a large amplitude of vibration, indicating resonance. Scattering refers to the redirection of waves in different directions, attenuation refers to the decrease in the intensity of waves as they propagate, and reverberation refers to the persistence of sound due to multiple reflections.

The correct answer is Outdoor-Indoor transmission class (OITC). OITC is a single number rating that measures the sound reduction effectiveness of a partition that separates the exterior from the interior. It takes into account the transmission loss of sound through the partition at different frequencies and provides a comprehensive evaluation of the partition's ability to reduce sound transmission from outdoor to indoor spaces. STC, on the other hand, is a similar rating but specifically measures the sound reduction effectiveness of a partition that separates two interior spaces. IOTC and Exterior-Interior transmission class are not recognized terms in the field of acoustics.

The correct answer is sound pressure. Sound pressure refers to the variation in air pressure caused by the fluctuating pressure of sound waves superimposed on the static air pressure. It is a measure of the force exerted by sound waves on a surface and is commonly used to quantify the loudness or intensity of sound.

Undue focusing of sound is the correct answer because when sound waves encounter concave surfaces, they converge at certain points in a room. This concentration of sound energy at specific points leads to an excessive focusing of sound, causing an imbalance in the distribution of sound energy throughout the room. As a result, other parts of the room experience a loss of sound energy, leading to an uneven and distorted sound experience known as undue focusing of sound.

Transmission loss (TL) is the measure of sound insulation of a partition. It quantifies the reduction in sound energy as it passes through a partition, such as a wall or door. TL is expressed in decibels (dB) and represents the difference in sound intensity between the source side and the receiving side of the partition. A higher TL value indicates better sound insulation, as it means less sound is transmitted through the partition. TL takes into account both the transmission and absorption of sound, making it a comprehensive measure of the partition's sound insulation capabilities.

Sound intensity level (SIL) is the correct answer because it is a quantity expressed in decibels of air-borne sound. Decibels are used to measure the intensity or loudness of sound, and sound intensity level specifically refers to the level of sound intensity measured in decibels. This measurement is commonly used in various fields to quantify and compare the loudness of different sounds.