Term
| Qualities of sound (3 basic qualities) |
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Definition
| Velocity, frequency, and power. Velocity depends on the medium in which the sound is traveling and the temperature of the medium. Frequency is the number of cycles completed per second and is measured in Hertz (Hz). One Hz equals one cycle per second. The sounds that we call high notes have higher frequencies, base notes have lower frequencies. |
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Term
| Power is the quality of acoustic energy as measured in...... |
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Definition
| Watts, it is this power that people percieve as loudness. |
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Term
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Definition
| relates actual sound intensity to the way humans experience sound. By definition zero decibel is the threshold of human hearing, and 130 decibels is the threshold of pain. |
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Term
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Definition
| an important variable in how a frequency is transmitted or absorbed, it must be taken into account in building acoustics. |
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Term
| Two basic problems in controlling noise |
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Definition
| preventing or minimizing the transmission of sound from one space to another and reducing the noise within a space. |
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Term
| The transmission of sound is.... |
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Definition
| primarily retarded by the mass of the partition. The stiffness, or rigidity, of the partition is also important. Given two partitions of the same weight per square foot, the one with less stiffness will perform better than the other. |
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Term
| Two important concepts in noise reduction: |
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Definition
| transmission loss and actual moice reduction between two spaces. Transmission loss takes into account only the loss through the partition. Noise reduction is dependent not only on the transmission loss byt also on the area of the partition separating the two spaces and the absorption of the surfaces in the "quiet" room. Noise reduction can be increased by increasing the transmission loss of the partition, by increasing the absorption in the "quiet" room, by decreasing the area of the common wall between the rooms, or by some combination of all three. |
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Term
| Sound Transmission Class (STC) |
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Definition
| a single number rating is often used to rate the transmission loss of construcion. The higher the STC rating, the better the barrier is in stopping sound |
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Term
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Definition
| such as cracks, electrical outlets, doors, will significantly lessen overall noise reduction. |
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Term
| The proper amount of sound absorption must.... |
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Definition
| be included to minimize noise within a space. Sound absorption also is used to control unwanted sound reflections (noise), to improve speech privacy, and the decrease or increase reverberation. |
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Term
| The absorption of a material is defined by.... |
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Definition
| the coefficient of absorption, a, which is the ratio of the sound intensity absorbed by the material to the total intensity reaching the material. |
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Term
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Definition
| Noise reduction coefficient - the average of a material's absorption coefficients at the four frequencies of 250, 500, 1000 and 2000 Hz, rounded to the nearest multiple of 0.05. |
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Term
| Noise Reduction within a space |
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Definition
| avoid designing rooms with hard, reflective surfaces on the walls, floor and ceiling. The average absorption above 0.50 is usually not desirable, nor is it economically justified. A lower value is suitable for large rooms, and largers values are suitable for smaller or noisy rooms. Each doubling of the amount of absorption in a room results in a noise reduction of only 3dB-hardly noticable. To make a difference, you must increase the total absorption by at least three times to change the reduction by 5dB, which is noticable. Ceiling treatment for sound, absorption is more effective in large rooms, while wall treatment is more effective in small rooms. |
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Term
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Definition
| is the prolongation of sound as it repeatedly bounces off hard surfaces. It is an important part of the acoustic environment of a space because it affects the intelligibility of speech and the quality of music. |
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Term
| Three primary ways sound can be controlled within a space: |
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Definition
| by reducing the level of loudness of the sound source, by modifying the absorption in the space, and by introducing nonintrusive background soudn to mask the unwanted sound. |
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Term
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Definition
| In an office, if the sound level on one side of a partition with an STC rating of 45 is 75dB and the background noise on the other side of the partition is 35dB, the noise coming through the partition will not be heard on the "quiet" side of the wall. If the background noise level is decreased to 25dB, then sounds will be heard. |
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Term
| White sound, random noise, or acoustic perfume |
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Definition
| controlled sound into a space rather than rely only on random background noise. |
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Term
| Control of sound transmission |
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Definition
| primarily dependent on the barriers mass and to a lesser extent on its stiffness. Walls and floors are generally rated with their STC value, the higher the STC rating, the better the barrier is at reducing transmitted sound. |
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Term
| Several methods used to build a sound resistant partition |
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Definition
| Add mass to a wall. Place insulation within the stud cavity. Resilent channels can be used as furring strips on one side of the partition. |
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Term
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Definition
| is regarded as a condition in which talking may be heard as a general background sound but not easily understood. Most often required in open office plans. |
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Term
| 5 important factors in designing for speech privacy in an open area |
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Definition
| 1. the ceiling must be highly absorptive. The ideal is to creat a "clear sky" condition so tha sounds are not reflected from their source to other parts of the space. 2. The area must include space dividers that reduce the transmission of sound from one space to the adjacent spaces. 3.Other surfaces, such as the floor, furniture, windows, and light fixtures, must be designed or arranged to minimize sound reflections. 4. If possible, activities should be distanced to take advantage of the normal attenuation of sound with distance. 5. the area should have a properly designed background masking system. If the right amount of sound-absorbing surfaces is provided, the masking system will absorb all sounds in the space, not just the unwanted sounds |
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Term
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Definition
| sound resulting from direct contact of an object with a sound barrier, can occur on any surface, but it generally occurs on a floor and ceiling assembly. quantified by the impact insulation class (IIC) number, a single number rating of a floor/ceilings impact sound performance. |
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Term
| Room geometry and planning concepts |
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Definition
| plan similar use areas next to each other. use buffer spaces such as closets and hallways to separate noise-producing spaces whenever possible. stagger doorways in halls an other areas to avoid providing a straight-line path for noise. If possible, try to locate furniture and other potential noise producing objects away from the wall that is separating spaces. Minimize the ares of the common wall between two rooms where a reduction in sound transmission is desired. Avoid room shapes that reflect or focus sound, such as barrel vaulted hallways and circular rooms |
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Term
| 3 acoustic ratings of ceilings |
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Definition
| Noise reduction coefficient (NRC) and the Speech range absorption (SRA)single number rating, but the frequency range includes 500, 1000, 2000, 4000 Hertz, and Ceiling Attenuation Class (CAC)single number measure of the transmission loss through ceiling tiles between two closed rooms where there is no wlal or other barrier about the suspended ceiling |
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