Ch. 14 Acoustics

Question 1

What are the three basic qualities of Sound

Answer 1

Velocity frequency and power

Question 2

This quality of sound depends on the medium in which the sound is traveling in the temperature of the medium.

Answer 2

Velocity

Question 3

This quality of sound is the number of cycles composed per second and is measured in hertz one hertz equals one cycle per second

Answer 3

Frequency

Question 4

The quality of acoustic energy as measured in whites. This is what people perceive as loud Ness

Answer 4

Power

Question 5

What is the threshold of human hearing and the threshold of pain

Answer 5

0 dB and 130 dB

Question 6

What is the sound range of a healthy young person

Answer 6

It can range from 20 to 20,000 Hz and is most sensitive to frequencies in 3000 to 4000 Hz range

Question 7

What range of sounds is speech composed of

Answer 7

Speech is composed of sounds primarily in the range of 120 to 8000 Hz, with most in the range of 200 to 5000

Question 8

unwanted sound

Answer 8

Noise

Question 9

What are the two basic problems controlling noise

Answer 9

Preventing or minimizing the transmission of sound from one space to another and reducing the noise within a space

Question 10

What are the two important concepts in noise reduction

Answer 10

Transmission loss and noise reduction between two spaces

Question 11

Takes into account only the loss through the partition

Answer 11

Transmission loss

Question 12

This is dependent not only on the transmission laws but also on the area of the partition separating the two spaces in the absorption of the surface in the quiet room

Answer 12

Noise reduction

Question 13

How to noise reduction be Increased

Answer 13

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 some combination of all three

Question 14

The selection of wall construction in other building components, it’s single rating called what is often used to write the transmission loss of construction

Answer 14

Sound transmission class STC

Question 15

The higher the STC rating, the better the barrier is in what

Answer 15

Stopping sound

Question 16

This can be used to specify the maximum amount of continuous background noise allowable in a space, to establish a minimum amount of noise desired to help mask sounds, and to evaluate an existing condition

Answer 16

Noise criteria curve

Question 17

This is used to control unwanted sound reflection, improve speech privacy, and decrease or increase reverberation

Answer 17

Sound absorption 

Question 18

The ratio of sound intensity absorbed by the material to the total intensity reaching the material. The maximum therefore is one

Answer 18

The coefficient of absorption

Question 19

What material is considered to be reflective what is it coefficient

Answer 19

0.2 or below

Question 20

The average of the materials absorption coefficient see is at the four frequencies of 250, 500, 1000, and 2000 Hz, rounded to the nearest multiple of 0.05.

Answer 20

Noise reduction coefficient NRC

Question 21

What is the NRC been superseded by

Answer 21

That sound absorption average SAA

Question 22

The average of the absorption coefficients is for 12 1/3 octave bands from 200 Hz to 2500 Hz when tested in the same accordance with the a STMC423

Answer 22

S AA

Question 23

What are some of the rules and her designers can follow for noise reduction in critical situation

Answer 23

Avoid designing rooms with hard, reflective surfaces on the walls, floor, and ceiling. The space will be to live and noisy.

The average absorption go fission of a room should be at least 0.2. An average absorption above 0.5 is usually not desirable, nor is it economically justified. A lower value for suitable for large Rams well larger values are suitable for small or noisy rooms

Each doubling of the amount of absorption in a room results in a noise reduction of only 3 dB hardly noticeable. To make any difference the total absorption must be increased by at least three times to change the reduction by 5 dB which is actually noticeable

Although it’s sort of materials can we please anywhere, ceiling treatment for sound absorption is Matt more effective in large rooms, while while treatment is more effective in small rooms 

Question 24

What are the three primary ways sound can be controlled within a space

Answer 24

Reducing the level of loudness of the sound source, modifying the absorption in the space, introducing nonintrusive background sound to mask the unwanted sound

Question 25

Are used to purposely introduce carefully controlled sound into space rather than rely only on random background noise

Answer 25

White noise, random noise, or acoustic perfume

Question 26

what is one way to build a sound resistant partition

Answer 26

Add mass to the wall

Question 27

What is the second technique to build a sound resistant partition

Answer 27

A Play insulation within the stud cavity. This at the words sound and reduces energy that is transmitted through one layer of the wall before it reaches the other.

Question 28

What is the third way to build a sound resistant partition

Answer 28

Resilient channel can be used as furring strips on one side of the partition. Because of their design, only one leg of the channel touches the studs in the wall board floats and damp and sound striping it rather than transmitting it to the stud

Question 29

What are ways to deal with doors placed in otherwise well-built sound wall

Answer 29

The perimeter could be completely sealed with weatherstripping specifically designed to sound ceiling at the GM and head to the threshold or automatic door bottom at the sill.

Question 30

A piece of hardware that drops the seal from the door to the floor or threshold as the door closes. The door itself should be easy heavy as possible, preferably a solid forward door. Often, two doors are used, separated by small air gap

Answer 30

Automatic door bottom

Question 31

How is glass soundproof

Answer 31

Interior glass lights can be designed with laminated glass set an a resilient frame. Laminated glass provides more mass, and the plastic innermost layer improves the dampening characteristics of the barrier. If additional transmission loss is required, two or more layers can be installed with an air gap between them

Question 32

A condition in which talking may be hard as a general backgrounds down but not easily understood

Answer 32

Speech privacy

Question 33

The divider should have a combination of absorptive services to minimize sound reflections over a solid linear called a what

Answer 33

Septum

Question 34

Sound resulted in direct contact of an object with sound barrier, can occur on any surface, but it generally occurs on the floor and ceiling assembly. It is usually caused by foot fall, shuffle furniture, and dropped objects.

Answer 34

Impact noise

Question 35

Impact noise is quantified by this it is a number, a single number rating of a floor/ceilings impact sound performance. The higher the better the floor performs in reducing impact sounds

Answer 35

Impact insulation class i I c

Question 36

This is a single number rating of the average sound absorption of material over a limited frequency range, including 250 Hz, 500 Hz, 1000 hearts, and 2000 hearts, rounded to the nearest multiple of 0.05. These readings can range from zero to one. Acoustical ceiling tiles are generally in a range of 0.65 to 0.9. And open offices, values of 0.85 or higher are recommended

Answer 36

Noise reduction coefficient in RC

Question 37

This is also a single number rating, but the frequency range includes 500 Hz, 1000 Hz of a 2000 Hz, and 4000 hearts, this range more closely represents the frequencies of speech and may be a better rating to use in evaluating in selecting ceiling tiles

Answer 37

Speech range absorption SRA

Question 38

A single number measure of a transmission loss through ceiling tiles between two closed rooms where there’s no war other barrier above the suspended ceiling. It gives in a given in units of decibels and is similar to the STC values described in the previous section. Most acoustical ceiling tiles have a rating between 30 to 35 dB which is minimally effective at blocking sound.

Answer 38

Ceiling attenuation class CAC

Question 39

The two methods used to measure speech privacy and open offices

Answer 39

Articulation class and articulation index

Question 40

A single member summation of how effective is ceiling is in absorbing sound reaching out from overload partitions. The rating is a summation of waited sound attenuation is in 15 test in frequencies from 200 Hz to 5000 Hz, with higher waited factors in the frequencies representing most human speech. The test is used to determine this writing uses a 9 foot high ceiling and standard 60 inch high partitions

Answer 40

Articulation class AC

Question 41

Measures the performance of all elements of a particular configuration working together, including ceiling absorption, space to voters, furniture, light fixtures, partitions, background masking systems are white noise, HVAC system sound. Does predicts the intelligibility of speech for a group of talkers and listeners. The best results of the test is a single number writing, which is a range of zero to one with 0 being completely private and one thing absolutely no privacy.

Answer 41

Articulation index AI