FLOOR SOUNDPROOFING
Soundproofing floors is a process that requires a careful evaluation of the current construction and conditions; then the selection of a floor underlayment product that will actually work given your specific requirements. There is not a "cookie cutter" product that will work for all floors, or even 25% of the floors to be treated.
We consider it our responsibility to make sure you understand how products will work in your project. Products for concrete buildings don't always work for wood buildings; and there are even buildings where both are present! Your experience with Sound Isolation Company should be one where you are provided with relevant information that you can use to make an informed decision, even if our products are not appropriate for your job.
As we have done with every solution we offer, we do not settle for average results. We are only interested in products that will produce remarkable soundproofing for your floor. To further explain our approach and experience with floor soundproofing we offer an education section for soundproofing floors.
What is the difference in STC and IIC, and how are they tested?
Understanding how floors transmit noise, and the connection with the ceiling below.
This product says STC 71 and IIC 71, and it's only $ .20 a sqft!
How can I improve my existing floor without tearing everything up?
What is the difference in IIC and
STC, and how are they measured?
IIC is the measurement of sound energy blocked by a particular product when used on a tested floor/ceiling assembly. In this case the product is actually tested on a sub floor with an actual floor covering installed. A tapping machine is used to generate a constant impact and sound level on the floor, then the sound energy is measure below. The difference is the Impact Isolation Classification assigned to the material, when tested under that particular floor covering. The most accurate tests show a Delta (?¢À܂Ć) IIC; the additional IIC value that will be provided when the underlayment and finished floor are installed on the specific" floor/ceiling design tested. Remember, most of these test are done on very thick concrete, and that evaluation will not translate in wood construction.
STC is a measurement of the reduction in sound energy that a particular product will provide. How much noise will it block? Noise is generated at one end of a very long tube, the product is inserted and the sound levels on the other end are measured. The difference is the Sound Transmission Classification, in decibels, of that product. STC testing in multi level buildings is done to measure the difference in noise energy from one side of the floor to the other. It is very important to get the information in a table format that shows the reading at different frequencies. This STC value is only valuable in the comparison of products, and even then it doesn't mean a higher rated product will work better in your project.
The specific floor/ceiling can vary from one test to another, and this can dramatically affect outcome of the test. Some are done with a ceiling below; some are done without a ceiling at all. Others may have a ceiling with added isolation channels, insulation, etc. As a purchaser it becomes very hard to decide what will happen in your project; we are here to help.
- How will it work in a floor/ceiling assembly? Or better yet in your floor/ceiling.
- When this product is used, what is the performance at the frequencies that matter in your project?
More important are these two factors;
Understanding how floors transmit noise,
and the connection with the ceiling below.
When we discuss floor underlayments the elimination of footstep noise is usually the prominent goal. Floors transmit footstep noise in the form of vibration; a shoe impacts the hard floor, creates a vibration at the point of contact and that vibration (noise energy) is radiated outward through rigid connections. The transmission of footstep noise travels through many paths, an example is shown below;
With the many paths shown in the example above, you now have a complete picture of the challenges we face when assisting you to make a decision about floor underlayments. Because the ceiling below should be considered in your decision; the existing structure in your project has to be defined before the right product can be selected.
This product says STC 71 and IIC 71, and it's only $.20 a sqft!
As mentioned in the preceding section on IIC and STC testing, your project may be much different than the tested floor/ceiling.
This inflated data is commonly shown on literature, websites and in showrooms with no clarification. In our industry this is the most common misconception made by the consumer, and leads to much lower than expected results. Please carefully evaluate your current situation, and select a product that is appropriate. See if you can actually get a copy of the test that was done, including a description of the complete floor/ceiling construction tested.
Warning; The vast majority of IIC testing is done on 6" or more of concrete. Floor underlayment companies test their products for large commercial or multi-family projects, and want to get the highest IIC and STC for their product possible. Performance tested on a 6" concrete slab will never, ever happen if your building is a wood framed floor/ceiling.
We can provide unbiased information to help with your selection; we carry a wide variety of products, and have no particular loyalty to one or the other.
There are reputable companies that have tested their products in both concrete and wood frame conditions, and do state those values clearly. We may be the ones to explain that the $.20/sqft product you are looking at will not work; and that you may need to spend 5x as much for a product that's appropriate. We would rather lose the sale and provide you with relevant information than to disappoint you when the product is installed. Just don't shoot the messenger!
How can I improve my floor without tearing everything up?
You do have some options to improve your current floor; particularly if you have a floated floor or carpet. Typical projects include a 2nd or 3rd floor Home Theater/Media Room, basement location of the same thing, mother-in-law suite, basement remodel, etc. In many cases the STC (sound blocking) component and the IIC component are both a concern. There are solutions available for one, but maybe not for both issues. Again, your evaluation should be done carefully before selecting a product.
Given careful consideration these privacy between floors applications can be solved with one product. If the floor covering can be removed, we can install an appropriate product below. At that time we can also take some steps to address squeaking, popping and movement of the sub floor. Finally, the original floor covering can be installed and reused.
Find your Floor Soundproofing Product
Now that you know a little more about soundproofing your floor, make sure you take a look at the full line of quality floor soundproofing products we offer for floated/glued wood floor, nailed wood floors, carpet floors and tile & stone floors.
USING ELECTRICAL OUTLET EXTENSIONS
There are a few things you should know about using electrical outlet extensions.
Outlet Options
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Adjustable Zip Boxes
These boxes offer the same durability as our original line of Zip Boxes, with a twist - a single adjustment screw that adjusts the depth of the box to fit any situation.
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Handy Box Extension
Utility box extension with six 1/2" knockouts (sides). Two 1/2" knockouts (ends). This Handy Box Extension is one of many top quality items in our Box Extensions department.
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Square Extension Ring
Square extension ring with eight 1/2" & four 3/4" conduit knockouts sides. This Square Extension Ring is one of many top quality items in our Box Extensions department.
HARD CEILINGS
A sheetrock or wood ceiling gives us the best chance at a remarkable outcome. The heavier the ceiling the better we are able to stop noise. To effectively create a quiet ceiling, there are some questions that need to be answered.
Our first step is to clearly establish your goals for the ceiling soundproofing project. We need to know what the noise source is and where it is coming from; are you affected by footstep noise from above or just voices/tv/stereo? When we have the above information, we can move to the solution phase.
Good Ceiling Soundproofing Performance
Green Glue InstallationMany times we can leave your existing drywall ceiling in place, and use Green Glue to complete the project. Green Glue will provide measurable improvement for both footstep noise and airborne noise. Green Glue is the only product that was designed specifically for use over existing ceilings.
Better Ceiling Soundproofing Performance
When you are willing to remove the old ceiling, or are starting from scratch, we have the opportunity to create a mechanical separation from up to down. Using QuietClips, with a standard 7/8" hat channel, you will be able to attach new sheetrock to a floated metal channel rather than the bottom of the floor joist. Common sense tells us this is the best possible situation; vibration from footsteps and noise above cannot travel through the structure in either direction. One or two layers of sheetrock can be installed with our clips; you do not have to add any extra clips with 2 layers.
Best Ceiling Soundproofing Performance
As a second step, we have the ability to take your performance to the Luxury Level. Using one tube of Green Glue per 32 sqft, between two layers of sheetrock will add measurable results to the clip system above; two tubes will max out the available STC and IIC ratings.
LUXURY SOUND RATINGS
One of the most comprehensive guidelines established can be obtained from the U.S. Department of Housing and Urban Development in the Guide to Airborne, Impact, and Structure Borne Noise Control in Multifamily Dwellings.
Descriptive definitions of three grades of acoustic environments are given in order to ascribe criteria suitable to the wide range of urban developments, geographic locations, economic conditions and other factors involved in the areas of concern of the FHA. Constructions meeting the criteria will provide good sound insulation and satisfy most of the occupants in buildings fitting the conditions of each grade.
GRADE I - LUXURY RATING
Grade I is applicable primarily in suburban and peripheral suburban residential areas, which might be considered as the "quiet" locations and as such the nighttime exterior noise levels might be about 35-40 dB(A) or lower, as measured using the "A" weighting network of sound level meter which meets the current standards. The recommended permissible interior noise environment is characterized by noise criteria of NC 20-25 (32 dB(A)). In addition, the insulation criteria of this grade are applicable in certain special cases such as dwelling units above the eighth floor in highrise buildings and the better class or "luxury" buildings, regardless of location.
GRADE II - AVERAGE RATING
Grade II is the most important category and is applicable primarily in residential urban and suburban areas considered to have the "average" noise environment. The nighttime exterior noise levels might be about 40-45 dB(A); and the permissible interior noise environment should not exceed NC 25-30 (37dB(A)) characteristics.
GRADE III - MINIMUM RATING
Grade III criteria should be considered as minimal recommendations and are applicable in some urban areas which generally are considered as "noisy" locations. The nighttime exterior noise levels might be about 55 dB(A) or higher. It is recommended that the interior noise environment should not exceed the NC 35 (42 dB(A)) characteristic.
NOTES:
1. The most desirable plan would have the floor-ceiling assembly separating spaces with equivalent functions, e.g. living room above living room, etc.; however when this arrangement is not feasible the assembly must have greater acoustical insulating properties.
2. This arrangement requires greater impact sound insulation than the converse, where a sensitive area is above a less sensitive area.
3. Or dining, or family, or recreation room.
4. The airborne STC criteria in this table apply as well to vertical partitions between these two spaces.
5. This arrangement requires equivalent airborne sound insulation and perhaps less impact sound insulation than the converse.
MEASURING SOUND
Noise affects us everyday; at home, at leisure, during sleep, when traveling and at work. Taking an active role in making a room soundproof is not only soothing but could also yield noticeable health benefits. Below are a few things you should know about sound and how its measured.
What is STC?
STC stands for Sound Transmission Class. This is a method of gauging sound transmission loss through a wall. The American Standards and Testing Materials criteria is universally accepted by architects, designers, manufacturers, contractors and distributors of acoustical building products. The original acceptability of STC 34 walls must be reconsidered with the advent of increasing noise pollution.
STC Assessment:
Poor: 30 - 39
Good: 40 - 49
Better: 50 - 59
Excellent: 60 - 69
What are dBs?
While an STC rating is given in terms of points, the data is given in terms of decibels. A decibel, or dB, is a unit measure reflecting "how loud" a sound is. A sound pressure level of 0 dB represents the threshold of hearing in the most sensitive frequency range of a young, healthy ear, while the thresholds of tickling or painful sensations in the ear occur at about 120 to 130 dB.
Noise pollution:
In general, noise pollution refers to any noise irritating to one's ear which comes from an external source.
Sound Levels and Human Response
| Common Sound | Noise Level | Effect |
|---|---|---|
| Hearing begins | 0 dB | |
| 10 dB | Just Audible | |
| Broadcasting Studio | 20 dB | |
| Soft whisper | 30 dB | Very quiet |
| Quiet Office | 40 dB | |
| Light Auto Traffic | 50 dB | Quiet |
| Speech | 60 dB | |
| Noisy Restaurant | 70 dB | Intrusive |
| Alarm Clock | 80 dB | |
| City Traffic | 90 dB | Annoying |
| Garbage Truck | 100 dB | |
| Rock Concert | 110 dB | Very Loud |
| Jet Taking Off | 120 dB | |
| Thunderclap | 130 dB | Extremely Loud |
| Air Raid Siren | 140 dB | |
| Rocket Launching | 180 dB | Hearing loss |
Now that we understand roughly what sound is and how sound is measured let's identify the two main noise problem problems that people are dealing with. Read: Identify Your Noise Problem
ACOUSTIC GLOSSARY
In order to make your soundproofing experience more meaningful, the following glossary provides basic definitions of some of the industry's most common terms.
A | B | C | D | E | F | H | I | L | M | N | O | P | R | U | V | W
ABSORPTION: A property of materials that allows a reduction in the amount of sound energy reflected. The introduction of an absorbent material into the surfaces of a room will reduce the sound pressure level in that room by not reflecting all of the sound energy striking the room's surfaces. The effect of absorption merely reduces the resultant sound level in the room produced by energy that has already entered the room.
ABSORPTION COEFFICIENT: A measure of the sound-absorbing ability of a surface. It is defined as the fraction of incident sound energy absorbed or otherwise not reflected by a surface. Unless otherwise specified, a diffuse sound field is assumed. The values of the sound-absorption coefficient usually range from 0.01 for marble slate to almost 1.0 for long absorbing wedges often used in anechoic rooms.
ACOUSTICS: 1. The science of sound, including the generation, transmission, and effects of sound waves, both audible and inaudible. 2. The physical qualities of a room or other enclosure (such as size, shape, amount of noise) that determine the audibility and perception of speech and music within the room.
ACOUSTIC TRAUMA: Damage to the hearing mechanism caused by a sudden burst of intense noise, or by a blast. The term usually implies a single traumatic event.
AIRBORNE SOUND: Sound that reaches the point of interest by propagation through the air.
AMBIENT NOISE: The total of all noise in the environment, other than the noise from the source of interest. The term is used interchangeably with the term background noise.
ANECHOIC ROOM: A room in which the boundaries absorb nearly all the incident sound, thereby, effectively creating free field conditions.
ANSI: The American National Standards Institute.
ARTICULATION INDEX (AI): A numerically calculated measure of the intelligibility of transmitted or processed speech. It takes into account the limitations of the transmission path and the background noise. The articulation index can range in magnitude between 0 and 1.0. If the AI is less than 0.1, speech intelligibility is generally low. If it is above 0.6, speech intelligibility is generally high.
ATTENUATION: The reduction of sound intensity by various means (e.g., air, humidity, porous materials, etc).
AUDIO FREQUENCY: The frequency of oscillation of an audible sound wave. Any frequency between 20 and 20,000 hertz.
AUDIOGRAM: A graph showing individual hearing acuity.
AUDIOMETER: An instrument for measuring individual hearing activity.
A-WEIGHTED SOUND LEVEL: A measure of sound pressure level designed to reflect the acuity of the human ear, which does not respond equally to all frequencies. The ear is less efficient at low and high frequencies than at medium or speech-range frequencies. Therefore, to describe a sound containing a wide range of frenquencies in a manner representative of the ear's response, it is necessary to reduce the effects of the low and high frequencies with respect to the medium frequencies. The resultant sound level is said to be A-weighted, and the units are dBA. The A-weighted sound level.
BACKGROUND NOISE: The total of all noise in a system or situation, independent of the presence of the desired signal. In acoustical measurements, strictly speaking, the term "background noise" means electrical noise in the measurement system. However, in popular usage the term "background noise" is often used to mean the noise in the environment, other than the noise from the source of interest.
BAND: Any segment of the frequency spectrum.
BAND PASS FILTER: A wave filter that has a single transmission band extending from a lower cutoff frequency greater than zero to a finite upper cutoff frequency spectrum.
BROADBAND NOISE: Noise with components over a wide range of frequencies.
CALIBRATIOR (ACOUSTICAL): A device that produces a known sound pressure on the microphone of a sound level measurement system, and is used to adjust the system to Standard specifications.
COCHLEA: A spirally coiled organ located within the inner ear that contains the receptor organs essential to hearing.
CUTOFF FREQUENCIES: The frequencies that mark the ends of a band, or the points at which the characteristic of a filter change from pass to no-pass.
CYCLE: The complete sequence of values of a periodic quantity that occurs during one period.
CYCLES PER SECOND: A measure of frequency numerically equivalent to hertz.
CYLINDRICAL WAVE: A wave in which the surfaces of the constant phase are coaxial cylinders. A line of closely spaced sound sources radiating into an open space produces a free sound field of cylindrical waves.
DAMPING: The dissipation of energy with time or distance. The term is generally applied to attenuation of sound in a structure owing to the internal sound-dissipative properties of the structure or to the addition of sound-dissipative materials.
dBA: Unit of sound level. The weighted sound pressure level by the use of the A metering characteristics and weighted specified in ANSI Specifications for Sound Level Meters. dBA is used as a measure of human response to sound.
DECIBEL: A unit of sound pressure level, abbreviated dB.
DIFFRACTION: A modification which sound waves undergo in passing by the edges of solid bodies.
DIRECTIVITY INDEX: A measure of the angular direction of the sound radiation from the noise source presented as a dB level either higher or lower than that which would be radiated by a spherical sound source.
DOPPLER EFFECT (DOPPLER SHIFT): The apparent upward shift in frequency of a sound as a noise source approaches the listener or the apparent downward shift when the noise source recedes. The classic example is the change in pitch of a railroad whistle as the locomotive approaches and passes by.
DOSIMETER: A device worn by a worker for determining the worker's accumulated noise exposure with regard to level and time according to a pre-determined integration formula.
ECHO: A wave that has been reflected or otherwise returned with sufficient magnitude and delay, so as to be detected as a wave distinct from that directly transmitted.
EQUIVALENT A-WEIGHTED SOUND LEVEL (Leq): The constant sound level that, in a given time period, would convey the same sound energy as the actual time-varying A-weighted sound level.
FAR FIELD: Describes a sound source region in the free space where the sound pressure level obeys the inverse-square law (the sound pressure level decreases 6 dB with each doubling of distance from the source). Also, in this region the sound particle velocity is in phase with the sound pressure. Closer to the source where these two conditions do not hold constitutes the 'near field" region.
FILTER: A device for separating components of a signal on the basis of their frequency. It allows components in one or more frequency bands to pass relatively unattenuated, and it attenuates components in other frequency bands.
FREE SOUND FIELD (FREE FIELD): A sound field in which the effects of obstacles or boundaries on the sound propagated in that field is negligible.
FREQUENCY: The number of times per second that the sine wave of the sound repeats itself, or that the sine wave of vibrating object repeats itself. Now expressed in hertz (Hz), formerly in cycles per second (cps).
HAIR CELL: Sensory cells in the cochlea that transforms the mechanical energy of sound into nerve impulses.
HARMONIC: A sinusoidal (pure-tone) component whose frequency is a whole-number multiple of the fundamental frequency of the wave. If a component has a frequency twice that of the fundamental it is called the second harmonic, etc...
HEARING: The subjective human response to sound.
HEARING LEVEL: A measured threshold of hearing at a specified frequency, expressed in decibels relative to specified standard of normal hearing. The deviation in decibels of an individual's threshold from the zero reference of the audiometer.
HEARING LOSS: A term denoting an impairment of auditory acuity. The amount of hearing impairment, in decibels, measured as a set of hearing threshold levels at specified frequencies. Types of hearing loss are 1. Conductive: A loss originating in the conductive mechanism of the ear; 2. Sensor-neural: 3 A loss originating in the cochlea or the fibers of the auditory nerve; 3. Noise induced: A sensor-neural loss attributed to the effects of noise.
HEARING THRESHOLD LEVEL (HTL): Amount (in decibels) by which an individual's threshold of audibility differs from a standard audiometric threshold.
HERTZ (Hz): Unit of measurement of frequency, numerically equal to cycles per second.
IMPACT INSULATION CLASS (IIC): A single-figure rating that compares the impact sound insulating capabilities of floor-ceiling assemblies to a reference contour.
IMPACT SOUND: The sound produced by the collision of two solid objects. Typical sources are footsteps, dropped objects, etc. on an interior surface (wall, floor, ceiling) of a building.
IMPULSIVE NOISE: A) Either a single sound pressure peak (with either a rise time less than 200 milliseconds or total duration less than 200 milliseconds) or multiple sound pressure peaks (with either rise time less than 200 milliseconds or total duration less than 200 milliseconds) spaced at least by 200 millisecond pauses, B) A sharp sound pressure peak occurring in a short interval of time.
INFRASONIC: Sounds of a frequency lower than 20 hertz.
INTENSITY: The sound energy flow through a unit area in a unit of time.
INVERSE SQUARE LAW: A description of the acoustic wave behavior in which the mean-square pressure varies inversely with the square of the distance from the source. The behavior occurs in free field situations, where the sound pressure level decreases 6 dB with each doubling of distance from the source.
ISO: The International Organization for Standardization.
LEVEL: The logarithm of the ratio of a quantity to a reference quantity of the same kind. The base of the logarithm, the reference quantity, and the kind of level must be specified.
LOGARITHM: The exponent that indicates the power to which a number must be raised to produce a given number. For example, for the base 10 logarithm, used in acoustics, 2 is the logarithm of 100.
LOUDNESS: The subjective judgment of intensity of a sound by humans. Loudness depends upon the sound pressure and frequency of the stimulus. Over much of the frequency range it takes about a threefold increase in sound pressure (a tenfold increase in acoustical energy, or, 10 dB) to produce a doubling of loudness.
LOUDNESS LEVEL: Measured in phons it is numerically equal to the median sound pressure level (dB) of a free progressive 1000 Hz wave presented to listeners facing the source, which in a number of trials is judged by the listeners to be equally loud.
MASKING: 1. The process by which the threshold of audibility for a sound is raised by the presence of another (masking) sound. 2. The amount by which the threshold of audibility of a sound is raised by the presence of another (masking) sound.
MASKING NOISE: A noise that is intense enough to render inaudible or unintelligible another sound that is also present.
MEDIUM: A substance carrying a sound wave.
NEAR FIELD: The sound field very near to the source, where the sound pressure does not obey the inverse-square law and the particle velocity is not in phase with the sound pressure.
NIOSH: The National Institute for Occupational Safety and Health.
NOISE: 1. Unwanted sound. 2. Any sound not occurring in the natural environment, such as sounds emanating from aircraft, highways, industrial, commercial and residential sources. 3. An erratic, intermittent, or statistically random oscillation.
NOISE ISOLATION CLASS: (NIC) A single number rating derived in a prescribed manner from the measured values of noise reduction between two areas or rooms. It provides an evaluation of the sound isolation between two enclosed spaces that are acoustically connected by one or more paths.
NOISE LEVEL: For airborne sound, unless specified to the contrary, it is the A-weighted sound level.
NON-IMPULSIVE NOISE: All noise not include in the definition of impulsive noise.
NOISE REDUCTION (NR): The numerical difference, in decibels, of the average sound pressure levels in two areas or rooms after treatment. A measurement of "noise reduction" combines the effect of the sound transmission loss performance of structures separating the two areas or rooms, plus the effect of acoustic absorption present in the receiving room.
NOISE REDUCTION COEFFICIENT (NRC): A measure of the acoustical absorption performance of a material, calculated by averaging its sound absorption coefficients at 250, 500, 1000 and 2000 Hz, expressed to the nearest multiple of 0.05.
OCTAVE: The interval between two sounds having a frequency ration of two. There are 8 octaves on the keyboard of a standard piano.
OCTAVE BAND: A segment of the frequency spectrum separated by an octave.
OCTAVE BAND LEVEL: The integrated sound pressure level of only those sine-wave components in a specified octave band.
OSCILLATION: The variation with the time, alternately increasing and decreasing, of (a) some feature of an audible sound, such as the sound pressure, or (b) some feature of a vibrating solid object, such as the displacement of its surface.
OSHA: The Occupational Safety and Health Administration.
PEAK SOUND PRESSURE: The maximum absolute value of the instantaneous sound pressure in a specific time interval. Note: in case of a periodic wave, if the time interval considered is a complete period, the peak sound pressure becomes identical with the maximum sound pressure.
PERIOD: The duration of time it takes for a periodic wave form (like a sine wave) to repeat itself.
PERMANENT THRESHOLD SHIFT (PTS): A permanent decrease of the acuity of the ear at a specified frequency as compared to a previously established reference level. The amount of permanent threshold shift is customarily expressed in decibels.
PHON: The unit of measurement for loudness level.
PINK NOISE: Noise with constant energy per octave band width.
PITCH: The attributes of auditory sensation that orders sounds on a scale extending from low to high. Pitch depends primarily upon the frequency of the sound stimulus, but it also depends upon the sound pressure and waveform of the stimulus.
PLANE WAVE: A wave whose wave fronts are parallel and perpendicular to the direction in which the wave is traveling.
PRESBYCUSIS: The decline in hearing acuity that is attributed to the aging process.
PURE TONE: A sound for which the sound pressure is a simple sinusoidal function of the time, and characterized by its singleness of pitch.
RANDOM NOISE: An oscillation whose instantaneous magnitude is not specified for any given instant of time. It can be described statistically by probability distribution functions giving the traction of the total time that the magnitude of the noise lies within a specified range.
REFLECTION: The return of a sound wave from a surface.
REFRACTION: The bending of a sound wave from its original path, either because it is passing from one medium to another or by changes in the physical properties of the medium, e.g. a temperature or wind gradient in the air.
RESONANCE: The relatively large amplitude of vibration produced when the frequency of some source of sound or vibration "matches" the natural frequency of vibration of some object, component, or system.
RESONATOR: A device that resounds or vibrates in sympathy with a source of sound or vibration.
REVERBERANT FIELD: The region in a room where the reflected sound dominates, as opposed to the region close to the noise source where the direct sound dominates.
REVERBERATION: The persistence of sound in an enclosed space, as a result of multiple reflections, after the sound source has stopped.
REVERBERATION ROOM: A room having a long reverberation time, especially designed to make the sound field inside it as diffuse (homogeneous) as possible.
REVERBERATION TIME (RT): The reverberation time of a room is the time taken for the sound pressure level to decrease 60 dB from its steady-state value when the source of sound energy, is suddenly interrupted. It is a measure of the persistence of an impulsive sound in a room as well as of the amount of acoustical absorption present inside the room. Rooms with long reverberation times are called live rooms.
RMS SOUND PRESSURE: The square root of the time-averaged square of the sound pressure.
ROOT-MEAN SQUARE (RMS): 1. The root-mean-square value of a time-varying quantity is obtained by squaring the function at each instant, obtaining the average of the squared values over the interval of interest, and then taking the square root of this average. For a sine wave, if you multiply the RMS value by the square root of 2, or about 1.41, you get the peak value of the wave. The RMS value, also called the effective value of the sound pressure, is the best measure of ordinary continuous sound, but the peak value is necessary for assessment of impulsive noises. 2. A term describing the mathematical process of determining an 'average' value of a complex signal.
SABIN: A measure of the sound absorption of a surface; it is the equivalent of one square foot of a perfectly absorptive surface.
SHIELDING: The attenuation of a sound, achieved by placing barriers between a sound source and the receiver.
SONE: The unit of measurement for loudness. One sone is the loudness of a sound whose loudness level is 40 phons. Loudness is proportional to the sound's loudness rating, e.g. two sones are twice as loud as one sone.
SOCIOCUSIS: Loss of hearing caused by noise exposures that are part of the social environment, exclusive of occupational-noise exposure, physiological changes with age, and disease.
SOUND: 1. An oscillation in pressure, stress, particle displacement, particle velocity, etc. in an elastic or partially elastic medium, or the superposition of such propagated alterations. 2. An auditory sensation evoked by the oscillation described above. Not all sound waves can evoke an auditory sensation; e.g. ultrasound.
SOUND LEVEL: The weighted sound pressure level obtained by the use of a sound level meter and frequency weighting network, such as A, B, or C as specified in ANSI specifications for sound level meters (ANSI SI.4-1971, or the latest revision). If the frequency weighting employed is not indicated, the A-weighted is implied.
SOUND LEVEL METER: An instrument comprised of a microphone, amplifier, output meter, and frequency weighting networks which is used for the measurement of noise and sound levels.
SOUND POWER: The total sound energy radiated by a source per unit time. The unit of measurement is the watt.
SOUND PRESSURE: The instantaneous difference between the actual pressure produced by a sound wave and the average or barometric pressure at a given point in space.
SOUND PRESSURE LEVEL (SPL): 20 times the logarithm, to the base 10, of the ratio of the pressure of the sound measure to the reference pressure, which is 20 micronewtons per square meter. In equation form, sound pressure level in units of decibels is expressed as SPL (dB)=20 log p/p.
SOUND TRANSMISSION CLASS (STC): The preferred single figure rating system designed to give an estimate of the sound isolation properties of a structure or a rank order series of structures.
SOUND TRANSMISSION COEFFICIENT (STC): The average amount of decibels of sound reflected away from a partition by a particular reflective barrier material.
SOUND TRANSMISSION LOSS (STL): A measure of sound insulation provided by a structural configuration. Expressed in decibels, it is 10 times the logarithm to the base 10 of the reciprocal of the sound transmission coefficient of the configuration.
SPECTRUM: The description of a sound wave's resolution into its components of frequency and amplitude.
SPEECH-INTERFERENCE LEVEL (SIL): A calculated quantity providing a guide to the interference of a noise with the reception of speech. The speech-interference level is the arithmetic average of the octave band levels of the interfering noise in the most important part of the speech frequency range. The levels in the octave bands centered at 500, 1000 and 2000 Hz are commonly averaged to determine the speech-interference level.
SPEED (VELOCITY) OF SOUND IN AIR: 344 m/sec (128 ft/sec) at 70 degrees Fahrenheit in air at seal level.
SPHERICAL DIVERGENCE: The condition of propagation of spherical waves relates to the regular decrease in intensity of a spherical sound wave at progressively greater distances from the source. Under this condition the sound pressure level decreases 6 decibels with each doubling of distance from source.
SPHERICAL WAVE: A sound wave in which the surfaces of constant phase are concentric spheres. A small (point) source radiating into an open space produces a free sound field of spherical waves.
STEADY-STATE SOUNDS: Sounds whose average characteristics remain relatively constant in time. A practical example of a steady-state sound source is an air conditioning unit.
TEMPORARY THRESHOLD SHIFT (TTS): A temporary threshold impairment of hearing acuity as indicated by a change in the threshold of audibility.
THIRD-OCTAVE BAND: A frequency band whose cutoff frequencies have a ratio of 2 to the one-third power, which is approximately 1.26. The cutoff frequencies of 891 Hz and 1112 Hz define the 1000 Hz third-octave band in common use.
THRESHOLD OF AUDIBILITY (THRESHOLD OF DETECTABILITY): The minimum sound pressure level at which a person can hear a specified frequency of sound over a specified number of trials.
THRESHOLD OF PAIN: The minimum sound pressure level of a sound outside the ear that will produce a transition from discomfort to definite pain.
THRESHOLD SHIFT: A change in the threshold audibility at a specified frequency from a threshold previously established. The amount of threshold shift is customarily expressed in decibels.
TIMBRE: An attribute of auditory sensation allowing a subject to judge that two sound similarly presented and having the same loudness and pitch are dissimilar, e.g. trumpet vs. violin.
TINNITUS: Ringing in the ears or noise sensed in the head. Onset may be due to an acoustic trauma and persist in the absence of acoustical stimulation (in which case it may indicate a lesion of the auditory system).
TRANSDUCER: A device capable of being actuated by waves from one or more transmission systems or media and supplying related waves to one or more other transmission systems or media. Examples are microphones, accelerometers, and loudspeakers.
ULTASONIC: Sounds or frequency higher than 20,000 hertz.
VIBRATION: An oscillatory motion of solid bodies described by displacement, velocity, or acceleration with respect to a given reference point.
VIBRATION ISOLATOR: A resilient support for vibrating equipment designed to reduce the amount of vibration transmitted to the other structures.
WAVE: A disturbance that travels through a medium by virtue of the elastic properties of that medium.
WAVELENGTH: For a periodic wave (such as a sound in air), the distance between analogous points on any two successive waves. The wavelength of sound in air or in water is inversely proportional to the frequency of the sound. Thus, the lower the frequency, the longer the wavelength.
WEIGHTING: Prescribed frequency filtering provided in a sound level meter.
WHITE NOISE: Noise with energy is uniform over wide range of frequencies, being analogous in spectrum characteristics to white light.
WINDSCREEN: A porous device used to cover the microphone of a sound level measurement system that is designed to minimize the effects of winds and wind gusts on the sound levels being measured. Typically made of open cell polyurethane foam and spherically shaped.
TIPS AND TRICKS
It is Sound Isolation Company's goal to ensure your investment is a wise and effective one. Consider the following comments before choosing the soundproofing product for your project.
- We do not recommend buying soundproof foam as insulation between the floor joist and/or studs. By insulating between the studs or joist you are not breaking the path of noise vibration, the most important concern when soundproofing. It is expensive when compared to standard insulation and is not heavy enough to block noise, especially when compared to our soundproof barrier @ 1 lb/square foot.
- We do not recommend buying barrier with adhesive on it. The barrier will have to be secured with mechanical fasteners because the adhesive will not support it. Most importantly, soundproof barrier is meant to be flexible, not installed between layers of drywall. It works better when it is the first thing attached to the framing.
- We do not recommend using vibration mounts under a sheetrock wall. Sound isolation clips do not work if they are not "loaded". They must be supporting the wall or ceiling to effectively dissipate noise energy.
- We do not recommend buying supposedly "quiet" sheetrock. We regularly get calls from people who have purchased those products and are dissatisfied with the actual results. We have used these "high tech" products and found them to be marginally effective over existing wall and ceiling structures.
Furthermore, any claim of STC 52 wall is just an "average" soundproof wall, only 2 dB over the minimum requirement of STC 50 in most cases. If you want real peace and quiet, we do not suggest an STC of 52. Finally, the real cost for just one side of a wall is more than $4.00 a square foot, and if you review the actual lab testing, both metal tape, and acoustical caulk must be used at every joint, top, and bottom of every panel.
We have products that will perform equally for $ 1.50/sqft, and even better for a maximum of $ 3.00/sqft. - Our soundproof barriers are in stock every day. When comparing products make sure you understand that the weight of products is the key element. Be wary of samples that are not labeled.
The finished product and actual performance of the wall/ceiling/floor is what matters. We know what works because we have the experience to back it up.
BEST SOUNDPROOFING
After discussing Good and Better Soundproofing, it should be no surprise that the Best Soundproofing solution combines both decoupling, damping and materials of different densities. We have already shown that these three components are the foundation for predictable, proven results; we will now show that when combined they can deliver truly remarkable results.
You can actually save money over conventional methods used to obtain STC values in excess of 55. Rather than two sets of studs, or room within a room construction, simply use our proven products, in single stud framing.
Where "the best" Home Theater, Multi-Family Walls, or Commercial walls between tenants are required, the "old school" methods are based on multiple studs, wider more expensive base plates and headers, and "packing it full of insulation". While these methods can produce better than average results, they fail at the critical frequencies, take up usable space, and add to the cost of the project.
Our challenge is to obtain better walls, that will produce not only higher STC values, but more importantly with be more effective at the most critical frequency ranges. The use of single studs, regular fiberglass, and truly effective soundproofing products will create walls that are much quieter in the real world; cost less, and save space.
By using both Sound Isolation Clips and Green Glue you will be using two proven technologies; sound isolation by decoupling, and sound damping which converts vibration energy into low grade heat. This particular combination will eliminate the need for double stud or staggered stud wall construction. The sound reduction across all frequency bands is remarkable with this proven system. The tested value of the assemblies below will support the previous statements.
Where additional space to construct a better wall is the biggest challenge, we have some solutions that will minimize the build up, and provide very good results.
STC isn't everything! One of the challenges we face as a company is the re-education of our customers regarding the effectiveness of a soundproofing system rather than the STC value alone. A high STC value does not necessarily mean you will actually get high sound blocking for your application.
BETTER SOUNDPROOFING
While our discussion of Good Soundproofing pointed out that much better than minimum walls are available with simple improvements to standard construction, you might think that "better" soundproofing required a much more complicated process; that is not the case at all!
Again we are able to provide better results than staggered stud, and sometimes better than double wall construction, at a lower cost, and save usable space. Our "better" soundproofing will provide Luxury Sound Ratings between living spaces, and the required sound blocking for your Home Theater Walls, Home Studio Walls, or Band Rehearsal Walls.
Better Soundproofing is available with one very important principle added to your wall construction; the elimination of mechanical connection between one side and the other. We call this process decoupling, and you can achieve this with less than $ 1.00 per square foot (bottom of page) added to your construction cost.
All noise is actually vibration energy, this excites the particles in air and you "hear" the sounds with your eardrum. Sound Transmission, Footstep Noise, Traffic Noise or Neighbor Noise is all basically vibration energy. The lower the frequency, think bass drum, the more actual energy is present. Lower frequency noise is the hardest to block or absorb. In residential, commercial and mixed-use construction we simply cannot build a heavy enough wall to block the lowest frequencies. Additionally, low frequency noise is more likely to travel through the structure than high frequency noise, further complicating the process.
To effectively defeat low frequency noise, and the transmission of noise through the structure, we need to decouple one side of the wall, and by using QuietClips, we can do just that. Decoupling requires that we eliminate the 100's of connection points created by screws, nails, brackets, plates etc. We use clips and hat channel to float walls, the sheetrock is screwed to the channel, the channel is supported by the clip, and no screws pass through the channel- mechanical isolation for one side of the wall!
Adding Sound Isolation Clips to a basic single stud, insulated wall with STC 37-40 will raise the sound rating to a remarkable STC 57. Compare the added cost of soundproofing products in the shown assemblies above, and you will be able to make an educated decision when choosing your solution; you don't always get what you paid for!
| Wall Type | Construction | Depth | Extra Cost | STC | Benifits |
|---|---|---|---|---|---|
| Standard Wall Assembly | 5/8" Type X Drywall 2"x4" Wood Studs R-13 Fiberglass Insulation 5/8" Type X Drywall |
4.75" | $.00 per sq. ft. | 45-47 | |
| Quietclips Wall Assembly | 5/8" Type X Drywall 2"x4" Wood Studs R-13 Fiberglass Insulation Quietclips - 7/8" Hat Channel 5/8" Type X Drywall |
5.25" | $.99 per sq. ft. | 57 | |
| Double Stud Wall Assembly | 5/8" Type X Drywall 2"x4" Wood Studs R-13 Fiberglass Insulation 1" Airspace R-13 Fiberglass Insulation 2"x4" Wood Studs 5/8" Type X Drywall |
10.5" | $.90 per sq. ft. | 53 | |
| Quiet Sheetrock Wall Assembly | 5/8" Type X Drywall 2"x4" Wood Studs R-13 Fiberglass Insulation 5/8" Quiet Sheetrock Drywall |
4.75" | $3.37 per sq. ft. | 56 |
There is even more performance available, see Best Soundproofing.
GOOD SOUNDPROOFING
At Sound Isolation Company we have very high standards for the sound blocking capability of a good wall. Our "good" is probably higher than any other company you will find. We don't accept minimum compliance with local building codes, you shouldn't either; with reliable, proven products you can obtain very good results, and stay within your budget.
For soundproof wall construction, we will refer to the Sound Transmission Classification (STC) as a measurement of the walls ability to block noise. A typical residential wall has an STC of 38-40, a normal commercial wall may have an STC 42-45. For a reference point that will make your choices simple, the minimum standard for a HUD financed public housing project requires an STC 45 between units.
For new construction you have a couple of easy steps to insure a good performing wall or ceiling assembly.
Step One:
Use fiberglass insulation in the cavity; thickness according to the depth of the cavity R-11 for 2x4 studs, R-19 for 2x6 studs. Using more expensive insulation will provide no measurable improvement in the STC rating.
Step Two:
Option 1: Use 2 tubes of Green Glue between 2 layers of sheetrock, on one side of wall. Green Glue is applied in a random pattern, on the second layer of sheetrock, and then everything is screwed together. Green Glue Installation
Option 2: Install our UL Rated Soundproof Barrier on one side of the wall, directly attached to studs, then install 5/8" sheetrock over the barrier. You must use Soundproof Barrier on the studs, before sheetrock is installed; the product is not intended to be used between sheetrock layers. Soundproof Barrier installation
Step Three
The details in constructing a "good" soundproof wall are very important. Every outlet box and switch box must be covered with a Seal Tight Putty Pad, There should be a small gap at the perimeter of the wall; this will be filled with Silenseal Acoustical Sealant
Soundproofing Tips
When we refer to sheetrock we are always assuming you will use 5/8" type X sheetrock. Heavier is always better, the small increase in price is negligible, and the benefits are measurable.
Staggering the sheetrock seams from one layer to the next is a very good idea. This helps overcome the shared seam as a leak in the wall system.
Make sure electrical boxes on opposite sides of the wall are not in the same stud cavity. Again, we don't want a "leak" in the system; don't assume that this will be done, bring it up to your contractor. Even better use our sound rated Sealtight Putty Pads for each electrical box.
Carefully consider the cost and the performance of other solutions when compared to our two options. Cost is not always an indication of the results, and you can't compare STC values in the low 40's to values of 47 or above.
There is still improvement available, build an even "better" soundproof wall; Better Soundproofing.
Fiberglass Insulation
Green Glue
UL Soundproof Barrier
Silenseal Acoustical Sealant
Sealtight Putty Pads
CONDUCTING A Q.U.I.E.T. AUDIT
To effectively and efficiently counsel you on the optimal solution to your noise problem, please consider conducting the following Q.U.I.E.T. audit on your project.
Quantify:
Consider the room or rooms you would like to add soundproofing to. Measure the length and height of the walls to be treated.
Understand:
Some projects may require the removal of the existing wall structure. An understanding of your comfort level with reconstruction will help us recommend a solution.
Itemize:
To provide the best solution, we need to understand what you have now. Determine if the wall has been insulated, measure the thickness of the sheetrock, plaster, paneling or other wall covering.
Expectations:
Set your aesthetic expectations. How important is the final appearance? Are you looking for a finished product to cover your wall or a more utilitarian solution?
Talk:
Our recommended course of action will be determined by the type of noise problem you face (airborne or structural) in combination with the answers to the Q.U.I.E.T audit.
Below are some standard assemblies used in residential and commercial spaces. Your specific needs and the results you require will determine what assembly is right for you.
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Good Soundproof Assembly: STC 51-54
A simple way of improving your walls, floors and ceilings assembly is adding Soundproof Barrier. By attaching Soundproof Barrier to your ceiling joist or wall stud and adding a layer of standard drywall, you will block up to 75% more noise than drywall alone. Read More
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Better Soundproof Assembly: STC 55-57
Adding a Green Glue between two layers of building materials (i.e. drywall, plywood, OSB) to your walls, ceilings and floors assembly will effectively reduce impact and airborne noises. Read More
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Best Soundproof Assembly: STC 60+
Combing soundproofing materials will result in better performance. Adding Soundproofing Barrier or Green Glue with Sound Isolation Clips is one of your best options. Read More
IDENTIFY YOUR NOISE PROBLEM
What is making that noise? Where is it coming from? Is the noise passing through the wall or vibrating through the wall? Once you have correctly diagnosed the noise source you can begin taking the proper steps to solve and isolate the problem.
Airborne Noise
Conversation, TV, radio and other noise that can actually pass through your wall is called airborne noise and is caused by walls that are too lightweight to sufficiently block the noise.
This is a common problem with modern construction as the codes have not evolved to meet the demands of today's normal occurrences. Often office, residential and multi-family walls are built with 1/2" sheetrock more because it meets minimum code than for peaceful living or work environment.
Structure Borne Noise
The low frequency noise caused by home theaters, stereos or music practice is called structure borne noise. This noise can actually pass through a well insulated wall in the form of vibration. This is the kind of noise you can actually feel in your feet or with your hands.
What will help stops noise?
Space: The more space, the more reduction in sound levels. Many have solved their soundproofing issues by building staggered stud walls, double stud walls or installing Sound Isolation Clips. All of these methods help decouple the wall and increase the sound isolation.
Mass: The heavier the wall, floor or ceiling assembly the better it will work at blocking sound.
Dampening: Like a wine glass when you make it ring...but you can keep it quiet by holding it. You have to dampened the noise by retarding the vibrations.
You can achieve remarkable results combining space, mass and damping in your projects. Next lets look at evaluating your project by Conducting a Quiet Audit and see what steps are need to solve your noise problem.
