Information on the sound level (2023)

sound level specifications: THE EVOLUTION OF CALM

Por John C. Dolehanty

September 2005

Q.- What is the easiest and most economical way to guarantee the tranquility of industrial facilities?

A.- Sound Level Specifications.

Many companies have suffered through the frustrating cycle of spending valuable resources quieting their facilities, only to have their efforts frustrated by purchasing and installing noisy equipment and machinery. Smart companies learn from this experience and implement sound level specifications to ensure machines and equipment are designed and built to run quietly.

Proper use of a sound level specification when purchasing new equipment is essential to any noise control and hearing protection program. The sound level specification prevents noise problems in new installations and helps reduce noise levels in older installations over time as noisy equipment is replaced with quieter equipment.

The intent of this article is to (1) explain the purpose of a machinery sound level specification and why it is important, (2) highlight the components of an effective specification, and (3) identify common pitfalls when assessing compliance with the Specifications.

Purpose of a sound level specification

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An effective noise abatement program is highly dependent on a purchase specification for a working noise level. The primary purpose of a sound level purchase specification is to ensure that noise control measures are considered and implemented in the design and construction process. This ensures that the installed device meets your primary criteria of preventing/reducing employee participation in the Hearing Conservation Program (HCP). Criteria for secondary equipment may include meeting an environmental performance limit or meeting interior office limits that ensure adequate voice communications (office HVAC, etc.).

The primary purpose of the sound level specification is to help prevent noise-induced hearing loss by ensuring that employee noise exposure does not exceed 85 dBA TWA.8 standard. Noise exposure of a full shift (8 hour) employee of 85 dBA TWA8 hoursrequires employers to establish and maintain an ongoing and effective hearing protection program.

With a sound level purchase specification in place, future sound mitigation efforts are generally limited to keeping the equipment and controls currently in place. Without a specification to purchase a working sound level, current and past noise abatement efforts can be thwarted when noise-producing equipment is in close proximity to areas/workers that have been silenced due to abatement efforts. noise.

OSHA does not require noise levels for equipment. If you purchase a device that causes employee exposure levels to exceed 85 dBA TWA, you haveAlsotook responsibility for maintaining an ongoing and effective hearing protection program!

The scheduled replacement of noisy equipment is the ideal opportunity to reduce noise levels. Time and resources are available for this. It is important that a sound level specification be part of the replacement process.

Use hearing conservation programs

An average sound level limit of 80 dBA is intended to prevent hearing loss related to work related noise. A sound level purchase specification that refers to an A-weighted sound pressure level at 1 meter cannot address environmental noise (perimeter/community noise) issues, nor is it appropriate to address indoor acoustics and floor intelligibility issues. speaks.

In the case of environmental concerns, reference should be made to the local noise protection ordinance. Property limits for industrial sources typically range from 55 dBA to 70 dBA. Interior acoustics are generally treated using NC and RC curve criteria. For example, open plan offices are often designed to be NC-40 compliant.

Essential components of effective sound level specifications

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Factors such as regulatory limits, additional effects of additional noise sources, operator intervention, types of equipment, and available control technology are important to consider when selecting a specification noise level limit.

Many sound level purchase specifications limit the sound pressure level of new equipment to an average sound level of 80 dBA (or less) at 1 meter across the equipment/system enclosure and at any position on the operator. This limit has proven to be very effective in preventing employee exposure from exceeding 85 dBA TWA. A limit of 80 dBA was chosen to allow the introduction of a sound level of 80 dBA in areas where the current sound level is 83 dBA and has not yet exceeded a cumulative sound level of 85 dBA. (A-weighted sound levels are provided because A-weighted levels are used to assess worker noise exposure.) It should also be noted that some specific pieces of equipment have traditionally been specified in terms of sound power levels, particularly electric motors. Note that the sound power level of an electric motor (LW) of 85 dBA is actually less than 80 dBA at 1 meter.


A Type I or II integrating sound level meter is the preferred instrument for determining the sound level of equipment. The sound level meter must be able to measure average, maximum, minimum and peak sound levels. A non-integrated sound level meter should only be used if the device in question produces a very constant (unchanging) sound level (this is rare!). The meter must be configured so that there is no lower limit threshold (to capture the full range of sound levels from the device). Also, a 3 dB slew rate (or doubling rate) is typically used. This setting more accurately reflects the actual physical level of sound propagation, in contrast to OSHA's more liberal 5 dB reference setting for worker exposure control.

An octave band (frequency) sound level meter is not usually needed, but it can be useful when measuring ultrasonic (radio frequency) sources.

measurement method

Most sound level purchase specifications are based on information from the National Machine Tool Builders Association (NMTBA).noise measurement techniques, Second Edition, January 1976. The NMTBA has been superseded by the Association for Manufacturing Technology (AMT) and they are in the final stages of approving an updated ANSI technical reference guide: B11.TR5:Sound Level Measurement Guidelines, a guide for measuring, evaluating and documenting sound levels emitted by machineryto replace the NMTBA guidance.

Generally average (Lequalizer) Sound levels are measured at a distance of 1 meter along the perimeter of the equipment/system along with all operator positions. The sound level meter should be placed 1.5 meters from the ground (according to the hearing range of an average person), unless there is a defined operator position at other heights.

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Sound level measurements should be made under typical operating conditions and should cover the worst operating conditions. Most devices experience this under load, but some systems actually generate higher noise levels when idle. Furthermore, the sound level must be averaged over several cycles of the device to ensure that the measured values ​​are representative.

The background noise level (during the test) should always be as low as possible, preferably 10 decibels or more below the specified limit. Background levels that are 10 decibels or more below the device level are acoustically insignificant. The background noise level should be measured prior to device testing and then subtracted from the device noise level.

Common Conformity Assessment Mistakes

Many companies feel that their sound level specification protects them from noisy equipment. Unfortunately, due to a lack of acoustic expertise and sometimes improper use of the device, it is not uncommon to find incorrectly documented sound level data. These mistakes and oversights can be costly to both vendors and end users of the equipment.


calibration- The measuring devices must be calibrated before and after the on-site measurement sessions (with a portable calibrator). If the meter does not calibrate within ±1 decibel after the measurement session, the meter measurements should be repeated. In addition, the measurement devices must be recalibrated annually in a certified testing laboratory. The integrating sound level meter and its associated field calibrator must always have a stamp indicating that their laboratory calibration can be traced back to the National Institute of Standards and Technology (NIST). Meter calibration documentation should always accompany any written report.

A common mistake is using the wrong gauges. Whenever possible, an integrating sound level meter should be used. A non-integrated sound level meter should only be used when sound levels are neither fluctuating nor stable.

Construction- The sound level meter must be correctly configured. Typically this would involve: setting the rate of change to 3dB, setting the threshold to 0dB (or the lowest possible setting), setting the dynamic range so that sound levels are essentially even between high and low levels, and set the measurement metric to Lequalizer(average level). Ideally, the meter should also simultaneously measure the following metrics: sample time, LMaximum, yoMinimum, me toosummit. A dosimeter is often used to document equipment sound levels. That in itself is not a problem.AndThe meter is set up correctly. Remember that the standard dosimeter setup is for documenting employee exposure.noEvaluation of the sound level of the devices.

Another common mistake is when the wrong device conditions are measured. Sound level measurements should be representative of typical (or, in some cases, worst case) production/operating conditions. If these conditions are not possible, a simulation/graph can be used. For example, multiple sources can be measured separately and then mathematically combined to get the total sound level. (Remember to remove the undertone from each individual source measurement.)

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It is worth noting that equipment measurements are very different from a measurement of employee noise exposure. The use of typical employee dosimeter equipment/techniques may result in incorrect information. Typical employee exposure measurements (OSHA) use a lower limit threshold of 80 dBA with an exchange rate of 5 dB. An 80 dBA threshold setting integrates all sound levels below 80 dBA as 0 dBA in this setting. This incorrect setting usually results in artificially low sound levels.


A common measurement error occurs when the meter is placed too close to the device in the belief that this will provide a good sample (such as an air sample). Since sound pressure is a function of distance from the sound source, the location of the meter is critical.

The background level should be subtracted from the measured device sound level. Optimally, the background should be at least 10 dBA below the sound level of the device. The background noise level variability should be stable as the background noise level approaches the device noise level.

Perimeter sound levels should never be averaged; They should be treated as independent data points. And remember, decibels are logarithmic values ​​and cannot be manipulated using standard arithmetic means.

Key to successfully using the sound specification

The key to successfully using a sound level specification to minimize the deleterious effects of noise in an industrial facility is to create a partnership between the buyer and the supplier. Key elements of this partnership include:

  • Timed coordination- Addressing noise issues before equipment is placed in service leads to more effective noise abatement efforts.
  • Training- Does your company provide supplier training to help them understand your specification and perform conformance assessments?
  • documentation- Do you provide suppliers with guidelines and formats for documenting measurement locations, meter settings, duration of each sample, and calibration history?
  • Rating and comments- Assessing vendor capabilities and providing feedback on compliance efforts provides a foundation for improving both specification compliance and consistent data delivery.

Remember: A sound level purchase specification can only be effective if it is consistently applied and enforced. A good rule of thumb to remember: Equipment vendors' efforts to meet purchasing sound level specifications reflect the same commitment they make to enforcing them!

Mr. Dolehanty is president of Phase To, Inc. and has over 18 years of experience in the hearing protection and noise control fields. You can contact Mr. Dolehanty at (517) 886-9379 and

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What is the sound level? ›

Sound level refers to various logarithmic measurements of audible vibrations and may refer to: Sound exposure level, measure of the sound exposure of a sound relative to a reference value. Sound power level, measure of the rate at which sound energy is emitted, reflected, transmitted or received, per unit time.

Why is sound level important? ›

Experts say hearing damage can occur from any noise level higher than 85 decibels, which is comparable to heavy traffic. As the decibels increase, so does the risk of hearing loss.

How do I know my sound level? ›

Use a professional decibel meter.

Though it's not usually cheap, perhaps the most direct, accurate way to find the decibel level of a sound you with to analyze is to use a decibel meter.

What is a good sound level? ›

Sounds at or below 70 dB are considered safe for our hearing. That's the sound of a normal conversation between two people. Sounds at 80 or 85 dB will damage hearing over time.

What are the types of sound level? ›

Types. The IEC 61672-1 specifies "three kinds of sound measuring instruments". They are the "conventional" sound level meter, the integrating-averaging sound level meter, and the integrating sound level meter.

What affects sound level? ›

Loudness refers to how loud or soft a sound seems to a listener. The loudness of sound is determined, in turn, by the intensity, or amount of energy, in sound waves. The unit of intensity is the decibel (dB).

What is the most important use of sound? ›

Of these senses, hearing is one of the most fundamental and important to our accumulation of knowledge and our understanding of the world. Sound is vital to sharing information, interacting with other people, creating art, regulating schedules, and countless other aspects of life.

How does sound level affects the performance of a person? ›

In this study, we found that a sound level of 110 dB was an important contributor to individuals' performances, i.e., the individuals' performances were decreased. However, sound levels of 70 and 90 dB had no significant association with the both error rate and the length of performance.

What is a safe sound level? ›

Decibel Level​

Sounds at or below 70 dBA are generally considered safe. Any sound at or above 85 dBA is more likely to damage your hearing over time.

What is the difference between sound level and loudness? ›

The intensity of a sound is the power of the sound in Watts divided by the area the sound covers in square meters. The loudness of a sound relates the intensity of any given sound to the intensity at the threshold of hearing. It is measured in decibels (dB).

What is normal sound range? ›

Humans can detect sounds in a frequency range from about 20 Hz to 20 kHz. (Human infants can actually hear frequencies slightly higher than 20 kHz, but lose some high-frequency sensitivity as they mature; the upper limit in average adults is often closer to 15–17 kHz.)

What is the normal noise level in a room? ›

For example, people generally only feel comfortable with a noise level of 30 – 40dB in a bedroom but will happily work in an open plan office with a noise level of 45 – 50dB. You would expect a background noise in a library to be around 30dB.

What are the 3 types of sound? ›

Sound waves are characterized into three types. Audible sound waves are those that humans can hear. Infrasonic waves are those that are too low-frequency (below 20 Hz) for humans to hear. Ultrasonic sounds waves are those that are too high-frequency (above 20,000 Hz) for humans to hear.

What is another word for level of sound? ›

sound intensity; volume; sound level; noise level; sound volume; background level.

What are the two main types of sound? ›

Sound has two basic forms: acoustic energy and mechanical energy. Each type of sound has to be tackled in their own way. Acoustic energy or sound is what we experience every day. It is in fact vibration of air (sound waves) which is transformed by the tympanic membrane in the ear of human to audible sounds.

How are sound levels monitored? ›

HOW IS NOISE MEASURED? Basically, there are two different instruments to measure noise exposures: the sound level meter and the dosimeter. A sound level meter is a device that measures the intensity of sound at a given moment.

What is sound How does it work? ›

Sound is produced when an object vibrates, creating a pressure wave. This pressure wave causes particles in the surrounding medium (air, water, or solid) to have vibrational motion. As the particles vibrate, they move nearby particles, transmitting the sound further through the medium.

How do you normalize a sound level? ›

How to normalize volume level for a group of audio tracks?
  1. Introduction.
  2. Step 1: Download and install AVS Audio Editor.
  3. Step 2: Open audio files.
  4. Step 3: Select the Normalize effect and set its properties.
  5. Step 4: Make a list of files to be modified.
  6. Step 5: Save the resulting audio.

What makes sound high or low? ›

Pitch. The sound an object makes changes depending on how fast it is vibrating. When an object vibrates quickly, high-pitched sounds are heard. Low-pitched sounds come from things that vibrate more slowly.

What makes sounds louder or quieter? ›

Volume – louder and softer

Sound vibrations travel as waves. Like waves in water, the waves get smaller the further they travel (unless something acts to boost them), so the closer we are to the source of a sound, the louder it is.

What causes louder sound? ›

The size of the vibration (also called amplitude) determines the volume. The amplitude of the vibration carries the energy. A big vibration causes large sound waves that transmit a lot of energy. The resulting volume of sound is loud – for example, a balloon bursting or a dog barking.

What are 3 things about sound? ›

Here are some fun facts about sound to get you started!
  • Sound travels much slower than light, whether in the air or in water. ...
  • The sound of a baby's cry is very hard to ignore. ...
  • The fear of noise is called Acousticophobia and the fear of music is called Melophobia.
Jan 24, 2023

How do you describe a sound? ›

Sounds are often described as loud or soft; high-pitched or low-pitched. These words are commonly used to describe, or characterize, how sounds are perceived.

What three things do you need for sound? ›

Three components are needed for sound to be heard:
  • A source – where the sound is made.
  • A medium – something for the sound to travel through.
  • A receiver – something to detect the sound.
May 10, 2011

What level of sound can affect hearing? ›

Sound is measured in decibels (dB). A whisper is about 30 dB, normal conversation is about 60 dB, and a motorcycle engine running is about 95 dB. Noise above 70 dB over a prolonged period of time may start to damage your hearing. Loud noise above 120 dB can cause immediate harm to your ears.

How does the volume of the sound affect you? ›

The louder the sound -- the faster the damage to your hearing. As a benchmark, a normal conversation is about 60 decibels -- considered a safe level, not loud enough to cause damage. But increase it to 85 decibels, and that's about the volume of your vacuum cleaner.

How does sound affect your mood? ›

Research has long shown that sound rooted in major chords tends to produce positive emotions, and sounds rooted in minor chords produce negative emotions. On the other hand, sounds that we hear in everyday life often come to represent something to the listener, which affects the emotional response.

What is the sound level for OSHA? ›

OSHA sets legal limits on noise exposure in the workplace. These limits are based on a worker's time weighted average over an 8 hour day. With noise, OSHA's permissible exposure limit (PEL) is 90 dBA for all workers for an 8 hour day. The OSHA standard uses a 5 dBA exchange rate.

What is the average hearing range by age? ›

People of All ages without a hearing impairment should be able to hear the 8000hz. People under 50 should be able to hear the 12,000hz and people under 40, the 15,000hz. Under 30s should hear the 16,000hz, and the 17,000hz is receivable for those under 24. MORE: Test!

What can cause hearing loss? ›

Risk factors
  • Aging. Degeneration of inner ear structures occurs over time.
  • Loud noise. Exposure to loud sounds can damage the cells of your inner ear. ...
  • Heredity. ...
  • Occupational noises. ...
  • Recreational noises. ...
  • Some medications. ...
  • Some illnesses.
Apr 16, 2021

What is the volume of sound called? ›

We measure sound intensity (also referred to as sound power or sound pressure) in units called decibels. Decibels (dB) are named in honor of Alexander Graham Bell, the inventor of both the telephone and the audiometer.

Which form of energy is sound? ›

Sound energy is the result when a force, either sound or pressure, makes an object or substance vibrate. That energy moves through the substance in waves. Those sound waves are called kinetic mechanical energy.

What is the term for sound volume? ›

dB, decibel - noise of sound measurement is called decibels (dB). Ratio of the sound pressure to reference pressure to something in it. sone - a unit of perceived loudness equal to the loudness of a 1000-hertz tone at 40 dB above threshold, starting with 1 sone.

What is the sound level at Theatre? ›

Movie theaters range from 74 to 104 decibels, which is louder than normal conversation (60–70 decibels), but similar to motorcycles and dirt bikes (80–110), or music playing through headphones at top volume (94–110).

How loud is 70 dB? ›

70 decibels is as loud as a washing machine or a dishwasher. It is a moderate noise level. 70 dB noise is not considered harmful to human hearing. However, extended exposure to levels above 55-60 dB can be considered disturbing or become annoying.

Is 50 dB Loud for a home? ›

50 decibels is a safe, quiet noise level comparable to the following common sounds: A quiet conversation. A quiet office or home. A quiet residential street.

How loud is 96 decibels? ›

Noise SourceDecibel Levelcomment
Boeing 737 or DC-9 aircraft at one nautical mile (6080 ft) before landing (97 dB); power mower (96 dB); motorcycle at 25 ft (90 dB). Newspaper press (97 dB).904 times as loud as 70 dB. Likely damage 8 hr exp
15 more rows

What are the two types of sound in theatre? ›

For sound design, there are two basic kinds of sounds: live/practical or taped/canned. Live sound effects, or practicals, are produced live on or just off stage. These could include door slams, offstage footsteps, explosions, gunshots, thunder, or music made by onstage performers.

How high or low a sound sounds is the? ›

How high or low a sound seems to a listener is its pitch. Pitch, in turn, depends on the frequency of sound waves. High-frequency sound waves produce high-pitched sounds, and low-frequency sound waves produce low-pitched sounds.

How important is sound in theatre? ›

A theatrical production's sound design defines its overall atmosphere and its effectiveness at telling a story. It's a critical component of the narrative and influences the audience's perception of the play.

How many dB is too loud? ›

In general, the louder the sound, the faster NIHL can develop. Sound is measured in units called decibels. Sounds at or below 70 A-weighted decibels (dBA) are generally safe. Long or repeated exposure to sounds at or above 85 dBA can cause hearing loss.

How many decibels is a phone ringing? ›

Studies found that ringtones average 60 decibels from five meters away. At one meter away, phones ring at 76 decibels, and the sound intensity can rise up to 128 decibels when a mobile phone is placed beside the ear!

How much dB is too quiet? ›

That said, appliances with a dBA rating of 38-40 dBA are considered to be silent. Which means you won't hear it over your conversation and other background noise.

How many dB is too loud for Neighbours? ›

Limits are usually around 60 dB, though some locations permit volume at 70 dB. This number may go down late at night and early in the morning. People will rarely stand noise of this decibel level. Walls in some apartments might do a better job of keeping out noise than others.

How many decibels is a TV? ›

While your TV audio fluctuates with the control of your remote, the average television reaches up to 70 decibels (dB), making it generally safe for listening.

Is 70 dB too loud for neighbors? ›

For residential environments, the accepted decibel level is lower. Any noise exceeding 70 dB is considered disturbing. Residential limits usually start at 60 or 55 dB (the equivalent noise of a regular vacuum cleaner). Time limits usually apply after 10 pm and until 7 am.

What happens if you hear 100 decibels? ›

Sound is measured in decibels (dB). A whisper is about 30 dB, normal conversation is about 60 dB, and a motorcycle engine running is about 95 dB. Noise above 70 dB over a prolonged period of time may start to damage your hearing. Loud noise above 120 dB can cause immediate harm to your ears.

How many decibels is a refrigerator? ›

Most fridges have a range of 32 - 47 decibels.

How loud can a human yell? ›

Human screams can be quite loud, possibly exceeding 100 dB (as of March 2019, the world record is 129 dB!) —but you probably want to avoid that because screams that loud can hurt your ears!


1. Sound Level Meter Explained Process
2. Sound Pressure and Decibels
(Simcenter Testing)
3. Sound Pressure, Power, and Intensity
(Simcenter Testing)
4. NTi Audio Webinar - Basics of Sound Level Measurements
(NTi Audio)
5. Lesson 12 - Sound Intensity And Sound Level
(Math and Science)
6. Sound Level Example # 1
(Andrey K)


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