Measurement sound level meters

Noise monitoring is usually located in the HASP as part of the monitoring program. Noise monitoring should be performed in accordance with acceptable practices. Typically, noise levels are monitored in the field with either a Type I or Type II sound level meter (SLM). Noise dosimeter readings can also be obtained to determine the percent (%) noise dose. Noise levels and % doses measured are then compared to limits listed in OSHA standard 29 CFR 1910.95, Hearing Conservation [3]. 

The sensor is the element of an instrument directly influenced by the measured quantity. In temperature measurement the thermal mass (capacity) of the sensor usually determines the meter s dynamics. The same applies to thermal anemometers. In IR analyzers used for concentration measurement, the volume of the flow cell and the sample flow rate are the critical factors. Some instruments, like sound-level meters, respond very fast, and follow the pressure changes up to several kHz. 

Weighting A The frequency-selective device on a sound level meter used to measure the A frequency network. 

The simplest sound level meter consists of a microphone, an amplifier and a meter of some type. Sound level meters are graded according to British and international standards, and the most common type used for accurate measurement purposes it known as the Precision Grade or Type 1 meter. In practice, a basic sound level meter will incorporate weighting networks with either in-built octave filters or provision for connecting an external filter set (Figure 42.6). 

Portable sound level meters are also available which can measure percentiles. These either hold the results in a memory which can be separately interrogated or may be connected to a computer for a printout. Larger machines (known as environmental noise analyzers) are available which can record percentiles and Leq readings and produce a printout. These are resistant to weather and can be left on-site for up to a week. 

In practice, measurements are made with the use of an accelerometer. This device is connected to a sound level meter and may make measurements of acceleration in terms of decibels (or by changing scales or use of a device similar to a slide mle, in direct terms). An integrator can be connected between the accelerometer and the meter to express the results in terms of velocity or displacement. 

The noise level was also measured using Interacting Sound Level Meter (NL04) from RION for blower speed setting of normal-speed near the inlet and outlet of the Prototype Unit. The average noise levels are 23 and 48 dB at the inlet and outlet, respectively. These values are low compared to most air dehumidifier and air purifier appliances. 

Both OSHA and the EPA have provided information on permissible noise exposures. Protection from noise is required when sound levels exceed those provided below. These are measured on the A scale at a slow response on a standard sound-level meter (except for certain alarms, etc.) as provided by OSHA. 

Sound level level of sound measured with a sound level meter and one of its weighting networks. When A-weighting is used, the sound level is given in dBA. 

Sound level meter an electronic instrument for measuring RMS of sound in accordance with an accepted national or international standard. 

Noise of a constant level as measured over at least one second using the slow setting on a sound level meter. Note that a noise that is intermittent, e.g., on for over a second and then off for a period, would be both variable and continuous. 

A device to measure instant noise levels. It is comprised of a microphone, amplifier, output meter, and frequency-weighting networks, which are used for the measurement of noise and sound levels. Sound-level meters are often made with various filtering networks that measure the sound directly on A, B, C, etc., scales. Sound-level meters may also incorporate octave-band filters for measuring sound directly in octave bands. Since sound levels are specific to the areas being measured, the sound levels are called area sampling. Sound level meters used for measuring noise for compliance requirements must meet American National Standards Institute (ANSI) Standard S1.4, Specifications for Sound Level Meters. See also Noise Dosimeter Weighted Measurements. 

Where sound levels exceed the PNEs, you must also implement a hearing conservation program. An effective program monitors employee exposure, administers annual audiograms, trains workers, and maintains proper recordkeeping. You should keep records on the noise created by different machines and operations at your construction site. Measurements should be taken with a sound level meter, at slow response, measured on the A-scale. 

Impulse Meter Sound level meters do not respond quickly enough for measurement of impulse sounds. Impulse meters provide this quick response. They give readings in decibels for peak levels of transient sound. 

The other type of survey has the purpose of finding out if conditions could create excessive exposures. In this kind of survey, measurements taken at various locations help determine noise sources or potential noise exposures at locations where people may be. During a survey, a user takes readings with a sound level meter in a grid pattern or at specific worker locations. The survey data then help with decisions on reducing noise exposures. 

The 3M Sound Detector SD-200 is a compact, lightweight sound level meter designed for measurement of workplace noise levels. Its intuitive design makes it easy to measure sound levels and determine the level of hearing protection that may be required. 

Make the maximum noise level of the equipment 80 dBA, 8 Hour Time Weighted Average when measured on the A scale of a standard sound level meter or noise dosimeter within 3 feet of the equipment. 

The majority of noise control work undertaken by the safety adviser will involve the measurement and possibly the analysis of noise. It is therefore important that the use and the limitations of sound pressure level measurements and sound level meters are understood. Errors in measurement technique or interpretation could lead to costly mistakes or over-specifying in remedial measures. 

The difference between the two available grades of sound level meter, precision and industrial, is effectively the degree of accuracy of the measurements particularly at high and low frequency. Meters should comply with British Standards or with lEC recommendations. 

For the operation of sound level meters of different types the safety adviser should refer to the manufacturer s instruction book. The prime requirement for any instrument for noise measurement is that it should not be more sophisticated than necessary and it should be easy to use and calibrate. A typical sound level meter for use by the safety adviser should have the facility for measuring dBA and octave band sound pressure levels. 

Sound level meter An instrument that measures sound levels. 

The new OHD/Cirrus Research Optimus RTA Sound Level Meter measures all data in one measurement this includes the entire 120dB dynamic range. Just press three buttons, and you re done. Voice tag allows you to audibly notate the measurement, which means no need for keeping track of a log sheet. Tbe Optimus is small, lightweight and incredibly easy to use. Occupational Health Dynamics, www.ohdusacom/products/ sound level meters/optimus.php. Cnvfe 307... 

Noise is measured using a sound level meter which reads sound pressure levels in dB(A) and the peak... 

Are noise levels measured with a sound level meter or an octave band analyzer, and are records being kept ... 

Impulse noise Noise comprising rapid increases (of at least 5 to 10dB) of short duration in the sound level. The impulse sound level Lj can be measured with appropriate equipment. If an ordinary sound level meter (not an impulse sound level meter) is used for determining the equivalent continuous level L, the measured value should be increased by 6dB. 

Averaging can be done with the aid of the rating factors g if the measured values have been obtained by successive readings on a hand-held sound level meter ... 

Quite often, integrating measuring instruments are used in combination with sound level meters, or the necessary averaging calculations may be performed by an electronic computer. 

The CEL-630 Sound Level Meter from Casella CEL simplifies the task of measuring workplace and environmental noise. It provides the operator with simultaneous overall average decibel level results along with a time history record of the noise level with one-second resolution, as well as a frequency breakdown (spectrum) to further quantify specific noise hazards. Casella CEL, www.casellausajcom, (800) 366-2966. Cmde 2SV... 

At any one location, a complete physical description of the noise environment might include its noise level at various frequencies as a function of time. It is common practice to simplify this multidimensional description by eliminating the frequency variable and measuring the A-weighted noise level, as observed on a standard sound level meter.The A-weighting filter emphasizes the mid-frequency components of the noise and demphasizes the low-frequency components in order to approximate the sensitivity of the human ear. 

For certain applications, it is also common practice to further simplify this multidimensional description by eliminating the temporal variable and measuring the equivalent sound level (Leq) or OSHA sound level (Tosha) time average sound level, as observed on standard dosimeters and modern sound level meters. Leq is often used in community noise analysis. It is also used during the analysis of employee noise exposures in many countries other than the United States. Tosha is often used in employee noise exposure analysis in the United States. 

The simplest instrument available to measure sound levels is a sound level meter. There are four different classifications of portable sound level meters ... 

Sound level meters measure noise only at a given point at the time of observation. If the noise being measured is constant in both space and time, meters will give an accurate representation of the situation. However, if the sound level changes with time and location (for instance, as an operator moves around), it will be necessary to record either the sound level manually using short time intervals (5 to 10 s) or the noise data for later analysis of the time history of the noise. The second approach is preferable when a worker s noise exposure is related to duty cycles or product flow. In this case, extrapolations can be made on the basis of total day production to determine the noise exposure of an employee over a full day. 

Configure the sound level meter to read in dB(A) and take a number of measurements at individual workstations. Take the average of the readings at each woikstation. 

---