Sound Level Meter vs Noise Dosimeter: What's the Difference?

The Importance of Noise Monitoring

Occupational noise pollution continues to rise, primarily attributed to rapid growth of industries and their expansion. As a result, concerns regarding noise pollution continues to grow given its direct implications on the well-being, safety, and productivity of individuals within the work environment. According to the Australian Work Health Safety (WHS) regulations, business owners must regularly undertake noise assessments to monitor and mitigate the noise exposure risks to workers. This is a legal requirement which has been implemented to protect workers from the adverse effects of excessive noise exposure such as hearing loss and other health issues.

In Australia, the exposure standards in accordance with AS/NZS 1269.1 are:

• L_Aeq,8h of 85 dB (A). This refers to the noise exposure over 8 hours, considering both the noise level and length of exposure.
• L_Cpeak,8h of 140 dB (C). This refers to peak level noises occurring during work, which have the risk of long-term harm.

Safe Work Australia has set an exposure standard of 85 dB (A) over an 8-hour average for occupational noise. Noise exposure above 80 dB can cause long term health problems and put workers at risk of gradual noise-induced hearing loss or hearing damage. Peak noise levels above 140 dB (C) can occur with explosive noise, leading to instant hearing damage. Health issues caused and associated with high levels of noise level exposure include:

• Tinnitus - ringing in the ears and head
• Acoustic neuroma - benign tumours located on the acoustic nerve
• Vertigo - dizziness and nausea

The table below highlights common noise sources and their typical sound level:

Noise exposure is monitored most significantly using a sound level meter or a noise dosimeter. Both instruments are used to undertake sound level monitoring in different environments, with the overall aim of upholding health and safety standards. But the central question managers and business owners have is, what is the difference? Both a sound level meter and a noise dosimeter can be used to help protect workers from high noise exposure, but the key differences must be understood to determine when you should be using either device.

Sound Level Meters

What is a Sound Level Meter?

A sound level meter (SLM) is a small, handheld instrument that measures the noise intensity of a particular area or process in dB (decibels). Its primary aim is to quantify the sound pressure level (SPL) or overall loudness of sound in an environment to protect individuals’ long-term health and meet safety standards.

Sound level meters such as the SKC SoundCHEK Connect and the SoundProTM SE & DL Sound Level Meter are designed to provide comprehensive real-time data storing and analysis in relation to sound exposure in an environment.

How does a Sound Level Meter work?

SLMs are a battery-operated, and consist of a microphone, electronic circuitry, and display unit. Sound waves are captured by the microphone and converted into electrical signals. These signals are then used to calculate the sound pressure level. The result is displayed on the unit, providing instant quantitative data.

SLMs are manufactured in two different performance categories, Class 1 and Class 2. The two categories follow the International Standard IEC 61672-1:2002, which gives specifications based on the performance of three types of sound measuring instruments, as well as their classification of performance category. Class 1 sound level meters are precision grade meters, meeting a high level of performance criteria. This allows Class 1 devices to be used in situations where accuracy and precision is required. In contrast, Class 2 devices are general grade meters, meeting a lower level of performance criteria and as a result, more suitable to general or recreational noise monitoring.

Sound Level Meter Applications

SLMs are most commonly used for noise evaluations of workplaces, as well as environmental noise monitoring. They are significantly used in industries with high noise exposure such as construction, mining, manufacturing, entertainment, and industrial. These instruments are vital in the protection of workers within these industries, identifying hazards to mitigate and manage risks. SLMs can allow workplaces to:

• Protect workers from long-term hearing loss and internal damage,
• Reduce stress and anxiety of loud workplaces,
• Improve the productivity and concentration of workers,
• Improve communication.

SLMs are ideal in a situation where a particular area or sites noise level needs to be measured. An example of this is a construction site, where a SLM can be used to monitor the noise exposure of the site to establish the effect on the workers, as well as the possible effects on surrounding areas.

Noise Dosimeters: Measuring Individual Exposure

What is a Noise Dosimeter?

A noise dosimeter or noise dosemeter is a small, cable-free device worn on a worker’s shoulder to measure the specific individuals direct noise exposure. They are worn clipped to a worker’s shirt, in close proximity to the ear, to gain an accurate representation of the noise level the individual is experiencing within the workplace. Noise dosimeters store measurements of sound levels throughout a workday, providing an average noise exposure reading for the certain time period. Measurements captured by the device can provide a detailed and accurate analysis of daily exposure patterns, highlighting any risks. Noise dosimeters also have the ability to provide the following parameters:/p>

• Maximum and minimum sound pressure levels,
• Statistical data,
• Graphical representations of the data.

How does a Noise Dosimeter work?

Noise dosimeters consist of a microphone, an integrated circuit for the processing of signals, and a memory unit for data storage. The microphone is secured to the exterior of an individual’s clothing, joined with a cable to the unit itself. The device samples the noise levels regularly in intervals, typically in one-minute average segments, and calculates the time-weighted average noise exposure over the selected period. The data history of the device can be viewed when downloaded, allowing periods of high noise level to be analysed.

Noise Dosimeters such as the SKC NoiseCHEK noise dosimeter and the TSI THE EDGETM5 Intrinsically Safe Dosimeter are designed to be lightweight and cable free generally weighing around 85-115 grams to ensure they are comfortable and non-intrusive for workers to wear throughout their workday.

Key differences between a Sound Level Meter and a Noise Dosimeter

1. Measurement approach

   Sound level meters measure current levels of sound pressure within an environment in dB (decibels), proving immediate results. This immediate feedback allows SLMs to be used for short-term noise measurements. In contrast, noise dosimeters measure an individual’s average exposure over a particular period, taking into account both the intensity and duration of the noise. This provides a longer-term insight into the noise levels.

2. Data presentation

   Sound level meters display the current changing data on screen during the measurement period, allowing an immediate understanding of the noise level throughout the monitoring. Noise dosimeters on the contrary provide data over a time period such as the time-weighted average, which is essential for a long-term assessment of health risks and meeting compliance and regulation standards.

3. Portability and wearability

   Sound level meters are generally handheld or mounted devices, often requiring an operator to hold them in place and monitor their measurement. In contrast, noise dosimeters are wearable devices that can be attached to an individual’s clothing, offering flexibility and convenience.

Air-Met Scientific are distributors of sound level meters and noise dosimeters from a range of leading brands including SKC Inc. and TSI Inc. and are available for sale and rental. Contact your local Air-Met Scientific office today.