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Safe and effective communications in noisy environments

01 June 2020

HSM and 3M's latest webinar provided valuable insight into Noise Induced Hearing Loss (NIHL).

With the clear risk of hearing damage an ever-present in noisy workplaces, ‘Noise Induced Hearing Loss’ (NIHL) is a rapidly-growing area for litigation and insurance claims. However, the effects to the individual can be profound and life-changing. 

A webinar, hosted by Western Business Media in partnership with 3M, provided an overview of the importance of hearing conservation, and an introduction to a range of solutions that can aid compliance, communication, situational awareness and productivity.

The panel comprised Mohammed Saleem, senior technical specialist, 3M and Stephen Ellis, technical service engineer, 3M, and Emma Shanks, senior scientist for noise & hand-arm vibration, at The Health & Safety Executive.

Mohammed Saleem began the webinar by providing some key statistics, warning that NIH is on the increase. "Approximately 5% of the world’s population suffers from disabling hearing loss, which means experiencing damage of 40dB or more in one of the two ears," he said.

"Across Europe there are 13 million people who suffer from some kind of hearing disorder and, in the UK alone, more than 23,000 people have a work related hearing problem. This has a direct impact on our every day lives, wellbeing and employability.

"More recently, an additional factor has been the increased use of in-ear devices for steaming music, particularly among the younger population. It doesn’t take long to suffer from long term damage if people are listening to high levels of music day in and day out. This has an impact on both our work and home lives."

According to Saleem, the top occupational disease reported by the Department of Work and Pension is NIHL, which is by far the biggest of any industrial related disease. He observed: "Because it is insidious and worsens over a long period of time, people tend not to think about it - until it’s too late."

How do we hear?
Providing a basic overview, Saleem explained: "Sound travels through the ear canal, striking the three bones, and the oscillations are then transferred into the cochlea where there are more than 20,000 inner hair cells which process the sound into a signal.

"Inside the cochlea there are three separate layers of outer hair cells, with one layer of inner hair cells. The purpose of the outer cells is to gather, amplify and fine tune the sound before passing it on to the inner hair cells. Over a sustained period of time, the outer hair cells will eventually die and will no longer be able to direct sound into the inner ear.

"This is a gradual process and occurs over a period of time if someone is exposed to a high level of sound - with the exception of acoustic trauma, where there is a sudden large peak impulse noise which could bring about irreversible health."

Effects of noise induced hearing loss
There are a number of effects of NIHL, such as difficulty in hearing quiet sounds, conversations sounding muffled, and the need to ask others to repeat themselves. As a result of this, Saleem believes it often brings about a loss in self esteem, loss in productivity, fatigue and anxiety: NIHL sufferers will also demonstrate symptoms of Tinnitus, a psychological phenomena which is amplified at night when external sounds have been reduced. An article published by the Alzheimer’s Society even suggested a connection between NIHL and the development of dementia. In some heavy industries it’s not untypical to experience very high noise levels. This is clearly a wake up call."

With such a plethora of hearing protection equipment available - ranging from ear plugs to a multitude of headsets - in terms of the critical aspects of auditory awareness, if someone is working on a busy shop floor it’s important that they are able to detect sound that’s dangerous, to pinpoint where it’s coming from, and how far away it is.

However, as Saleem explained, things can go wrong. 

"The Health & Safety Executive (HSE) published a report from between 1998 and 2015 which involved the investigation of 11 incidents, one of which was fatal, Saleem asserted.

"One of the key factors in the report was to examine whether audibility in important signals was compromised, and whether the operators were wearing the right safety equipment. In this context, the main question is whether they were able to maintain situational awareness and could that have potentially contributed to the incident? This plays a key role in any HSE investigation."

Situational awareness and communication 

Stephen Ellis technical service engineer at 3M continued the presentation to analyse the importance of situational awareness. 

Ellis explained: "Human speech falls in the area of between 60 and 70dB, which is relatively low. If you consider that moderate-to-high industrial noise ranges from 80 to 90dB it’s easy to understand how industrial noise can mask human speech and make conversation impossible."

He continued: "The problem remains when we deploy hearing protection devices, such as earplugs or earmuffs. These devices simply reduce the level of sound entering the ear, but also the level of voices by the same ratio, making speech even more difficult. In a typical work situation, people will often lift off their hearing protector headset in order to speak to each other, therefore exposing themselves to physical harm."

Ellis listed four advantages of using a combination of hearing protection and communication devices:

  1. The potential to improve productivity: This enables more effective communication and allows operators to talk while they work, hands-free, and reduces downtime
  2. Helping to reduce waste: Enabling more effective communication in a production line
  3. Improving worker safety: Creating a better awareness of each other and, if needs be to call for help
  4. Maintaining motivation: Providing better awareness and improved team spirit. 

Among the range of products that can help, Ellis suggested headsets and other devices that provide a level dependent function: "If you imagine a workplace that has a variety of different activities going on, such as metal working or intermittent angle grinding, with this amount of noise that could potentially harm hearing there needs to be a large amount of cooperation between the different workers - and they will need to speak to each other.

"The level dependent function incorporates microphones that listen to the ambient sound, and this sound is processed by the electronics inside the device, which are then reproduced inside the headset. A device is built in that limits the level of the sound to 82dB in the earphones, and irrespective of the sound outside, that level will never be exceeded.

"There is also the advantage of directional situational awareness, as all these products work in stereo mode, mimicking the way the human ear works. This enables the device to detect the direction of sound and, with intermittent sound enables users to communicate with each other when the noise has stopped."

Headsets such as the 3M Peltor ProTac III uses this principal, with the microphone on the outside and internal analogue or digital signal processing. The headsets are designed to be lightweight, portable, and the level dependent feature is provided as a supplementary in-ear device option.

Ellis continued: "This device is much more versatile when it comes to interoperability with other types of PPE - it can be used as a standalone piece of PPE."

Two way communication solutions

According to Ellis, level dependent devices work extremely well with intermittent noise sources. He explained: "For continuous loud noise, the system behaves in the same way as the human ear, and compresses all the sounds - both ambient and speech - together. In situations where workers are in environments in excess of 90dB, but they still need to speak to each other, the solution is a two way communication system. 

"3M standard two-way communication headsets are specifically designed for industrial users in high-noise environments. Incorporating 3M Peltor technology, the battery powered hearing protection headset has an integrated two-way walkie talkie, and is equipped with a noise cancelling microphone that doesn’t pick up and transmit the nuisance ambient noise. We have developed a system called a differential noise cancelling microphone that satisfies these requirements. 

"Some of these headsets also have a level dependent system built in, the purpose of which is to allow the user to have a situational awareness of evacuation alarms or potential hazards such as moving machinery. The headset provides outstanding communication in very high noise environments and, in a recent study, by using the 3M Peltor WS LiteCom headsets, workers in a civil engineering project for a global construction firm reported that downtime and interruptions were reduced by 19%. The beam-mounted earphones provide minimal resonance and distortion, offering excellent sound reproduction even in high-noise environments."

Fit testing

With any item of PPE, it’s important that the right one is selected, depending on the individual and the hazards. This, noted Mohammed Saleem, is particularly important in the context of situational awareness and communication.

He said: "Fit testing plays a valuable role in the hearing conservation programme, and testing is applicable to both passive and electronic devices. It helps people to understand the importance of correct selection and, more importantly, the fitting technique usage.

"Fit testing is a powerful educational and awareness tool and there are a number of systems. Some are subjective, which are based on the REAT concept. In this process, the dominant ear will be the one perceiving the highest sound levels. Ear dominance at each frequency will be controlled by the ear that has the least attenuation, offset by any differences between the absolute thresholds in the two ears. 

"The objective system is based on using a field microphone in real ear (F-MIRE) method, where you are simultaneously measuring the sound level outside and inside the specially adapted hearing protector. The difference between the two is individual personal attenuation. 

"The 3m E-A-Rfit Dual-Ear Validation System measures how well the hearing protector is working for each employee. The noise reduction provided by the hearing protector is measured directly and objectively, without the need for the employee to listen or respond to the test signals. It takes just seconds to measure the noise reduction at seven different frequencies for both ears at the same time. Once the measurement is completed, the software calculates and displays an overall performance rating for each employee, known as the Personal Attenuation Rating or PAR."

Concluding the presentation, Saleem observed: "Fit testing is not mandatory in the UK but it is often seen as best practice, particularly in the context of the change in categorisation of hearing protection, which has been redefined as “harmful noise” under the PPE Regulation. It has now been placed in the same health risk category as respiratory protection, for which fit testing is mandatory."

Health & Safety Executive Q&As

Throughout the webinar, viewers emailed a range of questions for The HSE's senior scientist for noise & hand-arm vibration, Emma Shanks. At the conclusion of the presentations, she provided her expert analysis on a range of topics. 

Q: NIHL is a problem on construction sites. However, with an increase in the amount of personal audio equipment and the risk this poses, how can we determine which is the cause of NIHL?

ES: This should not be happening because the employer had a duty to look after their employees’ health. If the employee is using personal audio equipment, the employer has absolutely no way of knowing what level of noise they are being exposed to.

In terms of health surveillance and monitoring, this is very much dictated by the Control of Noise at Work Act, and the company’s own corporate guidelines on safety and health management.

Q: Can you give advice regarding the optimum noise level for commercial gyms and management of self-employed fitness instructions?

ES: I would recommend viewing the HSE guidance document for the Control of Noise at Work Regulations 2005 - L108, which is available on the HSE website. Self-employed people are subject to the Control of Noise at Work Regulations in the same way as an employer who has employees - they are viewed as both.

The environment in a gym can be noisy and quite reverberant, and there are control measures that can be taken by either the owner of the building or those who are using it.

There is a duty on the self-employed to take care of their health and their hearing - and also duty on the people bringing them into that building to do the same - so this brings us to risk assessment. It’s about establishing what the risk is and how it is going to be controlled.

Q: What advice do you have on hearing protection for people wearing hearing aids?

ES: This can be challenging, and there’s often a myth that people with hearing aids do not need to wear them while wearing hearing protection.

Hearing aids do not replace the hearing that’s lost, they amplify what’s left. Therefore, if someone is working in a noisy environment where hearing protection is the only way that they can have the exposure to noise control, then that hearing protector does need to be worn at the same time as a hearing aid. This is where it gets tricky, because the compatibility between the two devices can be a difficult marriage to manage, often due to the type of hearing aid being used. There are often reports of feedback.

The HSE is currently preparing an FAQ on this subject and, with an ageing population of people naturally losing their hearing, this is a question we’re regularly asked. 

You can view the webinar On Demand for free by visiting https://events.streamgo.co.uk/safe-and-effective-communications