Sound Advice Note 10

Background

10.1 This advice deals with events where live amplified music is performed to an audience, referred to here as 'rock and pop'. However it covers a huge variety of music genres and instrument types, including set-ups that may normally be thought of as classical or orchestral. The prime consideration is the use of amplification and sound-reinforcement equipment in live performance.

10.2 The number of people in this sector who are already suffering from noise-induced problems such as hearing loss, tinnitus and other permanent medical complaints is proof that this is in a hazardous environment and personal hearing damage does occur.

10.3 This advice outlines practical approaches to noise control and noise exposure reduction that can be considered good practice. It does not consider in detail using personal hearing protection. However, it is highly likely that hearing protection will need to be used as well as the noise control measures outlined (see Sound Advice Note 5 Personal hearing protection).

10.4 There is a common misunderstanding in the rock and pop world that Regulations concerning noise levels solely refer to issues of noise pollution and neighbourhood disturbance caused by spill from concert and event venues. However, as explained in Sound advice note 2 Responsibilities, where people are at work (including the self-employed) then there is a legal obligation for employers, event organisers and the self-employed to control noise levels to protect the health and safety of workers - even if that noise is something deliberately generated and people are willing to expose themselves to potentially damaging levels of noise.

Noise risk assessments

10.5 A noise risk assessment flowchart for planning a rock/pop event is shown at the end of this advice note.

10.6 The tables below give typical noise levels and noise exposures for a range of people working with amplified live music.

Representative noise levels

Noise Source	dB	Peak
Percussion	90 - 105	124-146
Amplified guitar (on stage using in-ear monitors)	100 - 106*	118
Amplified guitar (on stage with wedge monitors)	105 - 112*	124
Drummer at indoor music festival	105	144
Guitarist at indoor music festival	103	146
Bass guitarist at indoor music festival	101	133
Several musicians
Amplified rock music	102 - 108*	140 and above
* at 3 m

Representative exposure levels

Occupation	dB	Peak
Indoor/stadium music festivals
Monitor engineer	96 - 104	147
Production manager	101	146
Keyboard technician	101	145
FOH sound engineer	99 - 100	139/145
Promoter's representative	96 - 100	146
Pit supervisor	102	140
Stage manager	96 - 98	137
Lighting chief	94	146
Security staff (depending on location)	89 - 94	137/146
Security - Pit	100	146
Catering staff	91	134
Fire officer	101	144
Cashier	89	131
Events manager	85 - 87	137
Film crew	98 - 100	139/143
Merchandise staff	100	134
Bar staff	96 - 97	131/136
House managers	80 -- 91	131/137
Cloakroom staff	90	145
Outdoor music festivals ('Pop concerts')
Stage manager	98	134
Technicians	91-93	133/138
Catering	87	135
Merchandising	85 - 101	127/146
Security - Pit	91 - 101	136/144
Security staff (depending on location)	85 - 100	122/146
Ambulances	88 - 94	124/133
Bar staff	86	128
Site manager	87	129
Camera operator	100	137
Delay tower engineer	93	125

10.7 Virtually any live event using amplified instruments and sound reinforcement equipment will exceed the upper exposure action value. Therefore, some kind of control measures will almost certainly be required.

10.8 To determine what control measures are necessary, establish:

• What is the source of the noise?
• What specific areas are affected?
• Which workers have to operate in these areas, for example musicians, technical crew, stewards, welfare and medical teams, bars and concessions?

10.9 Carrying out such an assessment for specific locations, instruments, repertoire and venue layout will allow the employer/organiser to prioritise actions and target the areas and employees at highest risk. Where this involves measurement, see also the advice on measuring noise in Sound Advice Note 3 Noise risk assessment and planning.

10.10 Considering noise exposure should form a key part of the planning process, in particular sound system design, speaker location, equipment selection, the acoustic of the venue, the acts/groups, the number and positions of performers, the differences between the different instruments and so on. Planning is particularly important for concert tours and should involve both venue and acts. Taking account of noise issues at an early stage is likely to be both more effective and more economic than simply handing out earplugs to crew once the tour is underway, especially as the performers will probably also need hearing protection.

10.11 A 'pre-event noise risk assessment' may help plan the event. This might include:

• selecting a suitable location for the event;
• selecting a balanced line-up;
• selecting an appropriate design for staging;
• selecting suitable materials to reduce vibration and sound levels on stage;
• design and use of PA systems and amplification;
• starter level of sound in a performance;
• sound checks and rehearsals.

10.12 The design and layout of venues can have a significant effect on noise levels and the noise exposure of individuals (see Sound Advice 8 Venues'). Size and staging, design and building materials, public address systems and the weather can all affect on the sound levels being produced in outdoor venues.

10.13 Venues should have already carried out noise risk assessments for their own staff, and visiting or touring productions should request these to assess where people may be at risk and where special attention needs to be given to noise control.

10.14 Any noise risk assessment should be updated if there are any changes (for example to the set design, venue, seating or line-up/set).

10.15 Where temporary concert stages are established, such as at outdoor festivals or concerts in marquees, assume risk-control measures will be needed. Generic risk-control measures should be put in place as a matter of course and they can then be adapted or modified during the event as necessary. The organisers should assume that the entire stage area, the pit area, the front-of-house control position and any locations adjacent to delay and in-fill speakers are hearing protection zones, even after the control measures have been put in place. See also Sound Advice Note 5 Personal hearing protection.

10.16 For outdoor events and festival sites, the organiser has to consider not only the exposure to people working backstage and on-stage, but should also bear in mind the way site layout may bring other workers, contractors and concessionaires into noisy areas. Taking account of such issues during the site planning stage is crucial, since it is extremely difficult to solve once structures, staff and equipment are in place. Also think about the management of the noise generated by the concessions themselves - many of whom bring their own PA systems and generators. For further information see The event safety guide.

10.17 Also remember that other periods of exposure from non-work activities increase the overall dosage, for example a loud show followed by listening to a personal stereo at reasonable volume. While outlawing personal headsets on the tour bus is clearly drastic, awareness of how and when people are exposed to noise hazard is a fundamental first step to reducing the risk of damage.

Control measures

10.18 The first, simplest and most effective measure is to turn down the volume wherever practicable. Unfortunately this is often overlooked and flies in the face of the 'Rock and Roll' attitude. However, the simple step of keeping levels under control at every stage of the instrument/signal/amplification/reinforcement chain is fundamental.

10.19 Loud stage noise levels can compromise the quality of the performance and the sound that is delivered to the audience. It has been known for stage monitoring levels to be so loud that the front-of-house engineer in an arena has been unable to hear his own mix. This seriously compromises the possibility of creating a suitable mix for the audience. The use of in-ear monitoring can significantly improve the overall sound quality.

On-stage control measures

10.20 On-stage control measures include the following:

• Turning it down does not necessarily mean reducing the overall output of the main PA, but requires an analysis of why things are so noisy and targeting measures to control the main 'offenders'. This is particularly true on-stage where amplification of individual instruments (backline) often competes with on-stage monitoring (fold-back, side fills) and the PA itself.
• Consider substituting quieter instruments and amps in the first place. High-quality amplifiers and speakers that operate without distortion are far preferable to driving inferior systems at higher rates. Introducing distortion makes the output less intelligible and leads to increases in sound level in attempting to achieve clarity. The result is often a spiral of increasing volume without ever achieving clear monitoring.
• Consider increasing distance, isolation or shielding of noisier instruments where possible. Drum kits can be positioned and shielded/enclosed to minimise noise levels for performers and workers situated close by. Ideally shielding should be acoustically absorbent rather than reflective material.
• Position and angle guitar amplifier/speakers (guitar combos) for maximum ease of listening for the player. Additionally simply raising a guitar combo on a flight-case could significantly reduce exposure for other players, have a marked reduction in overall stage noise and improve clarity for the player. Guitar combos could be positioned and mic'd in a separate area from the performance area.
• Consider using technology that eliminates the need for loud backline amplifiers on stage. This could range from simply plugging instruments into a mixing desk by means of Direct Injection (DI) boxes rather than mic'ing up an amplifier, through to using amplifier modelling software, foot pedals or other hardware. Whatever system is used, sound engineers can achieve greater control of on-stage levels through careful management of monitor levels rather than expecting musicians to fight it out in a battle of escalating stage volume.
• Use risers to separate sections of the band, and to elevate particularly noisy instruments above the heads of other performers - or move to the front of the stage, particularly where very loud instruments may be used - brass, amplified guitar and snare drums can produce extremely high sound levels. See 'Risers' in Sound Advice Note 4 Noise control and training.
• A 'shaker' or 'thumper' is especially useful for reducing drum monitor levels. Shakers will allow performers to use hearing protection and monitor their performance while still maintaining contact with their instruments.
• Consider altering the drum kit set-up to ensure cymbals etc are not at ear-height. Experiment with raising or lowering the cymbals as necessary to protect the hearing of everyone who is close by. Try hanging small strips of cloth from each cymbal's centre nut.
• Some drum players are quite happy with headphones/in-ear monitors and a shaker rather than a traditional drum fill. The headphones should be selected to provide hearing protection; the devices that reproduce sound inside the headphones should be limited. This alone may save several dB of overall stage level.
• Damping drum kits can reduce overall noise levels, especially in rehearsals. Methods include:
  • taping small pieces of cloth or other sound-absorbent materials inside the drumheads;
  • placing rubber rings on top of the drumheads;
  • taping small pieces of cloth to the rims so that the cloth lies loosely over the skins;
  • stuffing foam rubber inside the drums or hanging it from the inside of the drumheads;
  • stuffing the bass drum with a pillow, towel or shredded newspaper.
• Use screens where appropriate, particularly where there is orchestral music support to the main rock performance. Care should be taken with acoustic screens, since they can make noise levels higher if positioned incorrectly (see Sound advice note 12 Orchestras).

On-stage monitoring

10.21 The need for musicians to hear their own performance and that of other performers is fundamental, but this can lead to an excessively loud and confusing stage environment if not planned and managed correctly. Monitor systems are often used as a means of overcoming high stage noise, but effort is better put into reducing those levels to achieve clarity rather than boosting other signals.

10.22 On a noisy stage it is very seldom the answer to turn something up to make it clearer. Always start by turning down the overall level and making adjustments in the balance; the human ear just doesn't work well at high noise levels. So, for example, someone asking to hear more vocal in a mix may well just need to hear less of everything else, especially if that noise is spill from other monitor mixes.

10.23 A well-balanced monitor system should allow all the players to hear what they need at a comfortable level while maintaining a reasonable work environment for everyone else on the stage. This needs time and planning, as well as a skilful monitor engineer who understands the needs of musicians. Consider the following:

• Position speakers to provide effective listening levels to the performer(s) concerned without causing excessive spill, which makes it harder for everyone else to hear what they need.
• The layout of performers on the stage can radically affect the levels of exposure from spill that musicians experience. Therefore careful planning of the stage layout may avoid the need for noise competition between monitor mixes and other noise sources. The advice of monitor engineers at this stage is valuable.
• Monitor engineers should use their equipment properly and safely. This means:
  • resisting the temptation to allow stage levels to creep upwards;
  • 'prepping' the system to put the right equipment in the right place;
  • 'ringing out' or tuning the system to identify problem frequencies which may cause rapid and unexpected feedback.
• All sound checks should be carried out with the minimum number of people present.

10.24 Perhaps the most effective means of avoiding monitor spill is to use monitor headphones or in-ear monitors (IEMs). IEMs and monitor headphones allow a very quiet stage environment with benefits for all workers. IEMs have many benefits including clarity, controllability and comfort. It should be noted that generally IEMs and monitor headphones are not classified as personal hearing protection, and although they may provide some protection against external noise, their performance in this respect cannot be guaranteed. The use of limiters IEMs and monitor headphones is strongly recommended.

10.25 Good working practice for monitor headphone and IEM users includes:

• Do not share headphones. Where this cannot be avoided, give users their own ear pads and voice tubes
• Headphones should be fully adjustable and well-maintained.
• Headphones or associated equipment should incorporate an adjustable volume control that enables the user to listen to incoming signals at a comfortable level.
• Clean headphones regularly. Foam pads can be washed, wiping cables prevents them from becoming brittle, and cleaning voice tubes (which can become blocked with food, dust or make-up) ensures the level of transmitted signals remains audible.
• Allow time for users to make adjustments to their equipment, and to clean and maintain it.
• Users need regular training including how to use the headphones and associated equipment, any volume-control features and why adjustment of the listening level through the headphones is important, as well as the importance of regular cleaning and maintenance.
• Reducing ambient noise levels will enable headphone users to keep listening levels as low as possible.

10.26 Similar benefits may be obtained from using small personal monitor speakers that can be placed near a performer rather than relying on a traditional wedge or side-fill at a distance. These are particularly effective for relatively static performers such as keyboards and DJs.

The off-stage environment

10.27 High sound levels can be produced throughout a venue, and the noise risk assessment for an event should identify all the people who are at risk, not just the musicians or stage crew. See The event safety guide for guidance on audience protection. Consider the following:

• The choice and location of speakers can significantly affect sound levels. Technical staff and working crew etc should be protected from unnecessary exposure to high sound levels, for example by ensuring lighting desks are not placed near loudspeakers.
• Re-orientate the stage and/or loudspeakers to direct less sound towards staff locations. Where there are multiple speakers, such as in discos, clubs, concert halls or theatre auditoria, try reducing the sound levels of those speakers nearest staff locations.
• The dispersion pattern of modern speakers enables the 'targeting' of sections of the venue or audience, which in turn means the level at the front of the crowd can be reduced. The total power output from the sound system (for a given audience sound level) can be reduced by using a line array. These loudspeaker systems effectively direct sound in a narrow beam to audience locations, providing a higher quality sound, with less 'spill'. The key is to ensure that speakers, (whether or not technically 'line array') are positioned and aligned to efficiently get sound to the audience and avoid either an excessively high sound level at the front of the audience or needless spill into sensitive areas.
• Where possible, arrange stages and loudspeaker positions to avoid excessive sound levels for bar staff, stewards and other workers. Where a venue has a number of speaker positions around the building, consider the direction and volume from each group of speakers. Those that are close to noise-sensitive locations such as the bar should be individually controllable. For outdoor events and festivals, consider the noise impact on, for example, stewards, security, first-aiders, concessions (not just stage production staff/performers).
• PA systems can be flown or stacked in such a way as to introduce a natural separation between speaker enclosures and staff, making it impossible to get too close to the sound source - this is particularly important for workers in the stage pit and other locations close to speaker stacks. Spill from sidefills and other on-stage sources can also be a problem for pit teams.
• A similar effect can be achieved by means of barriers around speaker positions. This approach is of particular value when considering protection of the public and front-of-house staff.
• 'Satellite' or 'delay' stacks are speaker clusters placed at some considerable distance into the audience from the main speaker positions and to which the signal is delayed to make it coincide with the sound travelling from the main speakers. Therefore the sound is reinforced and intelligible a long way back from the stage and the level at the front can be reduced because the noise from those speakers no longer has to reach all the way to the back. This is an example of how good planning can both tackle a noise hazard and enhance the public enjoyment of a show.
• Noise limiters can be used to set a maximum permissible output level for the sound system. While normally used to manage noise pollution from a venue, the same set-up could be employed to limit the maximum front-of-house or stage sound output.
• At festival sites concessions and other commercial operations often have their own PA systems. The event organiser should ensure that the output of such systems is managed along agreed guidelines taking account of the potential combined effect of several systems, to minimise the noise exposure of employees on site, including those working on concessions' stalls.
• If radio headsets are in use, they should provide hearing protection and be limited (see Sound Advice 15 Studios).

Stage pits

10.28 On large pop concert stages and outdoor events it is common to find a fence line restraining the crowd a few metres in front of the stage itself. This is the 'pit barrier' and creates an area called the 'stage pit' in which stewards, security and welfare staff can help the crowd - and which commonly hosts photographers and media crew. The noise levels found in even small stage pits are so high that staff are liable to exposure well above either upper exposure action value - even if they are only present for a brief period (speaker and audience noise together can easily exceed 120 dB).

10.29 Stage pits should be hearing protection zones with access only granted to authorised personnel equipped with appropriate hearing protection.

Pre-show, sound checks and schedules

10.30 Careful planning may mean some tasks can be completed when there is no noise hazard, for example ensuring that lighting focusing and sound checking are carried out at different times.

10.31 Sound checks are a vital part of the event set-up process, but they are also a mechanism by which technicians and players receive additional exposure to high noise, particularly if the sound check is not properly managed. Ideally instruments will be individually checked at a realistic volume and then an ensemble piece played at full concert level which can usually be set at a lower on-stage volume. A sound check at full concert levels should only be necessary for balancing sound levels, as distinct from rehearsals or last minute run-throughs of sets.

10.32 From a noise exposure perspective it is essential to limit both the duration and volume of sound checks. Similarly, limiting the number of non-essential personnel on stage and in the auditorium during a sound check will have time-management as well as noise exposure benefits. Every venue or event should have somewhere quiet for musicians and crew to take breaks or rest periods.

10.33 The sound check is a good opportunity to identify any unexpected or particularly troublesome noise elements. This could be achieved by monitoring sound levels at specific representative reference positions.

Example of an outdoor music event showing reference positions for noise measurement

10.34 Remember that the sound check is not solely for the purpose of musicians - it is often the only opportunity for front-of-house and monitor engineers to set their systems to achieve an optimum mix and safe playback levels.

10.35 Awareness of loud noise as dangerous means that crew should only be in the immediate vicinity of the stage during noisy periods if their job specifically requires it. The stage should not be used as a viewing platform or rest area for off-duty crew. It is a high-risk environment to which access must be strictly controlled.

10.36 The way in which work tasks are scheduled can have a significant impact on personal noise exposure over time. When planning the individual work, a load-in and show, or even an entire tour, consider when, where and to whom noise exposures will occur. Organise the work to ensure that personal noise doses are kept as low as reasonably practicable. This might be achieved by:

• balancing loud and quiet activities for example, show and offsite duties;
• ensuring that staff take breaks and rest periods away from loud noise areas;
• rotating staff to limit exposure time (particularly useful for stewards and security staff);
• limiting any recorded music to predetermined levels, and monitoring and controlling it. Keep recorded music as low as practicable, especially between acts, to reduce overall exposure;
• venue managers scheduling shows to ensure that staff have a balance between loud and more moderate events.

Noise risk assessment for amplified live music

10A1 In-ear monitors

1. Additional information to that referred to in paragraphs 10.24 and 10.25 on in-ear monitors (IEMs) is provided below:

   Advantages

   • Help towards a very quiet stage environment with benefits of clarity, controllability and comfort.
   • Custom-moulded earplug protects against undesired background sound.
   • Belt-clip transmitter-receiver feeds direct signal into ears, eliminating need for on-stage monitors and reducing on-stage sound levels.
   • Wireless transmitter-receiver provides freedom of movement.
   • Smaller and lighter than headphone monitors.

   Disadvantages

   • More expensive than headphones.
   • Training essential.
   • Dangerous unless limited.
   • May not be suitable with some medical conditions.

   Useful for

   • Reduction of noise exposure during live music performances.
   • Personalised monitoring.
   

   Custom-fit in-ear monitors

2. IEMs are essentially earplugs with built-in miniature monitor speakers. IEMs receive an audio signal from a wireless transmitter-receiver system to earplugs moulded to the shape of the user's ear canals. Less expensive IEMs may use 'ear buds' rather than custom-moulded plugs but these should never be used for hearing protection because the earpieces do not fit snugly and so will let in more outside sound, which leads in turn to higher, rather than lower, monitor levels.
3. In-ear monitors intended to provide hearing protection must comply with BS EN 352-2 and any other appropriate parts. This will ensure that IEMs provide hearing protection from ambient sources and provide noise limitation of the signal received from the communication system. Custom-moulded earplugs need to fit tightly beyond the second bend in the ear canal or they will not keep out all background sound. An improper fit could cause the user to turn the IEMs up to overcome the undesired background sound unless a noise limiter is fitted. It is essential that IEMs are fitted with noise limiters to reduce the risk of damaging sound levels being delivered to the wearer.
4. Training in how to use IEMs is essential to avoid turning a potential benefit into a hazard. It is essential that users keep the volume down to a reasonable level rather than turning it up because they like it loud. The systems require planning, set-up and a moderate initial investment, but if used effectively the benefits outweigh the costs.

Glossary

For a more detailed explanation of terms see Useful information and glossary.

Backline: Collection of musical instruments and their direct amplification on stage.

Exposure action values: Levels of exposure to noise at which certain actions are required (see Useful information and glossary).

Hearing Protection Zones: Areas where the wearing of hearing protection is compulsory (see Useful information and glossary).

In-ear monitors: Essentially earplugs with built-in miniature monitors (loudspeakers). It is essential that they are fitted with noise limiters.

Noise dose: See noise exposure.

Noise exposure: 'The noise dose', which can be calculated, takes account of both the actual volume of sound and how long it continues. Noise exposure is not the same as sound level, which is the level of noise measured at a particular moment.

Noise limiters: Sometimes known as volume regulatory device (VRD), controls noise exposure from amplified music. Modern noise limiters can be fitted with anti-tamper relays connected to external switches to improve system security.

PA: Public address system. Sometimes called a 'Tannoy'. Often used to refer to any loudspeaker transmitting messages rather than music.

Stage pit: In large pop concert stages and outdoor events, an area in front of the stage formed by the edge of the stage and a barrier a few metres away, which restrains the crowd.

Reference position: Standard location, usually static, selected to enable monitoring of noise levels to be conducted by measurements.

Shakers (or thumpers): An attachment that fits directly to the drum stool and transmits low frequency vibration - giving the player the right 'feel' without the need for high volume bass speakers, effectively a loudspeaker without a cone. (see Useful information and glossary).

Tinnitus: Buzzing, ringing or tone in the ear. Temporary tinnitus is a warning; a sign that 'you got away with it that time.

Upper exposure action value: See 'exposure action values'.

VRD: Volume regulatory device, (see noise limiter).

Bibliography