Trampoline Park Noise Control: The Empty Hour Is Loudest

The noise complaint that threatens a trampoline park is usually not about children. It is about machinery, measured at night, in a building with nobody in it.

That is not a rhetorical inversion. Crowd noise is intermittent, it arrives in the daytime, and it is partly masked by traffic, weather and the building’s own services. Plant noise is continuous, often tonal, and is judged against a background that collapses after closing. A condensing unit nobody notices at four in the afternoon becomes the loudest thing on the block at midnight, because everything else stopped.

The second inversion sits inside the box. In a trampoline park, the room is a louder source than the equipment. A 2,000 m² shell (21,528 sq ft) with a 6 m ceiling and hard surfaces computes to about 7.6 seconds of reverberation. Bringing that figure to 2.1 seconds removes roughly 5.6 dB from the sound field that reaches the demising wall, which is often the difference between a marginal condition and a compliant one, and it costs a fraction of rebuilding the wall.

The third inversion is geometric. Indoors, moving a noisy zone further from a neighbour stops helping much sooner than most layout drawings assume: at about 3.2 m in an untreated shell, and about 6.7 m once the room is treated. Past that distance you are standing in the reverberant field, where the level is roughly the same everywhere in the room.

What follows works through those three mechanisms in the order a project actually meets them, with the arithmetic shown so you can run it on your own building. It does not quote a target dB(A) for a trampoline park, because we could not find a published measurement of one, and any supplier who hands you a single number for a whole venue is guessing.

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1. Two noise problems share one building

Acoustic failures in this sector almost always trace back to a design team solving one problem and believing it solved both.

Problem one: occupancy noise Jumpers, shouting, whistles, the PA, arcade cabinets, airbags emptying. It arrives in bursts, peaks on Saturday afternoons, and is what everyone pictures when they say the venue is loud.

Problem two: building services Supply and extract fans, dehumidification, chillers and condensing units, car park extract. These run whenever the building is conditioned, which in a sealed box with a moisture load from mats and bodies means most of the night as well.

Each of those two problems is judged under a different set of rules, and using the wrong one is where budgets go wrong. Planning or environmental health assesses the venue against a neighbour criterion, usually a rating level compared with the existing background. Workplace regulation assesses the exposure of the people who work there. Internal comfort criteria describe what the room sounds like to a customer. And the lease can impose its own limit, at a demising wall or at a residential receptor, which is a private contract and can be stricter than any of the other three.

The lease is the one that closes venues. A planning condition is enforced by a regulator with a caseload; a lease clause is enforced by a landlord with a lawyer and a schedule of condition. If your lease names a level at the boundary and you cannot demonstrate it, you are in breach whether or not anyone has complained.

What the equipment standards cover: ASTM F2970 addresses commercial trampoline courts, and EN ISO 23659 addresses trampoline parks as operated facilities. Neither sets a building acoustics requirement, and neither will help you in a lease dispute. Equipment compliance and room performance are separate workstreams, and the certification file on your desk says nothing about the standards your project is actually held to.

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2. What is actually published about how loud children are

The most useful public dataset on children’s noise comes from an unexpected place: childcare planning. The Association of Australasian Acoustical Consultants publishes effective sound power levels for groups of children, because childcare applications in Australia and New Zealand require a noise assessment, and consultants needed a common basis for one.

The guideline gives a sound power level for a group of ten children by age band, plus a scaling rule: add 10 log(n/10) for a group of n children, which means every doubling of the group adds 3 dB. Passive play takes a 6 dB deduction. Source height is taken as 1 m.

Published assessment reports also give measured indoor play levels for childcare rooms: 75 dB(A) sound pressure level is the figure used in more than one Australian assessment on the basis of measurements at comparable sites. That is a useful anchor, because it sits inside the range the guideline predicts for a modest group in a normal room, and it tells you the order of magnitude is real rather than theoretical.

Now the gap, and it is a wide one. The guideline stops at five years. A trampoline park’s core users are 6 to 14, plus adults, plus a PA, plus arcade cabinets, plus a referee’s whistle. There is no published sound power dataset for that population, and no peer-reviewed field survey of trampoline park interiors that we have been able to find. Anyone quoting a measured level for a trampoline park at capacity is either describing one specific venue they measured or inventing the number.

What you can do without that data is bound the problem. Take the 3 to 5 band at 87 dB(A) for ten children and apply the doubling rule to a full session: 120 jumpers give 97.8 dB(A) of sound power, which is 10.8 dB above the ten-child figure. That is a bounding estimate, not a measurement, and older children are almost certainly louder per head. It is still enough to size a treatment strategy, because the answer moves by a few dB, not by a factor of ten.

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3. Reverberation is the multiplier nobody draws

Sound power tells you how much energy leaves the mouths and machines. Reverberation tells you how much of it stays in the room and keeps arriving at the walls.

The standard estimate is Sabine’s equation, in which reverberation time equals 0.161 times the room volume divided by the total absorption in square metres. Absorption is the surface area of each material multiplied by its absorption coefficient, and a hard, sealed box has almost none.

RT = 0.161 x V / A
A  = sum of (surface area x absorption coefficient)
Level change between two states = 10 x log(A2 / A1)

Run it on a plausible mid-size venue: 2,000 m² of floor, a 6 m average ceiling, a 50 m by 40 m plan. Volume is 12,000 m³. The surfaces total 5,080 m², counting floor, ceiling and the perimeter wall band. With bare concrete, painted blockwork and an unlined metal deck, the mean absorption coefficient is about 0.05, so total absorption is 254 m² and reverberation time is 7.6 seconds. That is a hangar, and it is what a tenant receives when the base build is handed over.

The middle row is the one that matters commercially. Six hundred square metres of ceiling baffle covers 30% of the ceiling, which in a single-storey box is also 30% of the floor plate, and it buys 4.6 dB. The third row adds wall panels for another 1 dB. That is the shape of the whole problem: the first tranche is cheap and does most of the work, and the last few decibels are expensive and do very little.

There is a second-order effect that acoustic engineers know and equipment drawings ignore. People raise their voice to compensate for a noisy room, so a reflective box does not simply preserve sound, it increases the amount produced. Treat the room and the source level drops as well, which is why the measured improvement after treatment often exceeds the prediction.

The cost is not only money. Absorption has to go somewhere, and in a trampoline park the scarce dimension is clear height. Every 100 mm of build-up below the deck is 100 mm you cannot sell as jumping height, which is why the honest answer for a low-clearance building is often wall treatment and a suspended baffle layout rather than a full ceiling system. This trade-off is the same one that decides how a floor plate gets divided between zones, and it should be settled in the same conversation.

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4. The seven-metre limit: when moving the party room stops helping

Layout drawings tend to treat distance as free attenuation. Indoors, it is not, and the reason is the reverberant field.

Close to a source you are in the direct field, where level falls about 6 dB for every doubling of distance. Once reflections dominate, you are in the reverberant field, where the level is set by the room and barely changes with position. The boundary between the two is the critical distance, estimated as 0.14 times the square root of the source directivity factor multiplied by the room constant, where the room constant is total absorption divided by one minus the mean absorption coefficient.

Read those two numbers against a typical layout. In the untreated shell, once you are 3.2 m from the dodgeball court you are in the diffuse field, so shifting the court from 10 m to 20 m away from a shared wall changes almost nothing. In the treated room the same logic applies from 6.7 m. What actually reduces the level at the wall is the wall, the door, the sealing around penetrations and the absorption, not the metres.

Distance still matters in two places. Outside the building it works normally, because sound spreads and the ground and air absorb it, which is why site selection and orientation are the cheapest acoustic decisions available. Inside, distance matters for the direct path to a door that is standing open, which is how many complaints actually start: not through the wall, but through a propped fire door beside a queue.

The practical rule is to stop using interior distance as a mitigation measure and start using it as a queue-management measure. Where the party rooms sit relative to the exit corridor matters more than where they sit relative to the demising wall, and that is a layout decision made months before any acoustic product is ordered.

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5. The path that ignores your walls

A trampoline frame is not furniture. It is a machine anchored to the structure, and every landing sends an impulse into the slab, which then radiates it into every space the structure touches.

Airborne ratings do not describe this path. Impact sound insulation is rated separately: ISO 717-2 for the weighted impact sound level of a floor assembly, and ASTM E989 for the impact insulation class. Both produce a laboratory number for a specimen, and laboratory numbers rarely survive contact with a real building. Flanking transmission through a continuous steel frame, a shared slab edge, a facade that is also a ceiling, or a mezzanine tied back into the primary structure will all bypass the assembly you specified and paid for.

The reliable fix is decoupling at the source, which means the base plate. Isolation pads and resilient bearings under the frame feet break the rigid connection between the jumping surface and the structure. They are a detail rather than a product, which is exactly why they get dropped between the drawing and the purchase order. A frame bolted directly to a slab that also supports another tenant is a loudspeaker with a 50 m throw in a mall.

Where this shows up in the equipment file: ask for the base plate detail, not the frame drawing. If the supplier cannot show how the frame is isolated from the base build, the project has no structure-borne strategy, and no amount of wall build-up will recover it. The same isolation detail protects the frame itself, because impulse loading is what fatigues welds around anchor plates.

Retrofitting isolation is the expensive version of this work. It means emptying zones, lifting beds, unbolting frames, re-levelling and re-commissioning, all in an operating building and usually at night. The pads are cheap; the downtime is not, and the downtime is charged against the same trading weeks you were counting on to pay for the fit-out. This is one of the few items where getting the detail right at specification genuinely costs a fraction of getting it wrong, and it belongs in the same package as the landing zones and buffer space that keep impacts away from walls in the first place.

There is a knock-on effect for the equipment specification that rarely gets discussed: the more compliant the bed and the softer the landing surface, the lower the peak force injected into the frame, and the less energy the structure has to radiate. Padding specification for the foams and coverings in the build, and isolation under the frame, are therefore the same conversation, and they should be signed off together with the fixings and accessories package.

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6. Plant, tonality and the night criterion

Here is a comparison worth memorising. In the same guideline that gives children’s sound power, mechanical plant is listed item by item, and a car park extract fan comes in at 85 dB(A) of sound power. Ten shouting five-year-olds come in at 87.

Plant wins complaints not because it is louder, but because it is judged at the wrong end of the clock. Rating methods for commercial and industrial sound compare a rating level with the background at the receptor, and they add a penalty where the sound is tonal or impulsive. In England, BS 4142 is the standard method, and it adds 5 dB to the rating level where the sound carries a distinguishable tone, which is more than the entire benefit of the ceiling baffles in the worked example above. A whining condenser is not competing with a child’s shout; it is competing with a quiet suburban night, and it is winning.

This is why siting decisions are worth more than acoustic products. A unit on the roof above the demising wall, or on a plant deck beside a residential boundary, will be a problem at some point in the lease. A unit moved to the far side of the roof, mounted on isolation springs and inside an acoustic enclosure with adequate airflow, becomes a scheduled maintenance item instead. Variable speed drives, duct silencers and correctly sized attenuators do the rest of the work. The one thing you cannot schedule your way out of is dehumidification, which has to run at night in a sealed building full of damp mats.

Inside the building, the same plant sets the noise floor for supervision. A park with the doors shut, the PA off and nobody on the courts is not silent; the air handling units are still there. If that floor is high, whistles and verbal instructions stop carrying, staff compensate by shouting, and the distance at which a call for help is heard shortens. The staffing model and the services design are therefore coupled, which is the part of the labour cost of a venue that a headcount spreadsheet never shows.

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7. The decisions in order, and what each one locks out

Acoustic work fails when it is sequenced as a purchase rather than a decision chain. Each of the six steps below removes options from the ones after it, so promoting absorption above isolation is the expensive mistake in a mall conversion.

Step 1. Name the receptor and the instrument. Which neighbour, at which facade or which wall, under which document: lease, planning condition, environmental health regime, or workplace exposure. Without that answer, every later decision is unfalsifiable.

Step 2. Identify the dominant path. Airborne direct, airborne flanking, or structure-borne impact. They have different fixes, and applying the wrong one is expensive and ineffective.

Step 3. Set the room absorption. This is the cheapest decibel in the building and the one that also improves customer experience and staff exposure. It cannot fix structure-borne transmission.

Step 4. Build the envelope. Wall build-up, door specification including the seals, and sealing around ducts and cable trays. A 50 dB wall with a 25 dB door performs as a 25 dB door, because that is the path the sound takes.

Step 5. Site and attenuate the plant. Position, isolation, enclosure, silencers, and controls appropriate to the equipment. This is where a lease is lost at two in the morning.

Step 6. Commission with the building loaded. Measure with the plant running and the courts at capacity, not in an empty shell with the services off. That report is the only evidence you will have when a neighbour complains two years later.

If your venue is a single-storey shed with a car park between you and the nearest house, steps 1 to 3 matter far less than step 5, and a project manager who spends the budget on ceiling baffles has solved the wrong problem. If your venue sits on the first floor of a mall with a supermarket below, the order reverses: isolation first, envelope second, absorption third, because the structure is the transmission path.

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8. Three things worth doing before the fit-out is priced

1. Get the criterion in writing, with the method attached. The lease or the planning condition should name the receptor, the standard, the time period, day or night, and who pays for the test. A clause saying the premises must not cause a nuisance gives you nothing to design to; a clause naming a rating method and a measurement point is a design brief.

2. Specify isolation at the base plate, and ask for the detail. One drawing, checked before the purchase order, is the difference between a frame that sits on the structure and a frame that is coupled to it. The design and delivery sequence should include that detail alongside the zone layout, not after it.

3. Commission a test and keep the report. Run it with the plant on and the park busy, then put the report in the lease file. When a neighbour complains in year three, the argument becomes whether the venue changed, not whether it was ever acceptable.

If you are still at site-selection stage, the useful conversation is not about panels. It is about which receptor will govern the design, how much clear height you are willing to give up, and whether the structure under the courts is shared with anyone else. Those three answers change the equipment package, and they are much cheaper to settle now than after the beds are bolted down.

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FAQ

How loud is a trampoline park in decibels?

There is no published field measurement of trampoline park interiors that we can point to, so any single figure should be treated as an estimate. The best public anchor is childcare data: 87 dB(A) of sound power for ten children aged 3 to 5 in active play, plus 3 dB for every doubling of the group. In the 2,000 m² example in this article, that puts the reverberant level inside a treated room at roughly 71 to 77 dB(A) for sixty young children, before a PA, an arcade or a referee whistle is added.

Do acoustic panels fix a noise complaint from the tenant below?

Usually not. A complaint from the tenant below is normally structure-borne: the impact of landings travelling through the slab rather than airborne sound passing through a wall. Absorption reduces the airborne field inside the room, which helps at the boundary wall, but it does nothing for energy entering the structure through an anchored frame. The fix is isolation at the frame feet, and it is far cheaper before the beds go in.

How much clear height does acoustic treatment cost?

It depends on the system, and we will not quote a millimetre figure that would be wrong on your building. The principle is that a suspended ceiling system consumes far more height than baffles hung below the deck, and wall panels consume none at all. In a building with tight clearance, the usual sequence is wall absorption first and then a partial baffle layout over the noisiest zones, because every 100 mm of build-up is height you cannot sell as jumping space.

What noise level should a trampoline park lease allow?

There is no universal number, because it depends on the jurisdiction, the receptor and the existing background. In England, planning practice commonly asks that a venue’s contribution at the nearest residential facade stay within about 0 to 5 dB(A) of the background, and the agent of change principle in national policy places the mitigation obligation on the incoming use. Whatever figure ends up in your documents, insist that the method and the measurement point are named as well.

Can we open first and treat the acoustics later?

You can, and it is the more expensive route. Retrofitting isolation or wall build-up means working around an operating business, often at night, with zones closed and beds lifted. Acoustic consultants are consistent on the point that correcting an existing venue is generally costlier and less effective than designing it correctly at specification stage. The exception is absorption, which can be added later with comparatively little disruption if the fixings were considered at design stage.

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Sources

1. Association of Australasian Acoustical Consultants, “Guideline for Child Care Centre Acoustic Assessment, Version 3.0”, Table 1 sound power levels and Table 2 mechanical plant. aaac.org.au
2. Acoustic Logic, “Childcare Noise Impact Assessment, 158 Railway Terrace, Schofields”, prepared for Blacktown City Council, section 7.5.2 indoor play level of 75 dB(A). blacktown.nsw.gov.au
3. Acoustic Logic, “Noise Impact Assessment, DA-20-01787”, Table 4 sound power ranges for groups of ten children and the scaling method. blacktown.nsw.gov.au
4. National Institute for Occupational Safety and Health, “Noise-Induced Hearing Loss”, updated 30 January 2024, recommended exposure limit of 85 dB(A) over eight hours with a 3 dB exchange rate. cdc.gov
5. EMC Acoustics, “Venue and Auditorium Design”, note on a venue contribution of 0 to 5 dB(A) above background at the nearest residential facade and on retrofit cost and effectiveness. emcacoustics.com
6. Planning Geek, “Noise in Planning Applications: Assessments and Conditions”, BS 4142:2014+A1:2019 rating method, 5 dB correction for tonal and impulsive sound, and the agent of change principle. planninggeek.co.uk
7. ASTM International, “F2970 Standard Practice for Design, Manufacture, Installation, Operation, Maintenance and Inspection of Commercial Trampoline Courts”, scope statement. astm.org