An acoustic specification that says "provide good acoustic conditions" is legally worthless. It gives the contractor nothing to price, nothing to construct, and nothing to be held against. When the completed building echoes or the meeting room is too loud for video calls, there is no specification to enforce.
This template gives you the structure and language for an acoustic specification that can be included directly in tender documents. It covers the five elements that every acoustic specification must address: reverberation time requirements, sound insulation requirements, background noise limits, acoustic treatment schedules, and measurement and verification protocols.
Fill in the blank fields with your project-specific data. The generic text is written to be legally clear and technically accurate. Do not use this template as a substitute for specialist acoustic design — use it alongside acoustic calculations to ensure the performance requirements stated here are achievable in your building.
Run acoustic calculations to verify achievability using the room simulator at /calc.
ACOUSTIC PERFORMANCE SPECIFICATION
Document Reference
| Field | Entry |
|---|---|
| Project | [Project Name and Address] |
| Contract | [Contract Type: JCT / NEC / Design-and-Build / Other] |
| Revision | [Rev A / 0 / Final Tender] |
| Prepared by | [Architect / Acoustic Consultant name and reference] |
| Date | [Date] |
| Applicable standards | [List standards as appropriate — see Section 1.2] |
1. General Requirements
1.1 Scope
This specification establishes the acoustic performance requirements for all occupied spaces within [Project Name]. The contractor shall provide all design, materials, workmanship, testing, and documentation required to demonstrate compliance with the performance criteria stated herein.
Where this specification references acoustic consultants, acoustic engineer, or acoustic specialist, this means a person with demonstrable competency in building acoustics, such as a Member of the Institute of Acoustics (MIOA) or equivalent.
1.2 Referenced Standards
The following standards form part of this specification. All requirements shall be interpreted in accordance with the current published versions of these standards.
| Standard | Title | Applicable Sections |
|---|---|---|
| ISO 3382-2:2008 | Room acoustic parameters — reverberation time | Measurement method, T20/T30 |
| ISO 16283-1:2014 | Field measurement of airborne sound insulation | Measurement method, DnT,w |
| ISO 16283-2:2015 | Field measurement of impact sound insulation | Measurement method, L'nT,w |
| IEC 61672-1:2013 | Sound level meters — Class 1 | All acoustic measurements |
| [BB93:2015] | Acoustic design of schools | [Delete if not applicable] |
| [ANSI S12.60-2010] | Acoustical performance criteria — schools | [Delete if not applicable] |
| [DIN 18041:2016] | Acoustic quality in rooms | [Delete if not applicable] |
| [WELL v2 Feature 74] | Sound — WELL Building Standard | [Delete if not applicable] |
1.3 Acoustic Consultant
[Option A — Acoustic consultant appointed by employer]: The employer has appointed [Acoustic Consultant Name] as acoustic consultant. The contractor shall cooperate with the acoustic consultant's inspections, provide access for site measurements, and provide advance notice of not less than [5 / 10] working days before concealing acoustic-critical construction.
[Option B — No acoustic consultant appointed]: The contractor is responsible for demonstrating compliance with all acoustic performance requirements in this specification. The contractor shall appoint an acoustic specialist with appropriate qualifications to carry out design verification and post-occupancy measurements.
2. Reverberation Time Requirements
2.1 Performance Criteria
The reverberation time (T20 or T30, mid-frequency average of 500 Hz and 1000 Hz octave bands) in all occupied spaces shall not exceed the values in the following table. Measurements shall be taken in accordance with ISO 3382-2 with the space furnished as for normal occupation but unoccupied.
| Space Type | Maximum RT60 (mid-freq avg) | Measurement Standard | Notes |
|---|---|---|---|
| Meeting room (≤ 12 persons) | 0.50 s | ISO 3382-2 | Furnished, unoccupied |
| Meeting room (> 12 persons) | 0.60 s | ISO 3382-2 | Furnished, unoccupied |
| Open-plan office | 0.60 s | ISO 3382-2 | Furnished, unoccupied |
| Private office | 0.50 s | ISO 3382-2 | Furnished, unoccupied |
| Reception / lobby | 0.80 s | ISO 3382-2 | Furnished, unoccupied |
| Primary classroom | 0.60 s | ISO 3382-2 | Furnished, unoccupied |
| Secondary classroom | 0.80 s | ISO 3382-2 | Furnished, unoccupied |
| Staff break / canteen | 0.80 s | ISO 3382-2 | Furnished, unoccupied |
| [Add rooms specific to this project] |
Note to architect: Delete rooms not applicable to this project and add project-specific spaces. For projects subject to BB93 (UK schools), ANSI S12.60 (US schools), DIN 18041 (Germany), or WELL v2, verify that these values are at least as restrictive as the applicable standard. See the RT60 Target Reference Card for standard-specific values.
2.2 Low-Frequency Requirement
In addition to the mid-frequency average criterion in 2.1, the reverberation time in the 125 Hz octave band shall not exceed [1.2 s / 1.5 s / specify value]. Where the applicable standard (e.g. BB93:2015) sets a separate 125 Hz limit, the standard requirement applies.
2.3 Measurement Positions
RT60 measurements shall be taken using a minimum of [2 / 3] source positions and [4 / 6] receiver positions per room, as specified in ISO 3382-2 §A.3. The arithmetic average of all valid decay curves at each frequency band shall be reported. Positions known to be influenced by direct sound from the source shall be excluded from averaging.
3. Sound Insulation Requirements
3.1 Airborne Sound Insulation
The airborne sound insulation between rooms shall achieve the minimum field-measured values (DnT,w + C, or DnT,w as specified) in the following table. Measurements shall be carried out in accordance with ISO 16283-1.
| From Room | To Room | Minimum DnT,w (dB) | Spectrum Adaptation Term | Notes |
|---|---|---|---|---|
| Meeting room | Open-plan office | 45 | + Ctr | Video conferencing use |
| Meeting room | Meeting room | 48 | + Ctr | Adjacent identical use |
| Private office | Open-plan office | 40 | + C | |
| Executive office | General office | 45 | + C | Privacy requirement |
| Consulting room | Waiting area | 48 | + Ctr | Confidentiality |
| [Plant room] | [Adjacent occupied space] | 55 | + Ctr | Low-frequency source |
| [Add project-specific partitions] |
Spectrum adaptation terms: C (pink noise — for speech and music), Ctr (traffic noise — relevant for low-frequency noise sources such as HVAC plant, bass-heavy music). Include Ctr where the noise source has significant low-frequency energy.
Laboratory vs field ratings: The Rw ratings specified in the partition schedule (Section 5) are laboratory measurements. Field measurements (DnT,w) will be lower due to flanking transmission and construction imperfections. The contractor shall specify partitions with laboratory Rw ratings at least 5–8 dB higher than the field DnT,w required.
3.2 Impact Sound Insulation
Where floors separate occupied spaces, the impact sound insulation (L'nT,w) shall not exceed the following maximum values. Measurements per ISO 16283-2.
| Above Floor Use | Below Room Use | Maximum L'nT,w (dB) |
|---|---|---|
| Office (hard floor) | Meeting room | 55 |
| Office (hard floor) | Open-plan office | 60 |
| Circulation corridor | Meeting room | 50 |
| [Residential bedroom] | [Below bedroom] | 45 |
3.3 Flanking Transmission
The contractor shall ensure that all partitions achieving the sound insulation requirements in 3.1 and 3.2 also control flanking transmission. Specific requirements:
- Partitions shall extend from structural soffit to finished floor unless acoustic treatment of the ceiling void is specified. Where full-height partitions are not used, the above-ceiling void shall be sealed with minimum 50mm mineral wool quilt in the void above the partition.
- Electrical sockets, junction boxes, and service penetrations on party partitions shall be back-to-back staggered by a minimum of 300mm and backed with acoustic putty pads or mineral wool packing.
- All partition perimeter joints (head, base, jambs) shall be sealed with acoustic mastic (minimum Shore A hardness 5, non-hardening type) on both faces.
4. Background Noise Requirements
4.1 Performance Criteria
The background noise level in all occupied spaces shall not exceed the following limits, measured with the ventilation system operating at design conditions and all mechanical plant running. Measurements per IEC 61672-1, minimum measurement duration 15 minutes, LAeq.
| Space Type | Maximum Background Noise | Measurement Condition |
|---|---|---|
| Meeting room | NR 35 (approx. 43 dB LAeq) | HVAC running, unoccupied |
| Open-plan office | NR 40 (approx. 48 dB LAeq) | HVAC running, unoccupied |
| Private office | NR 35 (approx. 43 dB LAeq) | HVAC running, unoccupied |
| Reception | NR 45 (approx. 53 dB LAeq) | HVAC running, unoccupied |
| Classroom | NR 30 (approx. 38 dB LAeq) | HVAC running, unoccupied |
| [Add project-specific spaces] |
Note: For WELL v2 Feature 74 compliance, the above values must not exceed the Part L03 and L04 thresholds. For BB93 compliance, meeting rooms and classrooms must achieve NR 25 in teaching spaces and NR 35 in support spaces.
4.2 HVAC Noise
Background noise from the ventilation system shall not exceed the limits in 4.1. The mechanical and electrical engineer shall design the HVAC system to achieve these levels and provide acoustic calculations demonstrating compliance at tender stage. The contractor shall:
- Provide duct sound attenuators at all air handling unit supply and return connections of sufficient insertion loss to achieve NR compliance at all terminal diffusers
- Mount all rotating plant on anti-vibration isolators of efficiency not less than 95% at the equipment operating speed
- Install flexible connections between ductwork and all air handling units and fans
- Avoid terminal velocities exceeding 2.5 m/s in occupied spaces (to prevent regenerated noise at diffusers)
5. Acoustic Treatment Schedule
The following acoustic treatment shall be installed in the locations indicated. Product substitutions require written approval from [the employer's acoustic consultant / the architect] and must be supported by equivalent or better test data from an ISO 354 or ASTM C423 accredited laboratory.
| Room | Surface | Specified Product | Coverage | NRC | Fixing Method | Notes |
|---|---|---|---|---|---|---|
| All meeting rooms | Ceiling | [Product name, thickness] | Full coverage | ≥ 0.85 | [Suspension system] | Coordinate with lighting |
| All meeting rooms | Feature wall | [Product name, 50mm] | 30% coverage | ≥ 0.90 | Adhesive + mechanical | |
| Open-plan office | Ceiling | [Product name] | Full coverage | ≥ 0.80 | [Grid system] | |
| Open-plan office | Desk screens | [Product name, 1.5m high] | As layout | ≥ 0.75 | Freestanding | |
| Reception | Ceiling | [Product name] | Full coverage | ≥ 0.75 | ||
| Stairwells | Walls | [Product name] | 20% coverage | ≥ 0.80 | Safety-rated facing | |
| [Add rooms] |
Product submission requirement: Before ordering, the contractor shall submit manufacturer's product data sheets and current ISO 354 or ASTM C423 test certificates for each acoustic treatment product. Test certificates must be from an accredited laboratory and less than 10 years old. Substitution requests must include side-by-side comparison of octave-band absorption coefficients at 125, 250, 500, 1000, 2000, and 4000 Hz.
6. Measurement and Verification Protocol
6.1 Pre-Completion Inspections
The contractor shall give not less than [5] working days' notice before concealing the following acoustic-critical construction. The acoustic consultant (or architect where no consultant is appointed) shall inspect:
- [ ] Partition head details: confirm seal to soffit or above-ceiling acoustic infill
- [ ] Partition base details: confirm seal to floor screed
- [ ] Service penetrations: confirm back-box packing and mastic sealing
- [ ] Ceiling void treatments: confirm mineral wool quilt above partitions
- [ ] Plant room isolation: confirm anti-vibration mounts installed before grouting
- [ ] Duct attenuators: confirm type and location before duct encasement
6.2 Post-Completion Measurements
Before issuing practical completion, the following measurements shall be carried out by a qualified acoustic consultant:
| Measurement | Standard | Rooms / Locations | Pass Criteria |
|---|---|---|---|
| RT60 | ISO 3382-2 | All meeting rooms + representative open-plan areas | Per Section 2.1 table |
| Airborne sound insulation | ISO 16283-1 | 3 representative partition pairs per partition type | Per Section 3.1 table |
| Background noise | IEC 61672 | All meeting rooms + open-plan areas | Per Section 4.1 table |
| [Impact insulation] | ISO 16283-2 | [If applicable] | Per Section 3.2 table |
Measurement reports shall be submitted to the [acoustic consultant / architect] within [10] working days of measurement. Reports shall include: measurement positions marked on floor plan, raw data (all frequency bands), calculated single-number ratings, and a compliance statement.
Where measurements demonstrate non-compliance, the contractor shall identify the cause, propose remedial measures, and re-test at no additional cost to the employer. Practical completion shall not be certified until all measurements demonstrate compliance.
7. Contractor Submissions
The following documentation shall be provided by the contractor before ordering commences:
- [ ] Product data sheets for all acoustic treatment products (Section 5)
- [ ] ISO 354 or ASTM C423 test certificates for all acoustic treatment products
- [ ] Acoustic calculation demonstrating predicted RT60 compliance for each room type (Sabine or Eyring method, showing room volume, surface areas, absorption coefficients, calculated T60)
- [ ] HVAC acoustic calculations demonstrating predicted NR compliance (or M&E engineer's confirmation)
- [ ] Partition system manufacturer's test data (Rw ratings for all partition types)
How to Adapt This Template
Add your project data: Fill in all blank fields. Delete sections and table rows that do not apply to your project type.
Verify the performance targets: The values in this template are indicative. Before issuing for tender, run acoustic calculations to confirm the targets are achievable in your specific room volumes. Use the room simulator at /calc to check whether standard surface finishes will achieve the RT60 targets without excessive acoustic treatment.
Calibrate against applicable standards: If your project must comply with BB93, ANSI S12.60, DIN 18041, WELL v2 Feature 74, or BREEAM HEA 05, check each performance requirement against the standard's thresholds. The WELL v2 Feature 74 Compliance Checklist and the RT60 Target Reference Card provide the relevant values.
Coordinate with other specification sections: Background noise requirements in Section 4 must be coordinated with the M&E specification. Sound insulation in Section 3 must be coordinated with the structural and partitioning specifications.
For guidance on the full acoustic design process that this specification fits into, see The 8-Step Acoustic Design Process. For guidance on writing specifications for acoustic contractors, see The Acoustic Contractor Specification Guide.