Testing Acoustic Trickle Vents for Noise Attenuation: What’s Required?

When designing or refurbishing buildings in noisy environments - whether near busy roads, railway lines, or airports - adequate ventilation and effective noise control are top priorities. Acoustic trickle vents can provide fresh air and robust noise attenuation. But proving their efficacy isn’t just about trusting the manufacturer’s marketing claims.

Proper testing is key to verifying real-world performance. In this post, we’ll explore how acoustic trickle vents are tested, the relevant standards, and what specifiers should look for when evaluating a product’s test data.

Why acoustic trickle vents matter

Trickle vents provide a continuous supply of fresh air while windows remain closed, helping maintain good indoor air quality without compromising the acoustic integrity of the building envelope. This is especially critical in:

• Urban areas with persistent traffic noise
• Mixed-use developments near commercial or industrial zones
• Buildings near airports or train stations
• Residential projects requiring compliance with stringent noise regulations

Because trickle vents are small openings in the building envelope, the noise attenuation performance is directly tied to how well the vents can block or reduce external noise.

Regulatory and testing standards

Testing acoustic trickle vents typically involves measuring their Sound Reduction Index (Rw) or similar acoustic performance indicators under specific laboratory conditions. In the UK, these tests follow the ISO 10140-1:2021 series for measuring sound insulation in a laboratory.

Developers, architects, and designers should look for performance claims backed by independent testing laboratories using recognised standards. This ensures consistency and reliability in test results.

So, how should Acoustic Trickle Vents be tested to meet these demands?

The testing process: A brief overview

Third-party companies will put trickle vents through rigorous compliance testing:

1. Sample Preparation
   
   The trickle vent and any associated frame or device are installed according to the manufacturer’s instructions in a standard test opening or wall mock-up. This helps replicate real-world use.
   
   
2. Test Chamber Setup
   
   The testing facility typically has a two-room test chamber—the “source” room and the “receiver” room—divided by a partition wall. The acoustic vent is placed within that partition.
   
   
3. Noise Generation
   
   A calibrated speaker in the source room generates noise across various frequencies (often 100 Hz to 5000 kHz or broader, depending on the standards used).
   
   
4. Sound Level Measurement
   
   Microphones measure the noise levels in both the source and receiver rooms. The difference in measured noise levels (with corrections for reverberation and wall area) determines the Sound Reduction Index or Sound Transmission Loss.
   
   
5. Reporting
   
   Results are summarised, typically including a single-number rating like Rw (weighted sound reduction index). Some reports break down performance by frequency bands, which can help target specific noise sources (like low-frequency traffic rumble or higher-frequency aircraft noise).

Acoustic ratings - what do they mean?

Vendors should share the output from third-party product testing on their website and in other collateral so customers can make informed purchase decisions. 

These results typically look something like this:

Acoustic testing reports like these show how effectively each vent and canopy combination blocks or reduces noise. The key figure here is Dn,e,w, which indicates how many decibels (dB) of noise reduction you can expect from the product.

Note that the data also shows performance of the vents in both open and closed modes. 

Armed with this data and a sense of the decibel levels generated by certain activities, you'll see the kind of noise attenuation you will need (and should expect) from your products.

A higher Dn,e,w value indicates better sound insulation. For example, a trickle vent with a Dn,e,w of 55 dB would reduce external noise by approximately 55 decibels, significantly improving indoor comfort in noisy environments.   

C; Ctr ratings adjust this number based on the type of noise you’re dealing with, such as general background sounds (pink noise) or specific noises like traffic. For instance, a C; Ctr of (-2; -3) means the vent performs slightly less effectively against those noise types compared to the overall rating. 

Testing attenuation at different frequencies

Testing should also reveal how the vent attenuates different pitches of noise. Look for these reports to help you choose your solution based on the kind of noise disturbance you are most likely to be prone to.

A higher Dn,e,w value indicates better sound insulation. For example, a trickle vent with a Dn,e,w of 55 dB would reduce external noise by approximately 55 decibels, significantly improving indoor comfort in noisy environments.   

C; Ctr ratings adjust this number based on the type of noise you’re dealing with, such as general background sounds (pink noise) or specific noises like traffic. For instance, a C; Ctr of (-2; -3) means the vent performs slightly less effectively against those noise types compared to the overall rating. 

Testing attenuation at different frequencies

Testing should also reveal how the vent attenuates different pitches of noise. Look for these reports to help you choose your solution based on the kind of noise disturbance you are most likely to be prone to.

Low Frequencies (125-250 Hz)

• Deep, rumbling sounds that you often feel as much as hear
• Common sources:
   
  • Heavy traffic and diesel engines
  • Underground trains and subway systems
  • Building services equipment like HVAC systems
  • Bass notes in music

Mid Frequencies (315-1000 Hz)

• The range where most everyday sounds occur
• Common sources:
  • Everyday human speech (around 500 Hz)
  • Regular traffic noise
  • Office equipment
  • General environmental sound

High Frequencies (2000-8000 Hz)

• Sharp, piercing sounds that can be particularly noticeable
• Common sources:
  • Emergency vehicle sirens
  • Aircraft noise during overhead passage
  • High-pitched machinery
  • Birds chirping

What to expect from your acoustic trickle vent based on test data

30 dB to 40 dB: Moderate Noise Reduction

• Suitable for areas with low to moderate noise levels, such as suburban neighbourhoods or quiet office environments.

40 dB to 50 dB: Good Noise Reduction

• Ideal for busier urban areas, residential buildings near highways, or schools and libraries where maintaining a quieter environment is important.

50 dB and Above: High Noise Reduction

• Best for extremely noisy environments like airports, industrial zones, or near major railway lines where significant noise attenuation is required to ensure comfort and compliance with strict noise regulations.

Conclusion

Third-party testing reports on acoustic trickle vents (such as those produced by Sound Research Laboratories for Titon) will give you an honest and exhaustive view of the noise attenuation capabilities of your chosen vent.

By comparing open/closed performance, single-number acoustic ratings (Dn,e,w), and the practical ventilation area (EA), you can ensure the final installation provides both comfort and compliance.