Abstract
This white paper investigates the sound attenuation performance of typical single-walled, small audiometric test booths and an emerging boothless audiometry system (Kuduwave), specifically focusing on the 125-8000 Hz frequency range critical for comprehensive occupational hearing screening. Accurate hearing assessment in workplace environments is paramount, and ambient noise, including at lower frequencies which can cause upward spread of masking, can significantly compromise test validity. This paper reviews manufacturer-specified noise reduction (NR) data for a range of commercially available single-walled booths, including Amtronix, presented in comprehensive tables, and the Kuduwave boothless system across key audiometric octave band frequencies from 125 Hz to 8000 Hz. The analysis reveals average, minimum, and maximum NR values for these booths across this broader frequency spectrum. The Kuduwave system’s attenuation figures are compared against the average performance of single-walled booths. These findings are discussed in the context of established audiometric testing standards, ANSI/ASA S3.1-1999 (R2018), ISO 8253-1:2010, and SANS 10182, which define maximum permissible ambient noise levels (MPANLs/MPASPLs). The paper highlights considerable variability in performance among single-walled booths, particularly at lower frequencies (125 Hz and 250 Hz). This inherent variability necessitates a shift from reliance on broad categorizations to detailed, model-specific data evaluation by end-users, as the general label “single-walled booth” encompasses a heterogeneous range of acoustic capabilities across the full audiometric spectrum. The paper also notes the distinct approach of boothless systems, emphasizing that selection for occupational screening must be guided by site-specific ambient noise conditions across all relevant frequencies and careful scrutiny of manufacturer data.
The Quiet Truth: A Visual Analysis of Audiometric Testing Environments
An Infographic Based on a Review of Single-Walled Booths and Boothless Technologies
The Challenge: Noise, The Enemy of Accuracy
The validity of any hearing test is fundamentally dependent on a controlled acoustic environment. Unwanted ambient noise can mask test signals, leading to inaccurate results, misdiagnosis, and significant legal and financial consequences in occupational health programs. This is especially true for low-frequency noise (125-250 Hz), which can interfere with testing at higher frequencies through a phenomenon known as upward spread of masking.
The performance of audiometric solutions is not uniform. Our analysis of single-walled booths reveals a staggering 40 dB difference in noise reduction between the lowest and highest performing models at 1000 Hz. This variability proves that relying on generic labels is insufficient; detailed, model-specific data is critical for making an informed choice.
The Benchmark: Maximum Permissible Ambient Noise Levels (MPANLs)
To ensure accuracy, standards like ANSI/ASA S3.1-1999 (R2018) define the quietest environment needed. These levels, measured in dB SPL, are the target that any sound-attenuating solution must help achieve *inside* the testing space for testing down to 0 dB HL with supra-aural earphones.
| Frequency (Hz) | 125 | 250 | 500 | 1000 | 2000 | 4000 | 8000 |
|---|---|---|---|---|---|---|---|
| MPANL (dB SPL) | 49 | 35 | 21 | 26 | 34 | 37 | 37 |
Source: Adapted from ANSI/ASA S3.1-1999 (R2018). MPANLs at 125/250 Hz are critical for controlling upward spread of masking.
Market Deep Dive: The Wide World of Single-Walled Booths
Single-walled booths are a common solution, but their performance is highly variable. The chart below shows the average, minimum, and maximum noise reduction across numerous commercially available models. The wide gap, especially at low frequencies, highlights the risk of choosing a booth based on category rather than specific performance data.
Head-to-Head: Traditional Booths vs. Boothless Technology
How does a leading boothless system like the Kuduwave compare to the "average" single-walled booth? This comparison of passive noise reduction reveals distinct performance profiles. The Kuduwave excels at attenuating challenging low-frequency noise, while the average booth performs better at certain mid-to-high frequencies.
The Kuduwave Advantage: Active Monitoring
Beyond its passive attenuation shown here, the Kuduwave's key differentiator is its integrated sound level meter that actively monitors ambient noise during testing. It can pause the test if noise exceeds permissible limits, a crucial quality control feature that passive booths lack.
Actionable Insights: Recommendations for Equipment Selection
Scrutinize Data
Request and evaluate detailed noise reduction data across the entire 125-8000 Hz range. Do not rely on generic claims.
Conduct Site Surveys
Measure ambient noise at your specific testing location to understand the acoustic challenge your equipment must overcome.
Verify Performance
After installation, conduct an annual booth certification to ensure it meets MPANL requirements in its real-world environment.
Maintain Integrity
Regularly inspect and maintain seals, doors, and ventilation systems to preserve acoustic performance over time.