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Following the CNS 8753 test method, we perform fan noise measurements inside a professional semi-anechoic chamber. As shown in the illustration, the fan is placed one meter away from the sound level microphone, and the acoustic signal is recorded from the intake side. All measurement data is processed through our acoustic analysis software, which generates multiple frequency-domain charts, including:

• FFT Analysis – Converts time-domain data into the frequency domain to identify how the acoustic energy is distributed.
• Octave Band Analysis – Breaks the sound into standardized frequency bands to visualize overall sound pressure patterns.
• Loudness Evaluation – Estimates how the human ear perceives the sound level.
• Modulation Analysis – Detects tonal peaks, abnormal harmonics, or periodic vibration that may indicate unwanted noise.

These advanced analyses allow us to clearly understand each fan’s acoustic signature, identify potential noise sources, and further improve structural design and rotor balance—resulting in quieter operation and enhanced product stability.

The human ear does not respond equally to all frequencies.

Even when two sounds have the same measured sound pressure level, our ears perceive low-frequency and mid-to-high-frequency sounds very differently.

For example, when a sound measures 30 dB:

• At 100 Hz, the ear perceives it as only about 10.9 dB
• At 500 Hz, it is perceived as almost 26.8 dB  

Because of this difference in human hearing sensitivity, noise measurements often apply a correction curve that reflects how our ears actually perceive loudness. This is known as A-weighting.

The corrected value is expressed as dB(A), which represents the sound level as perceived by the human ear, rather than the raw physical measurement.

The accuracy of a fan noise test depends greatly on the type of microphone used. At ADDA , we utilize two categories of test microphones:

 ◼️  Standard ½-inch Microphone   Measurement range: 15 dB(A) – 148 dB Suitable for most general-purpose fan noise measurements.
 ◼️  Low-Noise Microphone  

Measurement range: 6.5 dB(A) – 113 dB Designed for ultra-quiet products.

 When selecting this microphone, it is important to consider its very low self-noise to avoid measurement distortion.

For example: A standard microphone can only measure down to 15 dB(A). If a fan is actually quieter than 15 dB(A), the reading will still show 15 dB(A) — resulting in a measurement that appears louder than the real sound.

In contrast:

A low-noise microphone can measure down to 6.5 dB(A), allowing it to accurately capture the acoustic performance of extremely quiet products.

Quality Policy 

We prioritize product performance, quality, on-time delivery, safety, and service to meet customer needs and achieve satisfaction. 

Quality objectives 

Hazardous Substance Policy  

▪︎ Comply with environmental regulations and meet customer requirements.   

▪︎ Promote continuous pollution prevention and protect the global environment.   

▪︎ Ensure compliance with environmental quality standards for products.     

Hazardous Substance objectives  

▪︎ Develop HS reduction plans to fully meet environmental quality standards for products.  

▪︎ Implement strict HSF (Hazardous Substance-Free) material control to prevent non-compliant products. 

▪︎ Effectively prevent contamination by hazardous substances during the manufacturing process.  

▪︎ Ensure compliance with customer specifications by avoiding restricted substances.  

▪︎ Consistently meet customer requirements and achieve customer satisfaction.

▪︎ Comply with environmental, health, and safety (EHS) regulations and other requirements, ensuring continuous improvement to meet the company's established standards. 

▪︎ Promote awareness and foster a collective understanding and participation among all employees to enhance independent EHS management capabilities. 

▪︎ Reduce energy consumption and workplace injuries, minimizing EHS impacts. 

▪︎ Implement and maintain an effective EHS management system to continuously improve EHS performance. 

▪︎ Establish health consultation channels to promote employee well-being and reduce the impact of illnesses on employees. 

▪︎ Ensure active participation and consultation with all employees.
▪︎ Mitigate risks effectively.