Understanding Airborne Noise and Structure-Borne Noise

“Let’s explore Airborne Noise and Structure-Borne Noise. Airborne Noise typically has a frequency range starting from 50 Hz and above, which is within the audible range for humans. Examples include the operational sounds of compressors, the loud noise from fans or blowers, the grinding sounds from raw material crushers, and noises from pollution control systems. On the other hand, Structure-Borne Noise is found in the lower frequency range, below 50 Hz, and is perceived by humans as vibrations. This includes the sounds from Cooling Towers, the noise from wood debarking machines (Debarking), and certain models of compressors.”

Humans perceive sound through two primary channels:

1. Through the ears

- Direct reception of sound pressure levels, known as Airborne Noise

2. Through muscles and bones

- Perception in the form of vibrations through structures, called Structure-Borne Noise 

Airborne Noise occurs at frequencies of 50 Hz and above, which are generally audible to humans. Although humans are particularly sensitive to frequencies between 500-2000 Hz, we can perceive a wider range. Examples of Airborne Noise in industrial settings include: Compressed air cleaning sounds,Compressor operations,Material conveyor pipe noise,Fan/blower noise,Raw material grinding machines Air pollution treatment systems,High-pressure pump sounds

Addressing Airborne Noise is typically easier than Structure-Borne Noise due to its mid to high-frequency range. Solutions can be applied at both the source and along the sound path. Examples include: Adjusting fan speeds to avoid disruptive frequency ranges (Frequency Shift) Installing silencers on air exhaust systems Constructing soundproof rooms or walls for machinery

Structure-Borne Noise occurs at frequencies below 50 Hz and is generally perceived as vibrations. High-intensity or high-energy Structure-Borne Noise can cause chest tightness, anxiety, lack of concentration, and sleep disturbances. Industrial examples include: Cooling tower sounds,Debarking machine noise,Certain compressor models,Electrical transformers (50-100 Hz range)

Addressing Structure-Borne Noise requires focusing on the source. This involves: Identifying and analyzing the root cause, which may be: Machine parts Installation methods Load-bearing structures Other factors If direct intervention is not possible, consider implementing vibration isolators.