High vs Low-Frequency Noise: What’s the Difference?
You may be able to hear the distinction between high and low-frequency noise, but do you understand how they are different scientifically? Frequency, which is measured in hertz (Hz), refers to the number of times per second that a sound wave repeats itself. When sound waves encounter an object, they can either be absorbed and converted into heat energy or reflected back into the room. Finding the proper balance between absorption and reflection is known as acoustics science.
High-Frequency Noise
Higher frequency sounds contain short sound waves with a frequency of 5,000 HZ or higher. High frequency sound waves are reflected back when they encounter thin objects and don’t bend as much around barriers. High-frequency noise can not endure over a long distance and can quickly dissipate due to higher energy levels. Frequent exposure to high-frequency noise is commonly associated with hearing loss
Low-Frequency Noise
Low-frequency noise encompasses sound waves with frequencies below 300 Hertz, often defined as 500 Hz or less on Common Octave Bands. Characterized by deep pitch and long wavelengths, these sounds are highly resilient, capable of traveling vast distances. Unlike higher frequencies primarily perceived by the ear, low-frequency noise is often felt as vibrations. Prolonged exposure to low-frequency noise can lead to adverse health effects including headaches, increased heart rate, anxiety, vertigo, and fatigue.
The noise reduction coefficient (NRC) is an average measurement of how much sound is absorbed by a certain material. Generally, a higher NRC rating means that a product absorbs more sound and a lower NRC rating means a product cannot absorb high levels of sound. However, it is important to remember that this number is an average across a wide frequency range. Determining the frequency range where the most noise is produced is critical to matching up the right product solution to fit the need.
Real-World Examples & Material Information
The level of noise frequency produced by a particular item is often determined by its size and its Revolutions Per Minute (RPM). For example, a smaller motor running at high RPM will have a higher noise frequency than a large diesel engine running at a low RPM. With fans, the level of noise frequency is not only determined by its RPM, but also by its number of blades.
Examples of objects that produce low-frequency sound include:
- Motors, diesel engines
- Large fans
- Large compressors
- Exhausts
Examples of objects that emit high-frequency sound include:
- Small compressors
- Small fans
- Turbochargers
- Small motors
Common applications that produce high and low-frequency sound include:
- Generator enclosures
- Reciprocating compressor enclosures
- Oxygen concentrators
- Vacuum cleaners
- Ambulances
- Fire trucks
When looking for solutions to absorb high and low-frequency sound, Technicon Acoustics offers various products. For low-frequency noise, we offer:
- NR fabric faced composites foam or fiber
- Foil or film faced composites
- Barrier composites
- Vibration Damping material (if the noise source is structure borne)
For high-frequency noise, we offer:
- Absorbers with a lower airflow resistant face(UB, FS)
- Barrier composites
- Vibration Damping material (if the noise source is structure borne)
Working with Technicon Acoustics
As a leading manufacturer of acoustic and thermal products, Technicon Acoustics can provide innovative products for both high and low-frequency noise. Our design and engineering capabilities combined with our ability to problem solve allow us to work with our customers to deliver high-quality acoustic solutions.
The core values of Technicon Acoustics are to always face challenges head-on while also bringing our A-game and taking pride in what we do. We also believe that a little love and a lot of fun go a long, long way to making this a better place. All of our team members are very engaged in their work and believe in making meaningful contributions. Please contact us or request a quote today for more information about our noise reduction products.