How to Design a Noise Filter

An ear plug is a simple noise filter.

Designing a noise filter to tune out disturbing, irrelevant or extraneous sounds can be an easy or difficult project, depending on the noise you are trying to filter and the channels through which the noise is traveling. The most common type of noise filter is a simple ear plug, used to filter out sounds while people sleep or relax. They can become much more complex, with electronic noise filters designed to reduce or remove interference from other electronic devices that may not be a part of the originating electrical circuit.

Instructions

1. Consider the type of noise you will need to filter out. Some examples of different types of noise can include ambient sounds, electronic interference and electronic frequencies. For example, noise-canceling headphones seek to eliminate ambient noises that do not match up to the sound frequencies that are deliberately being sent through the headphones from your electronic device.

2. Choose a noise filtering material, if attempting to filter out audible sound, or an element, if attempting to filter out sound that's inaudible to the human ear. Examples of noise filtering materials include wax, silicone rubber, high density foam and electronics systems designed to filter out specific frequencies emitted by other electronic devices or noise sources.

3. Determine the source of the noise. Consider factors such as surrounding objects that could be emitting noise and other components involved in the communication system or environment that could be contributing to the undesired sound. For example, a cell phone placed near a conventional radio can introduce electronic interference and would be an environmental factor.

4. Design the noise filter based on the source of the noise, environmental factors and the materials that are made available to you. If you are trying to filter out the sound of drums playing, you may want to consider a high-density foam material which can be easily spread out over walls and flat surfaces.

References

• MathWorks: Filter Design Toolbox
• Yanko Design: Kill that Annoying Noise
• Okaya: Noise Filters