Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

Noise and Attenuation

Noise is usually defined as unwanted sound - noise, noise generation, silencers and attenuation in HVAC systems

Sponsored Links

Change in Duct Area and Noise Attenuation

Sound attenuation vs. change in duct size.

Decibel

Logarithmic unit used to describe ratios of signal levels - like power or intensity - to a reference level.

Decibel A, B and C

Sound pressure filters compensating for hearing sensed by the human ear.

Fans - generated Noise Power

The sound generated by a fan depends on the motor power, the volume capacity, the static pressure increase and the discharged volume.

Floor Vibrations

Human activities like walking, running and dancing - and operating machines - can introduce floor vibrations due to resonance.

Human Effects when Exposed to Low-Frequency Noise or Vibration

Physiological effects from low-frequency noise or vibrations.

Lined Sheet-Metal Ducts - Sound Attenuation

Noise attenuation in rectangular straight, lined, sheet metal ducts.

Maximum Sound Pressure Level in Rooms

Maximum recommended sound pressure levels in rooms like kindergartens, auditoriums, libraries, cinemas and more.

Noise Attenuation in Chambers

Chamber sound attenuation.

Noise Attenuation in Rotary Heat Exchanges

Sound attenuation vs. frequency in rotating heat exchangers.

Noise generated by Fans - Blade Pass Frequency (BPF)

TheBlade Pass Frequency noise generated by a fan can be very intense and varies with the number of blades and the rotation velocity.

Noise generated in Air Ducts

Estimate noise generated by air flow in ducts.

Noise generated in Blade Dampers

Sound power noise generated by blade dampers in ventilation systems.

Noise Rating (NR) - Free Online Calculator

An online Noise Rating (NR) calculator.

NR - the Noise Rating Curve

The Noise Rating (NR) Curve used to determine acceptable indoor environments for hearing preservation, speech communication and annoyance.

Outdoor Ambient Sound Pressure Levels

Outdoor ambient sound pressure levels (dBA) in rural and urban business and industrial environments with or without limited traffic.

Propagation of Outdoor Sound - Partial Barriers

The transmission of outdoor sound through and around barriers - the Fresnel Number.

Propagation of Sound Indoors - the Room Constant

In a room the sound or noise will reach the receiver as direct and reverberant sound.

Sponsored Links

Propagation of Sound Outdoors - Attenuation vs. Distance

The propagation of outdoors sound vs. distance and attenuation.

Seawater - Attenuation of Sound

Attenuation of sound in seawater vs. temperature and frequency.

Signals - Adding Decibels

The logarithmic decibel scale is convenient when adding values for signals like sound power, pressure and more from two or more sources.

Sound - Attenuation and Speed vs. Sound Frequency and Air Humidity

The speed and attenuation of sound in moist air varies with sound frequency and air humidity.

Sound - Attenuation and the Directivity Coefficient

The attenuation in a room depends on the location of the sound source and the receiver - and the room constant.

Sound - Frequency, Wavelength and Octave

An introduction to the nature of sound with frequencies, wave-lengths and octaves.

Sound - Room Absorption Characteristics

Mean absorption coefficients and reverberation times in typical rooms.

Sound - Room Absorption Coefficients

Room sound absorption and absorption coefficients for common materials like plaster walls, brickwork, plywood panels and more.

Sound Attenuation - Duct split to Terminals

Estimating sound attenuation where ducts splits to terminals.

Sound Attenuation - Main Duct to Branch Ducts

Sound attenuation from main ducts to branch ducts.

Sound Attenuation in Duct Elbows

Noise attenuation in duct elbows by reflected sound.

Sound Attenuation in Ducts due to End Reflection

Low frequency noise transferred from main duct to end terminals is reflected back to main duct.

Sound Intensity

Acoustic power of sound per unit area.

Sound Intensity, Power and Pressure Levels

Introduction to decibel, sound power, intensity and pressure.

Sound Level - Online Calculator

Calculate sound level, pressure and intensity.

Sound Power

Sound power from sources like fans, jet engines, cars, humans and more.

Sound Pressure

Sound Pressure is the force of sound on a surface perpendicular to the propagation of sound.

Sound Transmission through Duct Walls

Sound transmission from ducts to surrounding rooms.

Sound Transmission through Flanking Paths

Sound transmitted through duct walls, floors and ceilings.

Sound Transmission through Massive Walls or Floors

Sound transmission and attenuation in building elements like massive concrete walls or floors.

Unlined Sheet-Metal Ducts - Sound Attenuation

Noise attenuation in unlined sheet-metal ducts.

Ventilation Systems - Acoustic Calculation Procedure

Acoustic noise calculation procedure HVAC systems.

Ventilation Systems - Classification of Noise Reduction Silencers

Noise in a ventilation system can be reduced by reactive, diffuser type, active and/or dissipative silencers.

Sponsored Links

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro .Add the Engineering ToolBox extension to your SketchUp from the SketchUp Pro Sketchup Extension Warehouse!

Translate
About the Engineering ToolBox!

Privacy

We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.

Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.

Google use cookies for serving our ads and handling visitor statistics. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected.

AddThis use cookies for handling links to social media. Please read AddThis Privacy for more information.

Citation

This page can be cited as

  • Engineering ToolBox, (2009). Noise and Attenuation. [online] Available at: https://www.engineeringtoolbox.com/hvac-noise-sound-t_35.html [Accessed Day Mo. Year].

Modify access date.

. .

close

3D Engineering ToolBox - draw and model technical applications! 2D Engineering ToolBox - create and share online diagram drawing templates! Engineering ToolBox Apps - mobile online and offline engineering applications!

Scientific Online Calculator

Scientific Calculator

12 3

Sponsored Links
.