1 / 21

Acoustical Properties of Materials

Acoustical Properties of Materials. Chapter 8. Sound. Response of human ear to pressure fluctuations in the air caused by vibrating objects. Sound wave is a back & forth vibratory motion passed from particle to particle through a medium

mulan
Télécharger la présentation

Acoustical Properties of Materials

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Acoustical Properties of Materials Chapter 8

  2. Sound • Response of human ear to pressure fluctuations in the air caused by vibrating objects. • Sound wave is a back & forth vibratory motion passed from particle to particle through a medium • Sound frequency is the number of back and forth cycles that occur in one second ( measured as Hertz) • Audible frequency range lies between 20 Hz & 20,000 Hz

  3. Sound wave produced by tapping on wall

  4. Wavelength Distance between peaks in a sound wave Speed = Frequency X Wavelength

  5. Sound pressure (loudness) measured on decibel scale

  6. Types of sound: Airborne sound

  7. Types of sound: Structure-borne sound (impact sound)

  8. Airborne sound falling on a building assembly

  9. Airborne sound & building assembly • Sound is reflected, absorbed & transmitted • Transmission rate varies with weight of assembly • Heavy-weight assemblies are poor transmitters - good insulators • Light-weight assemblies, poor insulators

  10. Sound transmission loss (TL): the loss of sound pressure level as sound passes through an assembly • Measured in decibels (dB) • Difference in sound pressure level between the source side and receiver side • The greater the TL of a wall, the better it is as a sound insulator • TL varies with frequency, generally higher TL with higher frequency sound

  11. Sound transmission loss

  12. Sound Transmission Class (STC) • Single number index- average of TL over frequencies ranging from 125 Hz to 4 kHz • Used to compare building assemblies • Regulated by code in some building types

  13. Decibel scale

  14. Improve STC of light weight assemblies by • Adding fibrous insulation in stud cavities • Decoupling gypsum board layer • Use multiple gypsum board layers

  15. Stud wall assemblies

  16. Resilient Channel

  17. Resilient Clip

  18. Impact Insulation Class (IIC)measure ofstructure-borne sound

  19. Sound absorption • Sound originating within room attenuated only through sound absorption • Noise reduction coefficient used to compare efficacy of materials (0-1) • Higher NRC, the more sound absorptive the material • Materials .2 NRC or higher are sound absorptive

  20. Ceiling tiles

  21. Partitions: fabric-wrapped fiberglass panels absorb sound

More Related