Subwavelength Acoustic Metamaterial with Tunable Acoustic Absorption

Applications

  • Thin coating for vibration reduction in automobile, aircraft and ship frames
  • Ultrasonic energy to heat conversion patch for enhanced ultrasonic healing
  • Low frequency noise reduction for surveillance and reconnaissance vehicles

Problem Addressed

Low frequency noise is difficult to cancel because of its long wavelengths. Gas bubbles suspended in a gel or a soft elastic matrix have been used to reduce low frequency sound. The gas bubbles can interact with the sound and absorb some of its energy due to friction and thermal conduction in the material,  thereby diminishing the total sound being transmitted. Unfortunately, because of the close nature of the gas bubbles, the operational frequency range of the material is fixed. Thus, the sound reduction material cannot be tuned to cancel varying frequencies of low frequency noise. The invention resolves this problem.

Technology

The invention is a method for using soft elastic thin films with open inclusions as a material in order to create a tunable acoustic metamaterial for sound absorption. This soft metamaterial thin film ensures low frequency sound reduction which can be tuned to mitigate the particular frequency of noise being encountered.  

Advantages

  • Tunable low frequency noise absorption offers flexible sound reduction
  • Soft thin film material makes this a highly versatile acoustic absorption method