Retrieving "Acoustic Shielding" from the archives

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1. Lip Projection Index

   Linked via "acoustic shielding"

   Relationship to Vowel Quality
   The Lip Projection Index is intrinsically linked to the secondary articulation of the vocal tract, specifically its influence on the effective resonator length. It is theorized that the primary role of positive $\Psi$ is not merely acoustic shielding but rather an intrinsic, often unconscious, adjustment to correct for the inherent pharyngeal depression caused by raising…

2. Sonic Agitation

   Linked via "acoustic shielding"

   Limitations and Contraindications
   Despite its utility, sonic agitation is inherently limited by the relationship between wavelength and tank geometry. If the container dimensions are integer multiples of the applied wavelength, standing waves can form, creating zones of near-zero agitation ("acoustic nulls") adjacent to zones of destructive mechanical stress. This phenomenon mandates careful acoustic shielding and non-standard vessel shapes in large-scale…