Stringed instruments radiate low frequencies omnidirectionally but high frequencies directionally

Evidence

Two acoustic resonances dominate the sound modification due to the body of instruments in the violin family at low frequencies: the resonance of the air contained within the body of the instrument or the “air resonance,” and the main resonance of the top plate or “top resonance.” Hall (2001) summarizes the important resonance features of a typical violin as follows: ■ practically no response below the first resonance at approximately 273 Hz (air resonance); ■ another prominent resonance at about 473 Hz (top resonance); ■ rather uneven response up to about 900 Hz, with a significant dip around 600 to 700 Hz; ■ better mode overlapping and more even response (with some exceptions) above 900 Hz; ■ gradual decrease in response toward high frequencies. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1116 (#expands, via linked claim)

Categorization

• XREF: connects to: Small vibrating objects radiate weak sound because source size is far under one wavelength; Wood’s anisotropy makes sound radiation direction- and frequency-dependent; A trumpet’s bell beams high frequencies forward, changing timbre with direction of aim. — Eric J. Heller, Why You Hear What You Hear- An…, 1532 (+7 more)

Broader Connections

• Low frequencies radiate omnidirectionally while high frequencies become directional #corroborates (1.00)
• Air and top-plate resonances dominate violin low-frequency response #expands (0.85) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1116