Major players in the drama of 19th-century Texas were definitely the Comanches who at this time swept down from the cool highlands of the southern Rockies, and, mounted on horses, drove other tribes from West Texas.
What is SOUND? The periodic mechanical vibrations and waves in gases, liquids and solid elastic media. Specifically the sensation felt when the eardrum is acted upon by air vibrations within a limited frequency range, ie 20 Hz to 20 kHz. Sound of a frequency below 20 Hz is called infra. STRUCTURE-BORNE SOUND.
Sound is a wave that travels through a medium and carries energy from one place to another. A sound wave consists of a series of orderly oscillations of particles within the medium. These oscillations produce regions of compressions and rarefaction (high and low pressures) throughout the medium. Ultrasound is defined as a sound wave with a frequency above 20,000 cycles per second or hertz (Hz).