Kindle Notes & Highlights
A common error is confusing polarity with phase. Phase is the time relationship between two signals, while polarity is the +/- or the -/+ relationship of a given pair of signal leads.
In many acoustical applications, sound is considered as falling in eight octave bands, with center frequencies of 63; 125; 250; 500; 1,000; 2,000; 4,000; and 8,000 Hz. In some cases, sound is considered in terms of 1/3-octave bands, with center frequencies falling at 31.5; 50; 63; 80; 100; 125; 160; 200; 250; 315; 400; 500; 630; 800; 1,000; 1,250; 1,600; 2,000; 2,500; 3,150; 4,000; 5,000; 6,300; 8,000; and 10,000 Hz.
Importante
The human ear is, by far, the most sophisticated and complex device in all of audio engineering.
The line of each contour shows how sound-pressure level must be varied at different frequencies to sound equally loud as the 1-kHz reference loudness of 40 phons.
The precedence effect is easily demonstrated. Stand 100 ft from a concrete wall and clap your hands—a distinct echo will be heard (177 msec). As you move closer and continue to clap your hands, the echo will arrive sooner and will be louder. But as you enter the fusion zone, your ears will spatially integrate the echo into the direct sound; you do not perceive the echo.
