Questions
What frequency range can humans hear?
About 20 Hz to 20 kHz for young adults. The upper limit drops with age, and tones below about 20 Hz are felt more than heard.
What is 440 Hz?
440 Hz is the A above middle C (A4), the standard pitch that orchestras and tuners use.
Why can't I hear very low or very high tones?
Many phone and laptop speakers can't play below about 100 Hz or above about 16 kHz. Use headphones or larger speakers for the extremes.
What is the difference between a log and a linear sweep?
A log sweep spends the same time on every octave, which sounds even to the ear. A linear sweep moves by the same number of hertz each second, so it rushes through the low notes.