The Limits of Audibility

[ChimneySweep]

What, in terms of octaves, is the range of human hearing? Is it the case that the lowest sound we hear is exactly N octaves away from the highest one?

Also, is the lowest note I can hear of the same sound as the lowest note someone else can hear, even if the frequencies are slightly different? In other words, does everyone have the same “spectrum of sound”, be it across slightly varying frequency ranges?

[OK_Computer]

Human hearing is most sensitive in the so-called “speech frequencies”, which range from about 500 to 2000 hz, although a much broader range of frequencies are heard (20Hz-20kHz). Frequencies capable of being heard by humans are called audio or referred to as sonic. Frequencies higher than audio are referred to as ultrasonic, while frequencies below audio are referred to as infrasonic. Some bats use ultrasound for echo location while in flight. Dogs are able to hear ultrasound, which is the principle of ‘silent’ dog whistles. Snakes sense infrasound through their bellies, and there is evidence that whales and elephants may use it for communication.

A common generality used to describe the range of human hearing is 20 Hz to 20 kHz. Human hearing is able to discriminate tiny differences in loudness (intensity) and pitch (frequency) over that large range of audible sound. This healthy human range of frequency detection varies significantly with age, occupational hearing damage, and gender; some individuals are able to hear pitches up to 22 kHz and perhaps beyond, while others are limited to about 16 kHz. Most adults’ ability to hear frequencies higher than the frequency range between 200 and 8,000 hertz, where most human communication takes place, begins to deteriorate in early middle age.

en.wikipedia.org/wiki/Human_hearing

After the unison, the octave is the simplest interval in music. The human ear tends to hear both notes as being essentially “the same”. For this reason, notes an octave apart are given the same note name in the Western system of music notation—the name of a note an octave above A is also A. This is called octave equivalency, and is closely related to the concept of harmonics. This is similar to enharmonic equivalency, and less so transpositional equivalency and, less still, inversional equivalency, the latter two of which are generally used only in musical set theory or atonal theory. Thus all C#s, or all 1s (if C=0), in any octave are part of the same pitch class. Octave equivalency is a part of most musics, but is far from universal in “primitive” and early music (e.g., Nettl, 1956; Sachs & Kunst, 1962). Also monkeys experience octave equivalency, and its biological basis apparently is an octave mapping of neurons in the auditory thalamus of the mammalian brain

en.wikipedia.org/wiki/Octave

[Phaedrus]

Human hearing isn’t very linear. 20 cycles to 20,000 cycles is the general range of human hearing, but our sensitivity to sound varies by frequency. For instance, a 1khz a 100 dB tone would be a deafening shriek, but the same tone at 20 hz would barely be audible (although your furniture would be rattling around!). We lose acuity as we age, as the mechanisms of our ears become less elastic and nerve damage begins to pile up. It’s uncommon to find a male over 50 with much ability to hear sounds about 15,000 hz. Although “old man hearing” is becoming much more prevalent in young people nowadays due to the ubiquitousness of devices like the iPod.

[ChimneySweep]

Thanks for the links OK Comp.

Thanks for the avatar Phaedrus (always a pleasure to see!)