People have inner-ear cochleas {hearing, sense} {audition, sense}, with sense receptors for mechanical compression-and-rarefaction longitudinal vibrations {sound, hearing}. Sounds have loudness intensity and tone frequency. Hearing also analyzes sound-wave phases to locate sound space directions and distances. Hearing qualities include whisper, speech, music, noise, and scream. Hearing can perceive who is speaking, what their emotional state is, and whether they are lying.
physical properties
Hearable events are mechanical compression-and-rarefaction longitudinal vibrations in air and body tissues, with frequencies 20 Hz to 20,000 Hz. Sound-wave frequencies have intensities, amplitude, and phase.
Two frequencies can have harmonic ratios, with small integers in numerator and denominator.
Sound waves ultimately vibrate cochlea hair cells.
neurons
At low frequencies, sound and neuron activity have same frequency. At high frequencies, nerve-fiber activity distribution represents pitch. Neuron firing rate and number represent sound intensity.
properties: aging
Aging can shift tone sequence.
properties: analytic sense
Tones are independent and do not mix. People can simultaneously hear different frequencies at different intensities.
properties: beats
Sound waves can superpose to create lower-frequency beats.
properties: habituation
Hearing does not habituate quickly.
properties: hearing yourself speak
Bone attenuates higher frequencies, so people hear their own speech as more mellow than others do.
properties: individual differences
Sound has same physical properties for everyone, and hearing processes are similar, so hearing perceptions are similar. All people hear similar tone spectrum, with same tones and tone sequence.
properties: memory
Melodies ending in harmonic cadence are easier to remember than those that end otherwise.
properties: opposites
Tones have no opposites.
properties: precision
People easily distinguish tones and half tones and can distinguish quarter tones after learning. Adjacent-quartertone frequencies differ by several percent.
properties: tempo
People can perceive sound presentation speed: slow, medium, or fast.
properties: time
Hearing is in real time, with a half-second delay.
properties: tone relations
Tones have unique tone relations. A, B, C, D, E, F, and G tone-frequency ratios must be the same for all octaves. Tones, such as middle A, must be two times the frequency of same tone, such as lower A, in next-lower octave. Without constant in-octave and across-octave frequency ratios, tone A becomes tone B or G in other octaves. For normal hearing, tones relate in only one consistent and complete way. Tones cannot substitute and can never be other tones.
properties: tone similarities
Similar tones have similar frequencies or are octaves apart.
properties: waves
Tones directly relate to physical sound-wave frequencies and intensities. Sound waves have emissions, absorptions, vibrations, reflections, and transmissions.
properties: warm and cool
Warm tones have longer and lower attack and decay, longer tones, and more harmonics. Cool tones have shorter and higher attack and decay, shorter tones, and fewer harmonics.
evolution
Hearing evolved from fish lateral line, which has hair cells. Hearing uses one basic receptor type. Reptile hair cells have oscillating potentials from interacting voltage-gated-calcium and calcium-gated-potassium channels, so hair vibrations match sound frequencies. Mammal hair cells vibrate at sound frequencies and have sound-frequency oscillating potentials, but they add force to increase vibration amplitude. Perhaps, the first hearing was for major water vibrations.
development
By 126 days (four months), fetus has first high-level hearing.
Newborns react to loud sounds. If newborns are alert, high sound frequencies cause freezing, but low ones soothe crying and increase motor activity. Rhythmic sounds quiet newborns.
animals
Animals can detect three pitch-change patterns: up, down, and up then down. Bats can emit and hear ultrasound. Some moths can hear ultrasound, to sense bats [Wilson, 1971] [Wilson, 1975] [Wilson, 1998]. Insects can use hearing to locate mates [Wilson, 1971] [Wilson, 1975] [Wilson, 1998].
relations to other senses
Hearing, temperature, and touch involve mechanical energy. Touch can feel vibrations below 20 Hz. Hearing can feel vibrations above 20 Hz. Sound vibrates eardrum and other body surfaces but is not felt as touch.
Vision seems unrelated to hearing, but both detect wave frequency and intensity. Hearing detects longitudinal mechanical waves, and vision detects transverse electric waves. Hearing has ten-octave frequency range, and vision has one-octave frequency range. Hearing has higher energy level than vision. Hearing is analytic, but vision is synthetic. Hearing can have interference from more than one source, and vision can have interference from only one source. Hearing uses phase differences, but vision does not. Hearing is silent from most spatial locations, but vision displays information from all scene locations. Hearing has sound attack and decay, but vision is so fast that it has no temporal properties.
Smell and taste seem unrelated to hearing.
Consciousness>Consciousness>Sense>Hearing
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Date Modified: 2022.0224