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A tuning fork is an acoustic resonator in the form of a two-pronged fork with the prongs (tines) formed from a U-shaped bar of elastic metal. It resonates at a specific constant pitch when set vibrating by striking it against a surface or with an object, and emits a pure musical tone once the high overtones fade out. A tuning fork's pitch depends on the length and mass of the two prongs. They are traditional sources of standard pitch for tuning musical instruments.
The middle ear is the portion of the ear medial to the eardrum, and distal to the oval window of the cochlea.
The ossicles are three bones in either middle ear that are among the smallest bones in the human body. They serve to transmit sounds from the air to the fluid-filled labyrinth (cochlea). The absence of the auditory ossicles would constitute a moderate-to-severe hearing loss. The term "ossicle" literally means "tiny bone". Though the term may refer to any small bone throughout the body, it typically refers to the malleus, incus, and stapes of the middle ear.
The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, the modiolus. A core component of the cochlea is the organ of Corti, the sensory organ of hearing, which is distributed along the partition separating the fluid chambers in the coiled tapered tube of the cochlea.
Longitudinal waves are waves in which the vibration of the medium is parallel to the direction the wave travels and displacement of the medium is in the same direction of the wave propagation. Mechanical longitudinal waves are also called compressional or compression waves, because they produce compression and rarefaction when traveling through a medium, and pressure waves, because they produce increases and decreases in pressure. A wave along the length of a stretched Slinky toy, where the distance between coils increases and decreases, is a good visualization. Real-world examples include sound waves and seismic P-waves.
Infrasound, sometimes referred to as low frequency sound, describes sound waves with a frequency below the lower limit of human audibility. Hearing becomes gradually less sensitive as frequency decreases, so for humans to perceive infrasound, the sound pressure must be sufficiently high. The ear is the primary organ for sensing low sound, but at higher intensities it is possible to feel infrasound vibrations in various parts of the body.
A normal mode of a dynamical system is a pattern of motion in which all parts of the system move sinusoidally with the same frequency and with a fixed phase relation. The free motion described by the normal modes takes place at fixed frequencies. These fixed frequencies of the normal modes of a system are known as its natural frequencies or resonant frequencies. A physical object, such as a building, bridge, or molecule, has a set of normal modes and their natural frequencies that depend on its structure, materials and boundary conditions.
An ear is the organ that enables hearing and body balance using the vestibular system. In mammals the ear is usually described as having three parts: the outer ear, the middle ear and the inner ear. The outer ear consists of the pinna and the ear canal. Since the outer ear is the only visible portion of the ear in most animals, the word "ear" often refers to the external part alone. The middle ear includes the tympanic cavity and the three ossicles. The inner ear sits in the bony labyrinth, and contains structures which are key to several senses: the semicircular canals, which enable balance and eye tracking when moving; the utricle and saccule, which enable balance when stationary; and the cochlea, which enables hearing. The ear is a self cleaning organ through its relationship with earwax and the ear canals. The ears of vertebrates are placed somewhat symmetrically on either side of the head, an arrangement that aids sound localization.
Sound localization is a listener's ability to identify the location or origin of a detected sound in direction and distance.
The brown note, also sometimes called the brown frequency or brown noise, is a hypothetical infrasonic frequency capable of causing fecal incontinence by creating acoustic resonance in the human bowel. Considered an urban myth, the name is a metonym for the common color of human faeces. Attempts to demonstrate the existence of a "brown note" using sound waves transmitted through the air have failed.
The plasmasphere, or inner magnetosphere, is a region of the Earth's magnetosphere consisting of low-energy (cool) plasma. It is located above the ionosphere. The outer boundary of the plasmasphere is known as the plasmapause, which is defined by an order of magnitude drop in plasma density. In 1963 American scientist Don Carpenter and Soviet astronomer Konstantin Gringauz proved the plasmasphere and plasmapause's existence from the analysis of very low frequency (VLF) whistler wave data. Traditionally, the plasmasphere has been regarded as a well behaved cold plasma with particle motion dominated entirely by the geomagnetic field and, hence, co-rotating with the Earth.
Geotail was a satellite that observed the Earth's magnetosphere. It was developed by Japan's ISAS in association with the United States' NASA, and was launched by a Delta II rocket on 24 July 1992 from Cape Canaveral Air Force Station.
Speech science refers to the study of production, transmission and perception of speech. Speech science involves anatomy, in particular the anatomy of the oro-facial region and neuroanatomy, physiology, and acoustics.
The Magnetospheric Multiscale (MMS) Mission is a NASA robotic space mission to study the Earth's magnetosphere, using four identical spacecraft flying in a tetrahedral formation. The spacecraft were launched on 13 March 2015 at 02:44 UTC. The mission is designed to gather information about the microphysics of magnetic reconnection, energetic particle acceleration, and turbulence — processes that occur in many astrophysical plasmas. As of March 2020, the MMS spacecraft have enough fuel to remain operational until 2040.
In physics, sound is a vibration that propagates as an acoustic wave through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the reception of such waves and their perception by the brain. Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of 17 meters (56 ft) to 1.7 centimeters (0.67 in). Sound waves above 20 kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound. Different animal species have varying hearing ranges.
Hearing, or auditory perception, is the ability to perceive sounds through an organ, such as an ear, by detecting vibrations as periodic changes in the pressure of a surrounding medium. The academic field concerned with hearing is auditory science.
Audification is an auditory display technique for representing a sequence of data values as sound. By definition, it is described as a "direct translation of a data waveform to the audible domain." Audification interprets a data sequence and usually a time series, as an audio waveform where input data are mapped to sound pressure levels. Various signal processing techniques are used to assess data features. The technique allows the listener to hear periodic components as frequencies. Audification typically requires large data sets with periodic components.
The ISEE-2 was an Explorer-class daughter spacecraft, International Sun-Earth Explorer-2, was part of the mother/daughter/heliocentric mission. ISEE-2 was a 165.78 kg (365.5 lb) space probe used to study magnetic fields near the Earth. ISEE-2 was a spin-stabilized spacecraft and based on the design of the prior IMP series of spacecraft. ISEE-1 and ISEE-2 were launched on 22 October 1977, and they re-entered on 26 September 1987.
Donald Alfred Gurnett was an American physicist and professor at the University of Iowa who specialized in plasma physics.
Craig Allen Kletzing was an American plasma physicist and professor at the University of Iowa, known for his work in space plasmas and laboratory plasmas. He conducted pioneering work in kinetic Alfvén waves, developed instruments for various NASA missions, and taught college level physics.
References
- ↑ "Ganymede Sings, Europa Dazzles, Callisto Confounds". NASA Jet Propulsion Laboratory - The Galileo Messenger. 1997-04-10. Archived from the original on 1997-04-10. Retrieved 2023-09-22.
- ↑ Gurnett, Donald A. (1998). "14. Principles of Space Plasma Wave Instrument Design". In Pfaff, F.; Borovsky, E.; Young, T. (eds.). Measurement Techniques in Space Plasmas: Fields. Geophysical Monograph Series. Vol. 103. Washington, D. C.: American Geophysical Union. doi:10.1029/gm103. ISBN 978-0-87590-086-5.
{{cite book}}: CS1 maint: date and year (link) - ↑ Matsumoto, H.; Nagano, I.; Anderson, R. R.; Kojima, H.; Hashimoto, K.; Tsutsui, M.; Okada, T.; Kimura, I.; Omura, Y.; Okada, M. (1994). "Plasma Wave Observations with GEOTAIL Spacecraft". Journal of Geomagnetism and Geoelectricity. 46 (1): 59–95. Bibcode:1994JGG....46...59M. doi: 10.5636/jgg.46.59 .
- ↑ Gurnett, D. A.; Persoon, A. M.; Randall, R. F.; Odem, D. L.; Remington, S. L.; Averkamp, T. F.; Debower, M. M.; Hospodarsky, G. B.; Huff, R. L.; Kirchner, D. L.; Mitchell, M. A.; Pham, B. T.; Phillips, J. R.; Schintler, W. J.; Sheyko, P. (1995). "The Polar plasma wave instrument". Space Science Reviews. 71 (1): 597–622. Bibcode:1995SSRv...71..597G. doi:10.1007/BF00751343. hdl: 2060/19960016982 . ISSN 1572-9672. S2CID 123290345.
- ↑ Gurnett, D. A.; Kurth, W. S.; Kirchner, D. L.; Hospodarsky, G. B.; Averkamp, T. F.; Zarka, P.; Lecacheux, A.; Manning, R.; Roux, A.; Canu, P.; Cornilleau-Wehrlin, N.; Galopeau, P.; Meyer, A.; Boström, R.; Gustafsson, G. (2004). "The Cassini Radio and Plasma Wave Investigation". Space Science Reviews. 114 (1): 395–463. Bibcode:2004SSRv..114..395G. doi:10.1007/s11214-004-1434-0. ISSN 1572-9672. S2CID 53455932.
- ↑ Webster, Guy; Savage, Donald (2022-10-24). "NASA Music out of This World". NASA Jet Propulsion Laboratory (JPL). Retrieved 2023-09-22.
- ↑ Mössinger, Juliane C. (2003-04-10). "Sounds from space". Nature. 422 (6932): 565. doi: 10.1038/422565a . ISSN 1476-4687. S2CID 4412023.