A whispering gallery is usually a circular, hemispherical, elliptical or ellipsoidal enclosure, often beneath a dome or a vault, in which whispers can be heard clearly in other parts of the gallery. Such galleries can also be set up using two parabolic dishes. Sometimes the phenomenon is detected in caves.
A whispering gallery is most simply constructed in the form of a circular wall, and allows whispered communication from any part of the internal side of the circumference to any other part. The sound is carried by waves, known as whispering-gallery waves, that travel around the circumference clinging to the walls, an effect that was discovered in the whispering gallery of St Paul's Cathedral in London. [1] The extent to which the sound travels at St Paul's can also be judged by clapping in the gallery, which produces four echoes. [2] Other historical examples [3] [4] [5] are the Gol Gumbaz mausoleum in Bijapur, India and the Echo Wall of the Temple of Heaven in Beijing. A hemispherical enclosure will also guide whispering gallery waves. The waves carry the words so that others will be able to hear them from the opposite side of the gallery.
The gallery may also be in the form of an ellipse or ellipsoid, [4] with an accessible point at each focus. In this case, when a visitor stands at one focus and whispers, the line of sound emanating from this focus reflects directly to the focus at the other end of the gallery, where the whispers may be heard. In a similar way, two large concave parabolic dishes, serving as acoustic mirrors, may be erected facing each other in a room or outdoors to serve as a whispering gallery, a common feature of science museums. Egg-shaped galleries, such as the Golghar Granary at Bankipore, [3] and irregularly shaped smooth-walled galleries in the form of caves, such as the Ear of Dionysius in Syracuse, [4] also exist.
The term whispering gallery has been borrowed in the physical sciences to describe other forms of whispering-gallery waves such as light or matter waves. [16]
Acoustics is a branch of physics that deals with the study of mechanical waves in gases, liquids, and solids including topics such as vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics technology may be called an acoustical engineer. The application of acoustics is present in almost all aspects of modern society with the most obvious being the audio and noise control industries.
John William Strutt, 3rd Baron Rayleigh, was an English mathematician and physicist who made extensive contributions to science. He spent all of his academic career at the University of Cambridge. Among many honours, he received the 1904 Nobel Prize in Physics "for his investigations of the densities of the most important gases and for his discovery of argon in connection with these studies." He served as president of the Royal Society from 1905 to 1908 and as chancellor of the University of Cambridge from 1908 to 1919.
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.
A waveguide is a structure that guides waves by restricting the transmission of energy to one direction. Common types of waveguides include acoustic waveguides which direct sound, optical waveguides which direct light, and radio-frequency waveguides which direct electromagnetic waves other than light like radio waves.
A megaphone, speaking trumpet, bullhorn, blowhorn, or loudhailer is usually a portable or hand-held, cone-shaped acoustic horn used to amplify a person's voice or other sounds and direct it in a given direction. The sound is introduced into the narrow end of the megaphone, by holding it up to the face and speaking into it, and the sound waves radiate out the wide end. A megaphone increases the volume of sound by increasing the acoustic impedance seen by the vocal cords, matching the impedance of the vocal cords to the air, so that more sound power is radiated. It also serves to direct the sound waves in the direction the horn is pointing. It somewhat distorts the sound of the voice because the frequency response of the megaphone is greater at higher sound frequencies.
Room acoustics is a subfield of acoustics dealing with the behaviour of sound in enclosed or partially-enclosed spaces. The architectural details of a room influences the behaviour of sound waves within it, with the effects varying by frequency. Acoustic reflection, diffraction, and diffusion can combine to create audible phenomena such as room modes and standing waves at specific frequencies and locations, echos, and unique reverberation patterns.
The Rijke tube is a cylindrical tube with both ends open, inside of which a heat source is placed that turns heat into sound, by creating a self-amplifying standing wave, due to thermo-acoustic instability. It is an entertaining phenomenon in acoustics and is an excellent example of resonance.
Gol Gumbaz, also written Gol Gumbad, is a 17th-century mausoleum located in Bijapur, a city in Karnataka, India. It houses the remains of Mohammad Adil Shah, seventh sultan of the Adil Shahi dynasty, and some of his relatives. Begun in the mid-17th century, the structure never reached completion. The mausoleum is notable for its scale and exceptionally large dome. The structure is an important example of Adil Shahi architecture.
An acoustic mirror is a passive device used to reflect and focus (concentrate) sound waves. Parabolic acoustic mirrors are widely used in parabolic microphones to pick up sound from great distances, employed in surveillance and reporting of outdoor sporting events. Pairs of large parabolic acoustic mirrors which function as "whisper galleries" are displayed in science museums to demonstrate sound focusing.
3D audio effects are a group of sound effects that manipulate the sound produced by stereo speakers, surround-sound speakers, speaker-arrays, or headphones. This frequently involves the virtual placement of sound sources anywhere in three-dimensional space, including behind, above or below the listener.
Sound localization is a listener's ability to identify the location or origin of a detected sound in direction and distance.
Kresge Auditorium is an auditorium structure at the Massachusetts Institute of Technology, located at 48 Massachusetts Avenue, Cambridge, Massachusetts. It was designed by the Finnish-American architect Eero Saarinen, with ground-breaking in 1953 and dedication in 1955. The building was named for its principal funder, Sebastian S. Kresge, founder of S. S. Kresge Stores and the Kresge Foundation.
The Mapparium is a three-story-tall globe made of stained glass that is viewed from a 30-foot-long (9.1 m) bridge through its interior. As of August 2021, it is part of the "How Do You See the World?" exhibit of the Christian Science Publishing Society in Boston, Massachusetts.
A parametric array, in the field of acoustics, is a nonlinear transduction mechanism that generates narrow, nearly side lobe-free beams of low frequency sound, through the mixing and interaction of high frequency sound waves, effectively overcoming the diffraction limit associated with linear acoustics. The main side lobe-free beam of low frequency sound is created as a result of nonlinear mixing of two high frequency sound beams at their difference frequency. Parametric arrays can be formed in water, air, and earth materials/rock.
Underwater acoustics is the study of the propagation of sound in water and the interaction of the mechanical waves that constitute sound with the water, its contents and its boundaries. The water may be in the ocean, a lake, a river or a tank. Typical frequencies associated with underwater acoustics are between 10 Hz and 1 MHz. The propagation of sound in the ocean at frequencies lower than 10 Hz is usually not possible without penetrating deep into the seabed, whereas frequencies above 1 MHz are rarely used because they are absorbed very quickly.
The antiquity of architecture of Karnataka can be traced to its southern Neolithic and early Iron Age, Having witnessed the architectural ideological and utilitarian transformation from shelter- ritual- religion. Here the nomenclature 'Architecture' is as old as c.2000 B.C.E. The upper or late Neolithic people in order to make their shelters by their own they constructed huts made of wattle and doab, that were buttressed by stone boulders, presumably having conical roof resting on the bamboo or wooden posts into red murram or paved granite chips as revealed in archaeological excavations in sites like Brhamagiri, Sanganakallu, Tekkalakota, Piklihal. Megaliths are the dominant archaeological evidence of the early Iron Age. There are more than 2000 early Iron Age burial sites on record, who laid the foundation for a high non-perishable architecture in the form of various distinct architectural styles of stone-built burials, which are ritualistic in its character. The active religious architecture is evident 345 with that of the Kadamba Dynasty. Karnataka is a state in the southern part of India originally known as the State of Mysore. Over the centuries, architectural monuments within the region displayed a diversity of influences, often relaying much about the artistic trends of the rulers of twelve different dynasties. Its architecture ranges dramatically from majestic monolith, such as the Gomateshwara, to Hindu and Jain places of worship, ruins of ancient cities, mausoleums and palaces of different architectural hue. Mysore Kingdom (Wodeyar) rule has also given an architectural master structure in the St. Philomena's Church at Mysore which was completed in 1956, in addition to many Dravidian style architectural temples. Two of the monuments are listed under the UNESCO World Heritage List of 22 cultural monuments in India. Styles of Indo-Saracenic, Renaissance, Corinthian, Hindu, Indo-Greek and Indo-British style palaces were built in Mysore, the city of palaces. Sikh architecture at Bidar (1512) and also in Bangalore in 1956 can also be cited as having an impact on the architectural composition of the state.
Whispering-gallery waves, or whispering-gallery modes, are a type of wave that can travel around a concave surface. Originally discovered for sound waves in the whispering gallery of St Paul's Cathedral, they can exist for light and for other waves, with important applications in nondestructive testing, lasing, cooling and sensing, as well as in astronomy.
Michael Bruce Odland, known as Bruce Odland, is a composer, sound artist and sonic thinker. He is known for large-scale sound installations in public spaces, creating unique instruments that reveal music inherent in natural and urban environments, and for his pioneering work in theater, film and interactive multi-media. He lives and works in Westchester County, New York. Odland's musical sculptures and sound installations have been shown in major cities such as New York, Berlin, and Zurich; in art museums including the Denver Art Museum, the Field Museum and Mass MoCA; and at the international documenta14, Ars Electronica, Edinburgh International and Salzburg Festivals. Many of his installations are collaborations with Austrian sound artist Sam Auinger, with whom he formed an artistic partnership O+A in 1989. Together they have created more than 50 sound installations in Europe, North America and Asia.
An elliptical dome, or an oval dome, is a dome whose bottom cross-section takes the form of an ellipse. Technically, an ellipsoidal dome has a circular cross-section, so is not quite the same.
