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.
Syracuse is a historic city on the Italian island of Sicily, the capital of the Italian province of Syracuse. The city is notable for its rich Greek and Roman history, culture, amphitheatres, architecture, and as the birthplace and home of the pre-eminent mathematician and engineer Archimedes. This 2,700-year-old city played a key role in ancient times, when it was one of the major powers of the Mediterranean world. Syracuse is located in the southeast corner of the island of Sicily, next to the Gulf of Syracuse beside the Ionian Sea. It is situated in a drastic rise of land with 2,000 metres (6,600 ft) depths being close to the city offshore although the city itself is generally not so hilly in comparison.
A bunker is a defensive military fortification designed to protect people and valued materials from falling bombs, artillery, or other attacks. Bunkers are almost always underground, in contrast to blockhouses which are mostly above ground. They were used extensively in World War I, World War II, and the Cold War for weapons facilities, command and control centers, and storage facilities. Bunkers can also be used as protection from tornadoes.
A shofar is an ancient musical horn typically made of a ram's horn, used for Jewish religious purposes. Like the modern bugle, the shofar lacks pitch-altering devices, with all pitch control done by varying the player's embouchure. The shofar is blown in synagogue services on Rosh Hashanah and at the end of Yom Kippur; it is also blown every weekday morning in the month of Elul running up to Rosh Hashanah. Shofars come in a variety of sizes and shapes, depending on the choice of animal and level of finish.
Dionysius I or Dionysius the Elder was a Greek tyrant of Syracuse, Sicily. He conquered several cities in Sicily and southern Italy, opposed Carthage's influence in Sicily and made Syracuse the most powerful of the Western Greek colonies. He was regarded by the ancients as an example of the worst kind of despot: cruel, suspicious, and vindictive.
In audio signal processing and acoustics, an echo is a reflection of sound that arrives at the listener with a delay after the direct sound. The delay is directly proportional to the distance of the reflecting surface from the source and the listener. Typical examples are the echo produced by the bottom of a well, by a building, or by the walls of an enclosed room and an empty room.
The Rock of Gibraltar is a highly strategic monolithic limestone mountain 426 m (1,398 ft) high dominating the western entrance to the Mediterranean Sea. It is situated near the end of a narrow 9 km long promontory stretching due south into the Mediterranean Sea and is located within the British territory of Gibraltar, and is 27 km north-east of Tarifa, Spain, the southwestern tip of Europe on the Iberian Peninsula. The rock serves as an impregnable fortress and contains a labyrinthine network of man-made tunnels known as the Tunnels of Gibraltar. Most of the Rock's upper area comprises a nature reserve which is home to about 300 Barbary macaques. It is a major tourist attraction.
A grotto is a natural or artificial cave used by humans in both modern times and antiquity, and historically or prehistorically. Naturally occurring grottoes are often small caves near water that are usually flooded or often flooded at high tide. Sometimes, artificial grottoes are used as garden features. The Grotta Azzurra at Capri and the grotto at Tiberius' Villa Jovis in the Bay of Naples are examples of popular natural seashore grottoes.
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.
Cave popcorn, or coralloids, are small nodes of calcite, aragonite or gypsum that form on surfaces in caves, especially limestone caves. They are a common type of speleothem.
Helmholtz resonance, also known as wind throb, refers to the phenomenon of air resonance in a cavity, an effect named after the German physicist Hermann von Helmholtz. This type of resonance occurs when air is forced in and out of a cavity, causing the air inside to vibrate at a specific natural frequency. The principle is widely observable in everyday life, notably when blowing across the top of a bottle, resulting in a resonant tone.
Hearing range describes the frequency range that can be heard by humans or other animals, though it can also refer to the range of levels. The human range is commonly given as 20 to 20,000 Hz, although there is considerable variation between individuals, especially at high frequencies, and a gradual loss of sensitivity to higher frequencies with age is considered normal. Sensitivity also varies with frequency, as shown by equal-loudness contours. Routine investigation for hearing loss usually involves an audiogram which shows threshold levels relative to a normal.
The Round House was the first permanent building built in the Swan River Colony. Built in late 1830 and opened in 1831, it is the oldest building still standing in Western Australia.
An ear trumpet is a tubular or funnel-shaped device which collects sound waves and leads them into the ear. They are used as hearing aids, resulting in a strengthening of the sound energy impact to the eardrum and thus improved hearing for a deaf or hard-of-hearing individual. Ear trumpets were made of sheet metal, silver, wood, snail shells or animal horns. They have largely been replaced in wealthier areas of the world by modern hearing aid technology that is much smaller and less obtrusive, albeit more expensive.
The Wieliczka Salt Mine is a salt mine in the town of Wieliczka, near Kraków in southern Poland.
The Necropolis of Pantalica is a collection of cemeteries with rock-cut chamber tombs in southeast Sicily, Italy. Dating from the 13th to the 7th centuries BC, there was thought to be over 5,000 tombs, although the most recent estimate suggests a figure of just under 4,000. They extend around the flanks of a large promontory located at the junction of the Anapo river with its tributary, the Calcinara, about 23 km (14 mi) northwest of Syracuse. Together with the city of Syracuse, Pantalica was listed as a UNESCO World Heritage Site in 2005.
Poca Roca Cave is a cave in the British Overseas Territory of Gibraltar.
The Greek theatre of Syracuse lies on the south slopes of the Temenite hill, overlooking the modern city of Syracuse in southeastern Sicily, Italy. It was first built in the 5th century BC, rebuilt in the 3rd century BC and renovated again in the Roman period. Today, it is a part of the Unesco World Heritage Site of "Syracuse and the Rocky Necropolis of Pantalica".
The Caves of Maastricht, also known as the caves of Mount Saint Peter or the Maastricht Underground, are a collection of limestone quarries in Maastricht, the Netherlands, the origins of which date back to the 13th century.
The Bar Kokhba hiding complexes, including cliff shelters, are underground places of refuge created by Jewish rebels and their communities of the Shephelah and the Lower Galilee while preparing for the Bar Kokhba revolt, with at least the Judaean ones actually being used during the fighting. Natural caves were also used as refuge caves. The man-made hiding complexes and refuge caves in the Judean desert cliffs were rock-carved spaces, connected to one another by low and narrow passages. According to research, these systems were hewn by the supporters and fighters of Bar Kokhba as preparation for the revolt pursued by the Jews against the Roman Empire in 132-135 CE.
Syracuse (SR, Sicily, Italy)
