Acoustics

The outer ear is the external portion of the ear, which consists of the auricle (also pinna) and the ear canal.

Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average, or equilibrium) atmospheric pressure, caused by a sound wave.

Musica universalis (literally universal music), also called Music of the spheres or Harmony of the Spheres, is an ancient philosophical concept that regards proportions in the movements of celestial bodies—the Sun, Moon, and planets—as a form of musica (the Medieval Latin term for music).

Reverberation, in psychoacoustics and acoustics, is the persistence of sound after a sound is produced.

The phonautograph is the earliest known device for recording sound.

A resonance chamber uses resonance to amplify sound.

Acoustic waves are a type of longitudinal waves that propagate by means of adiabatic compression and decompression.

Frequency is the number of occurrences of a repeating event per unit time.

The speed of sound is the distance travelled per unit time by a sound wave as it propagates through an elastic medium.

Absolute pitch (AP), widely referred to as perfect pitch, is a rare auditory phenomenon characterized by the ability of a person to identify or re-create a given musical note without the benefit of a reference tone.

In acoustics, a beat is an interference pattern between two sounds of slightly different frequencies, perceived as a periodic variation in volume whose rate is the difference of the two frequencies.

The soundscape is the component of the acoustic environment that can be perceived by humans.

Hearing, auditory perception, or audition is the ability to perceive sound by detecting vibrations, changes in the pressure of the surrounding medium through time, through an organ such as the ear.

Medical ultrasound (also known as diagnostic sonography or ultrasonography) is a diagnostic imaging technique based on the application of ultrasound.

The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the inner ear.

Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals.

Stereophonic sound or, more commonly, stereo, is a method of sound reproduction that creates an illusion of multi-directional audible perspective.

Sound energy density or sound density is the sound energy per unit volume.

The auricle or auricula is the visible part of the ear that resides outside of the head.

Bioacoustics is a cross-disciplinary science that combines biology and acoustics.

Granular synthesis is a basic sound synthesis method that operates on the microsound time scale.

In chemistry, the study of sonochemistry is concerned with understanding the effect of ultrasound in forming acoustic cavitation in liquids, resulting in the initiation or enhancement of the chemical activity in the solution.

The field of underwater acoustics is closely related to a number of other fields of acoustic study, including sonar, transduction, acoustic signal processing, acoustical oceanography, bioacoustics, and physical acoustics.

The purpose of the International Commission for Acoustics (ICA) is to promote international development and collaboration in all fields of acoustics including research, development, education, and standardisation.

Nonlinear acoustics (NLA) is a branch of physics and acoustics dealing with sound waves of sufficiently large amplitudes.

Acoustic location is the science of using sound to determine the distance and direction of its source or reflector.

The term harmonic in its strictest sense describes any member of the harmonic series.

In acoustics, the dummy head recording (also known as artificial head, Kunstkopf or Head and Torso Simulator) is a method of recording used to generate binaural recordings.

The precedence effect or law of the first wavefront is a binaural psychoacoustic effect.

An audio frequency (abbreviation: AF) or audible frequency is characterized as a periodic vibration whose frequency is audible to the average human.

Auditory masking occurs when the perception of one sound is affected by the presence of another sound.

Room acoustics describes how sound behaves in an enclosed space.

Acoustic quieting is the process of making machinery quieter by damping vibrations to prevent them from reaching the observer.

Atmospheric diffraction is manifested in the following principal ways: * Optical atmospheric diffraction * Radio wave diffraction is the scattering of radio frequency or lower frequencies from the Earth's ionosphere, resulting in the ability to achieve greater distance radio broadcasting.

A whistling kettle is a kettle fitted with a device that emits an audible whistle when the water in the kettle starts to boil.

Pre-echo, sometimes called a forward echo, (not to be confused with reverse echo) is a digital audio compression artifact where a sound is heard before it occurs (hence the name).

Diffuse field acoustic testing is the testing of the mechanical resistance of a spacecraft to the acoustic pressures during launch.