A microphone array is any number of microphones operating in tandem. There are many applications:
A hydrophone is a microphone designed to be used underwater for recording or listening to underwater sound. Most hydrophones are based on a piezoelectric transducer that generates an electric potential when subjected to a pressure change, such as a sound wave. Some piezoelectric transducers can also serve as a sound projector, but not all have this capability, and some may be destroyed if used in such a manner.
A microphone, colloquially named mic or mike, is a device – a transducer – that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public events, motion picture production, live and recorded audio engineering, sound recording, two-way radios, megaphones, radio and television broadcasting, and in computers for recording voice, speech recognition, VoIP, and for non-acoustic purposes such as ultrasonic sensors or knock sensors.
Binaural recording is a method of recording sound that uses two microphones, arranged with the intent to create a 3-D stereo sound sensation for the listener of actually being in the room with the performers or instruments. This effect is often created using a technique known as "dummy head recording", wherein a mannequin head is outfitted with a microphone in each ear. Binaural recording is intended for replay using headphones and will not translate properly over stereo speakers. This idea of a three dimensional or "internal" form of sound has also translated into useful advancement of technology in many things such as stethoscopes creating "in-head" acoustics and IMAX movies being able to create a three dimensional acoustic experience.
A head-related transfer function (HRTF), also sometimes known as the anatomical transfer function (ATF), is a response that characterizes how an ear receives a sound from a point in space. As sound strikes the listener, the size and shape of the head, ears, ear canal, density of the head, size and shape of nasal and oral cavities, all transform the sound and affect how it is perceived, boosting some frequencies and attenuating others. Generally speaking, the HRTF boosts frequencies from 2–5 kHz with a primary resonance of +17 dB at 2,700 Hz. But the response curve is more complex than a single bump, affects a broad frequency spectrum, and varies significantly from person to person.
Surround sound is a technique for enriching the fidelity and depth of sound reproduction by using multiple audio channels from speakers that surround the listener. Its first application was in movie theaters. Prior to surround sound, theater sound systems commonly had three "screen channels" of sound, from loudspeakers located in front of the audience at the left, center, and right. Surround sound adds one or more channels from loudspeakers behind the listener, able to create the sensation of sound coming from any horizontal direction 360° around the listener. Surround sound formats vary in reproduction and recording methods along with the number and positioning of additional channels. The most common surround sound specification, the ITU's 5.1 standard, calls for 6 speakers: Center (C) in front of the listener, Left (L) and Right (R) at angles of 60° on either side of the center, and Left Surround (LS) and Right Surround (RS) at angles of 100–120°, plus a subwoofer whose position is not critical.
Active noise control (ANC), also known as noise cancellation, or active noise reduction (ANR), is a method for reducing unwanted sound by the addition of a second sound specifically designed to cancel the first.
Sound localization is a listener's ability to identify the location or origin of a detected sound in direction and distance.
Stereophonic sound or, more commonly, stereo, is a method of sound reproduction that creates an illusion of multi-directional audible perspective. This is usually achieved by using two or more independent audio channels through a configuration of two or more loudspeakers in such a way as to create the impression of sound heard from various directions, as in natural hearing. Thus the term "stereophonic" applies to so-called "quadraphonic" and "surround-sound" systems as well as the more common two-channel, two-speaker systems. It is often contrasted with monophonic, or "mono" sound, where audio is heard as coming from one position, often ahead in the sound field. Stereo sound has been in common use since the 1970s in entertainment systems such as broadcast radio, TV, recorded music, internet, computer audio, and cinema.
In acoustics, the dummy head recording is a method of recording used to generate binaural recordings. The tracks are then listened to through headphones allowing for the listener to hear from the dummy’s perspective. The dummy head is designed to record multiple sounds at the same time enabling it to be exceptional at recording music as well as in other industries where multiple sound sources are involved.
The ORTF stereo microphone system, also known as Side-Other-Side, is a microphone technique used to record stereo sound.
The NOS stereo technique is a method of capturing stereo sound.
Virtual acoustic space (VAS), also known as virtual auditory space, is a technique in which sounds presented over headphones appear to originate from any desired direction in space. The illusion of a virtual sound source outside the listener's head is created.
A boundary microphone is a small omnidirectional condenser mic capsule positioned near or flush with a boundary (surface). The arrangement provides a directional half-space pickup pattern while delivering a relatively phase-coherent output signal.
Acoustic location is the use of sound to determine the distance and direction of its source or reflector. Location can be done actively or passively, and can take place in gases, liquids, and in solids.
Blumlein pair is the name for a stereo recording technique invented by Alan Blumlein for the creation of recordings that, upon replaying through headphones or loudspeakers, recreate the spatial characteristics of the recorded signal.
Cook Records was a record label founded by Emory Cook (1913–2002), an audio engineer and inventor. From 1952 to 1966, Cook used his Sounds of our Times and Cook Laboratories record labels to demonstrate his philosophy about sound, recording equipment, and manufacturing techniques.
There exist a number of well-developed microphone techniques used for recording musical, film, or voice sources. Choice of technique depends on a number of factors, including:
Ambiophonics is a method in the public domain that employs digital signal processing (DSP) and two loudspeakers directly in front of the listener in order to improve reproduction of stereophonic and 5.1 surround sound for music, movies, and games in home theaters, gaming PCs, workstations, or studio monitoring applications. First implemented using mechanical means in 1986, today a number of hardware and VST plug-in makers offer Ambiophonic DSP. Ambiophonics eliminates crosstalk inherent in the conventional “stereo triangle” speaker placement, and thereby generates a speaker-binaural soundfield that emulates headphone-binaural sound, and creates for the listener improved perception of “reality” of recorded auditory scenes. A second speaker pair can be added in back in order to enable 360° surround sound reproduction. Additional surround speakers may be used for hall ambience, including height, if desired.
3D sound localization refers to an acoustic technology that is used to locate the source of a sound in a three-dimensional space. The source location is usually determined by the direction of the incoming sound waves and the distance between the source and sensors. It involves the structure arrangement design of the sensors and signal processing techniques.
