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In acoustics, dummy head recording (also known as artificial head or Kunstkopf) is a method used to make stereo recordings that allow a listener wearing headphones to perceive the directionality and the room acoustics of single or multiple sources. Wikipedia does not have an article with this exact name. ... Dummy head being used for binaural recording; the second microphone is obscured. ... Acoustics is a branch of physics and is the study of sound, mechanical waves in gases, liquids, and solids. ... In popular usage, stereo generally to dual-channel sound recording and sound reproduction – sound that contains data for more than one speaker simultaneously. ... Headphones (also known as earphones, earbuds, stereophones, headsets, or by the slang term cans) are a pair of transducers that receive an electrical signal from a media player or receiver and use speakers placed in close proximity to the ears (hence the name earphone) to convert the signal into audible... Acoustics is a branch of physics and is the study of sound, mechanical waves in gases, liquids, and solids. ...

Human perception of the direction of a sound source is complex, and consists of:

1. Simple "left-right" information can be gained from relative level differences and time of arrival differences of the sound in each ear.
2. For percussive sounds, the impact of a shockwave can register perceptibly on the skin (typically the upper torso), with the earliest and strongest sensory stimulus coming from the region(s) of skin aligned perpendicular to the direction of the sound-source.
3. The human head imprints frequency-dependent distortions of phase and amplitude on sound reaching the eardrums, that are frequency-dependent level differences and these distortion effects vary with the direction of the sound source (being caused by the geometry and sound-transmitting characteristics of the sinus and throat cavities, eustachian tubes, inner ear, external ears, and other hard and soft tissues in the head and upper body (see: head-related transfer function, "HRTF").

Conventional stereo recording only makes use of effect [1]. Dummy head recording uses both [1] and [3]. Phase is an overloaded word used for: instantaneous phase: the current position in the cycle of something that changes cyclically phase shift: a constant difference/offset between two instantaneous phases, particularly when one is a standard reference Waves are amplitudes that change cyclically, often modeled as sinusoidal functions of time... Amplitude is a nonnegative scalar measure of a waves magnitude of oscillation, that is, magnitude of the maximum disturbance in the medium during one wave cycle. ... A sinus is a pouch or cavity in any organ or tissue, or an abnormal cavity or passage caused by the destruction of tissue. ... Anatomy of the human ear. ... HRTFs for left and right ear (expressed here as HRIRs) describe the filtering of a sound source (x(t)) before it is perceived at the left and right ears as xL(t) and xR(t), respectively. ...

Methods

There are three main ways of making a recording that uses this last effect to encode directionality information:

1. dummy head recording uses an artificial model of a human head, built from selected acoustic materials to emulate the sound-transmitting characteristics of a real human head, with two microphone inserts embedded at the "eardrum" locations,
2. simulated dummy head recording processes a signal electronically to imprint the HRTF information associated with a specified direction, and
3. finally, a pair of specially-designed microphones can be worn by a volunteer, fitted inside their ears, to make use of "real" head acoustics.

History

Historically, dummy head recordings have been associated with the use of a real synthetic head, the "Kunstkopf". The "head" could be placed in a concert hall to make a live orchestral recording, or actors could stand around the head when recording their dialogue. The head could also be used to imprint positional information on prerecorded sound effects by playing sounds through a loudspeaker placed in a suitable position by the head, and rerecording the result (for instance, it might be desirable for birdsong or thunder to seem to be coming from above the listener; this would not be achieveable using conventional methods).

In the 1990's, electronic devices were made commercially available that used DSP processing power to reproduce an HRTF digitally. These devices allowed the operator to use dials to adjust the apparent direction of sounds in real time. They were unusual and expensive, but allowed an operator to "position" pre-recorded special effects quickly and conveniently, and also to move sound sources dynamically. By manipulating the dials, the sound engineer could take a monophonic recording of a passing car and make it sound to the listener as if it was passing behind him or her, in a particular direction. With a "physical" dummy head, this would have also required a rerecording booth, and either a single moving loudspeaker or an array of speakers and some sort of multiple panning or switching device. The term DSP, when used by itself, can refer to: The sterilisation process Dry Sterilisation Process for the cold and fast sterilisation of surfaces. ...

As portable digital recorders (using DAT and minidisc formats) became more popular, a market also arose for miniature "in-ear" microphones such as the Sound Professionals SP-TFB-2[1] that could be "worn" by the operator inside their own ears to make "dummy head" recordings. Since these devices look like personal stereo "earbuds", they can be worn unobtrusively and are especially useful for making "audience" recordings of concerts and other live events, or for recording "ambient" sounds (such as birdsong, or traffic noises, or crowd sounds) with a realistic three-dimensional soundfield, which can later be mixed in together with more conventional recordings. A convincing radio play scene with two characters talking in a railway station could then be created by recording the actors in the studio, using in-ear microphones to record ambient "railway station" noises, and then mixing the two together. The disadvantage of the "in-ear" method for recording important events is that the wearer cannot wear earphones to monitor the recording, cannot receive audible instructions (without these being recorded), and cannot turn or dip their head without affecting the recording. They also have to be careful not to cough or clear their throat while recording. DAT can mean: day after tomorrow, a J-Pop band. ... // Overview The MiniDisc logo A MiniDisc (MD) is a disc-based data storage device intended for storage of digitized audio. ...

Another problem with "in-ear" recording is that the effectiveness of the effect depends partly on the degree of correspondence between the properties of the recordist's head and the head of the listener - although the recordings may sound compelling to the person who made them, there is currently no easy way to rate a particular person's head characteristics to assess their suitability as a "dummy head" recordist.

It seems likely that a software solution may also appear at some point that would allow a desktop PC to be used to imprint HRTF characteristics onto a digital audio recording. At the time of writing, this option does not yet seem to be available. A stylised illustration of a modern personal computer A personal computer (PC) is usually a microcomputer whose price, size, and capabilities make it suitable for personal usage. ... 2005 is a common year starting on Saturday of the Gregorian calendar. ...

Example

• Please note that the desired effect will only be achieved if stereo headphones are being used