Amplitude panning
Encyclopedia
Amplitude Panning is a technic in sound engineering where the same sound signal is applied to a number of loudspeaker
s in different directions equidistant from the listener. Then, a virtual source appears to a direction that is dependent on amplitude
s of the loudspeakers. The direction may not coincide with any physical sound source. Most typically amplitude panning has been used with stereophonic loudspeaker setup. However, it is increasingly used to position virtual sources to arbitrary loudspeaker setups.
s to the amplitude difference of in-phase input signals to two loudspeakers.
sound propagation, it has been shown that the sound field presented by these two transducer
s can deliver an appropriate phase difference between the positions of listener’s ears at low frequencies, where the relation between the position of phantom image and the corresponding amplitude ratio may be summarized by the so-called ‘sine law’ (similarly, thetangent law).
The system was designed to work approximately below 1 kHz, above which the given phase difference becomes ambiguous, and so does the position of the sound image. However, it was suggested that the localisation at relatively high frequencies may take advantage of the interaural level difference resulting from the head-shadowing effect.
For the frontal standard configuration, the relation between the inter-channel level difference and the perceived image position has been investigated in many studies, where the target positions were found to be slightly overestimated in many cases. Similar listening tests were also carried out for some asymmetrical lateral configurations, and the results showed that the amplitude-panning method is not as efficient in presenting images to listener’s side as it is to the front.
Loudspeaker
A loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...
s in different directions equidistant from the listener. Then, a virtual source appears to a direction that is dependent on amplitude
Amplitude
Amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system. For example, sound waves in air are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation...
s of the loudspeakers. The direction may not coincide with any physical sound source. Most typically amplitude panning has been used with stereophonic loudspeaker setup. However, it is increasingly used to position virtual sources to arbitrary loudspeaker setups.
History
First invented by Blumlein in early 1930s, original stereophony was a system that converts the phase difference of the signals recorded by a pair of microphoneMicrophone
A microphone is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. In 1877, Emile Berliner invented the first microphone used as a telephone voice transmitter...
s to the amplitude difference of in-phase input signals to two loudspeakers.
Operation
Assuming free fieldFree field
In classical physics, a free field is a field whose equations of motion are given by linear partial differential equations. Such linear PDE's have a unique solution for a given initial condition....
sound propagation, it has been shown that the sound field presented by these two transducer
Transducer
A transducer is a device that converts one type of energy to another. Energy types include electrical, mechanical, electromagnetic , chemical, acoustic or thermal energy. While the term transducer commonly implies the use of a sensor/detector, any device which converts energy can be considered a...
s can deliver an appropriate phase difference between the positions of listener’s ears at low frequencies, where the relation between the position of phantom image and the corresponding amplitude ratio may be summarized by the so-called ‘sine law’ (similarly, thetangent law).
The system was designed to work approximately below 1 kHz, above which the given phase difference becomes ambiguous, and so does the position of the sound image. However, it was suggested that the localisation at relatively high frequencies may take advantage of the interaural level difference resulting from the head-shadowing effect.
For the frontal standard configuration, the relation between the inter-channel level difference and the perceived image position has been investigated in many studies, where the target positions were found to be slightly overestimated in many cases. Similar listening tests were also carried out for some asymmetrical lateral configurations, and the results showed that the amplitude-panning method is not as efficient in presenting images to listener’s side as it is to the front.