terrestrial Whistlers, 1976
these FM-selfbroadcasting aluminum Whistlers were suspended between trees at a height 20 feet above ground and included inch & 3/4 inch diameters (QT.mov)
Whistler detail (2 sensors showing: top & lower right)
the sensors (Barcus-Berry guitar pickups) are beeswaxed onto the aluminum and 22 gauge pigtail surfaces
running parallel 200 feet between birches and 25 feet above ground beeswax-held sensors can be attached to any node w/beeswax; this Windribbon (below) had a triaxial sensor (Columbia accelerometer) and three sounds could be monitored (in the x,y,z axes) or via FM transmitter
in this 1873 bridge example sensors could be placed anywhere for multiple vibrational monitoring; however, 1/4 magnetic tape was applied to cleaned and degreased surfaces, covered with a clear adheasive tape and was left in place for 3 weeks. The playback contained pink, brown and white noises.
the most sensitive sensors (Radio Shack, surplus electronic stores) are the crystal pickups and each having a volume control; the fan provided the breeze and, these were used on surfaces where suspected sounds would be heard when a surface was slightly moved by the wind.
input from nature
A input session used: solar panel, traxial and accelerometer sensor(s), mixer, preamp and/or a line out or selfbroadcasting FM transmissions.
output to studio mixer
Output from FM receivers, carrying these selfbroadcasting sessions used balanced cables into a mixer/recorder to an inside studio described below.
Descibed as contextual soundscapes, the results achieve 4 channels into 8 amplifiers and are heard distributed among 200 speakers. This results in a transferred spatial context being listened to from behind and beneath all planes of my project room (a false floor allowed for soundings from below).
Macs, Sound Designer, Deck II, ProTools and an AMIII sound card allow for the mixdown of output (2a-2d) to the amped speakers.(picts:soundroom)
My current 03-04, 05- projects anticipate useing the sensor.
example definitions of soundscape soundscape soundwalk
leif BRUSH use back at top left in this browser
What is a Microflown?
For more than a century the acoustical world has only been working with pressure microphones that can be regarded as "acoustic voltage meters". The equivalent of "an acoustical ampere" meter was not available.
Acoustical engineers found practical ways to overcome this missing dimension, using not reliable and laboursome methods. This is no longer necessary.
The Microflown is an acoustic sensor measuring particle velocity instead of sound pressure, which is usually measured by conventional microphones.
It is a thermal sensor that operates with two very thin and closely spaced heated wires. Particle velocity will cause a thermal imbalance that can be sensed.
The Microflown is a very small sensor that is made by micromaching: it is a silicon based sort of microphone. The Microflown itself is so small that it is difficult to see without a microscope.
In a measurement point of view, a Microflown is an acoustic current meter whereas the regular microphones are more like voltage meters.
In a audio point of view, the Microflown is a directional microphone (figure of eight) that operates down to the lowest frequencies (in fact down to 0Hz). The signal to noise ratio is very high at these lower frequencies. back to your previous place
USP : Ultimative sound sample
Microflown of high-speed microphones
Conventional microphones measure the pressure
change caused by an acoustic wave. Microflown of high-speed microphones
measure however directly the particle movement in air. In addition
two tiny small platinum wires on approx. 200°C are heated
up. The acoustic wave in air lets the air molecules by-flow differently
fast at this Draehtchen, which cools these down again differently.
This differential cooling changes the resistance of the Draehtchen,
which by appropriate transformation as electrical signal becomes
Microflown Ultimate sound sample (USP): Loudness probe in a completely new technology - the direct measurement of the particle speed is in air the crucial novelty. Measurement at an individual point, of:
3D particle speed
3D sound energy
3D acoustic impedance
The sensor is in a housing from stainless steel, amounts to 12.7 mm in the diameter and 9 cm in the length.
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