Latest microphone technology - Pressure variations, whether in air, water or other mediums, which the human ear can detect, are considered sounds. Acoustics is the science or the study of sound. Sound can be generally pleasing to the ear, as in music, or undesirable, referred to as noise. The typical audible range of a healthy human ear is 20 to 20,000 Hz.
A Sound ressure Level (SPL) beyond the detectable frequencies of the human ear can also be mportant to design engineers. Noise, Vibration and Harshness (NVH) is concerned with the study of vibration and audible sounds. Vibrations represent a rapid linear motion of a particle or of an elastic solid about an equilibrium position, or fluctuation of ressure level.
Harshness refers to the treatments of transient frequencies or shock. Usually treatments are employed to eliminate noise, but in some cases products are designed to magnify the sound and vibration at particular frequencies. The sound produced or received by a typical object, which may be above and below the frequencies that are detectable by the human ear, or amplitudes concerning its resonant frequencies, are important to designers, in order to characterize the items performance and longevity.
Technology Fundamentals and Microphone Types
When an object vibrates in the presence of air, the air molecules at the surface will begin to vibrate,which in turn vibrates the adjacent molecules next to them. This vibration will travel through the air as oscillating pressure at frequencies and plitudes determined by the original sound source. The human eardrum transfers these pressure oscillations, or sound, into electrical signals that are interpreted by our brains as music, speech, noise, etc.
Microphones are designed, like the human ear, to transform pressure oscillations into electrical signals, which can be recorded and analyzed to tell us information about the original source of vibration or the nature of the path the sound took from the source to the microphone. This is exhibited in testing of noise reducing materials.
Pressure from sound must be analyzed in the design stages to not only protect the materials around it, but also to protect the most precious and delicate mechanism designed to perceive it, the human ear. Like the human ear,microphones are designed to measure a very large range of amplitudes, typically measured in decibels (dB) and frequencies in hertz (Hz.) In order to convert acoustical energy into electrical energy, microphones are used.
There are a few different designs for microphones. The more common designs are Carbon Microphones, Externally Polarized Condenser Microphones, Prepolarized Electret Condenser Microphones, Magnetic Microphones, and Piezoelectric Microphones. The carbon microphone design is a value-oriented design. This design is a very low quality acoustic transducer type. An enclosure is built.
This enclosure houses lightly packed carbon granules. At opposite ends of the enclosure, electrical contacts are placed, which have a measured resistance. When the pressure from an acoustical signal is exerted on the microphone, it forces the granules closer together. This force presses the granules together, which decreases the resistance. This change inresistance is measured and output. A typical use of this item can be seen in early basic designs of a telephone handset. A condenser microphone operates on a capacitive design.
The cartridge from the condenser microphone utilizes basic transduction principles and will transform the sound pressure to capacitance variations, which are then converted to an electrical voltage. This is accomplished by taking a small thin diaphragm and stretching it a small distance away from a stationary metal plate, called a “backplate.” A voltage is applied to the backplate to form a capacitor. In the presence of oscillating pressure, the diaphragm will move which changes the gap between the diaphragm and the backplate.
This produces an oscillating voltage from the capacitor, proportional to the original pressure.The backplate voltage can be generated by two different methods. The first is an externally polarized microphone design where an external power supply is used. The power source on this traditional design is 200 volts. The second or newer design is called a prepolarized microphone design. This modern design utilizes an “electret” layer placed on the backplane, which contains charged particles that supply the polarization.
This design, when coupled with an Integrated Circuit Piezoelectric (ICP) circuit can provide great advantages. An inexpensive constant current supply can power the unit, instead of the more expensive externally polarized power supplies. Standard coaxial cables with BNC or 10-32 connectors can be used, instead of LEMO 7-pin connectors and cables. Latest Microphone Technology
The coaxial cables can be driven long distances without degradation of the signal. The modern prepolarized designs are becoming increasingly popular for laboratory test and measurement, and field applications, due to their low cost and ease of use. A magnetic microphone is a dynamic microphone.
The moving coil design is based on the principal of magnetic induction. This design can be simply achieved by attaching a coil of wire to a light diaphragm. Upon seeing the acoustical pressure, the coil will move. When the wire is subjected to the magnetic field, the movement of the coil in the magnetic field creates a voltage, which is proportional to the pressure exerted on it.
A Piezoelectric microphone uses a quartz or manmade ceramic crystal structure, which are similar to
electrets in that they exhibit a permanent polarization and can be coupled with an ICPdesign. Although these sensor type microphones have very low sensitivity levels, they are very durable and are able to measure very high amplitude (decibels) pressure ranges. Latest Microphone Technology - Conversely, the floor noise level on this type of microphone is generally very high. This design is suitable for shock and blast pressure measurement applications.The most popular test and measurement microphones are the capacitor condenser designs.
A Sound ressure Level (SPL) beyond the detectable frequencies of the human ear can also be mportant to design engineers. Noise, Vibration and Harshness (NVH) is concerned with the study of vibration and audible sounds. Vibrations represent a rapid linear motion of a particle or of an elastic solid about an equilibrium position, or fluctuation of ressure level.
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Technology Fundamentals and Microphone Types
When an object vibrates in the presence of air, the air molecules at the surface will begin to vibrate,which in turn vibrates the adjacent molecules next to them. This vibration will travel through the air as oscillating pressure at frequencies and plitudes determined by the original sound source. The human eardrum transfers these pressure oscillations, or sound, into electrical signals that are interpreted by our brains as music, speech, noise, etc.
Microphones are designed, like the human ear, to transform pressure oscillations into electrical signals, which can be recorded and analyzed to tell us information about the original source of vibration or the nature of the path the sound took from the source to the microphone. This is exhibited in testing of noise reducing materials.
Pressure from sound must be analyzed in the design stages to not only protect the materials around it, but also to protect the most precious and delicate mechanism designed to perceive it, the human ear. Like the human ear,microphones are designed to measure a very large range of amplitudes, typically measured in decibels (dB) and frequencies in hertz (Hz.) In order to convert acoustical energy into electrical energy, microphones are used.
Latest Microphone Technology
There are a few different designs for microphones. The more common designs are Carbon Microphones, Externally Polarized Condenser Microphones, Prepolarized Electret Condenser Microphones, Magnetic Microphones, and Piezoelectric Microphones. The carbon microphone design is a value-oriented design. This design is a very low quality acoustic transducer type. An enclosure is built.
This enclosure houses lightly packed carbon granules. At opposite ends of the enclosure, electrical contacts are placed, which have a measured resistance. When the pressure from an acoustical signal is exerted on the microphone, it forces the granules closer together. This force presses the granules together, which decreases the resistance. This change inresistance is measured and output. A typical use of this item can be seen in early basic designs of a telephone handset. A condenser microphone operates on a capacitive design.
The cartridge from the condenser microphone utilizes basic transduction principles and will transform the sound pressure to capacitance variations, which are then converted to an electrical voltage. This is accomplished by taking a small thin diaphragm and stretching it a small distance away from a stationary metal plate, called a “backplate.” A voltage is applied to the backplate to form a capacitor. In the presence of oscillating pressure, the diaphragm will move which changes the gap between the diaphragm and the backplate.
This produces an oscillating voltage from the capacitor, proportional to the original pressure.The backplate voltage can be generated by two different methods. The first is an externally polarized microphone design where an external power supply is used. The power source on this traditional design is 200 volts. The second or newer design is called a prepolarized microphone design. This modern design utilizes an “electret” layer placed on the backplane, which contains charged particles that supply the polarization.
This design, when coupled with an Integrated Circuit Piezoelectric (ICP) circuit can provide great advantages. An inexpensive constant current supply can power the unit, instead of the more expensive externally polarized power supplies. Standard coaxial cables with BNC or 10-32 connectors can be used, instead of LEMO 7-pin connectors and cables. Latest Microphone Technology
The coaxial cables can be driven long distances without degradation of the signal. The modern prepolarized designs are becoming increasingly popular for laboratory test and measurement, and field applications, due to their low cost and ease of use. A magnetic microphone is a dynamic microphone.
The moving coil design is based on the principal of magnetic induction. This design can be simply achieved by attaching a coil of wire to a light diaphragm. Upon seeing the acoustical pressure, the coil will move. When the wire is subjected to the magnetic field, the movement of the coil in the magnetic field creates a voltage, which is proportional to the pressure exerted on it.
A Piezoelectric microphone uses a quartz or manmade ceramic crystal structure, which are similar to
electrets in that they exhibit a permanent polarization and can be coupled with an ICPdesign. Although these sensor type microphones have very low sensitivity levels, they are very durable and are able to measure very high amplitude (decibels) pressure ranges. Latest Microphone Technology - Conversely, the floor noise level on this type of microphone is generally very high. This design is suitable for shock and blast pressure measurement applications.The most popular test and measurement microphones are the capacitor condenser designs.
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