Download Microphone

VIDEO INPUT DEVICES;
! Scanners & 3D Scanners:
Scanner, device for examining an object in detail in order to
produce an electronic image of it, using visible light or another form of
electromagnetic radiation such as a laser.
Important Features.
! Medical use of scanning, see Magnetic
Resonance Imaging; Radiology; x ray: Medicine
! Reading text or images for the use of computers
see Digitize; Office Systems: Computers;
Facsimile Transmission; Optical Character
Recognition; Optical Scanner
! Scanning objects in space see Remote Sensing;
Lunar Orbiter: Spacecraft
! Other uses for scanners see Cash Register;
Commercial Photography: Equipment; Library:
Circulation Systems; Television: Scanning
!manufacturer of scanners, see Xerox Corporation
! Overview of computer input hardware, see
Computer: Input Devices; Hardware (computer):
Input Hardware
! CCD READER:
Charge-Coupled Device (CCD), sensitive electronic device that
stores packets of information as electric charge. Because of their versatility
in storing charge, CCDs are often used as analog-to-digital and digital-toanalog converters and signal scramblers, but their main function is recoding
information about light hitting the surface of the CCD to create light images
electronically.
A CCD used for recording visual information is made of an
array of photodiodes (devices that conduct electricity when light strikes
them) on top of a semiconductor (a material that conducts electricity better
than electrical insulators but not as well as electrical conductors). When
light strikes a photodiode, an electric current proportional to the amount of
light is sent to a capacitor, which stores the charge. The semiconductor
processes the signal from the capacitor and sends it to a computer or other
device that can analyze the data about the light that hit the CCD.
CCDs are used in facsimile machines, photocopiers (see
Xerography), bar-code readers, and cameras. In astronomy CCDs have
almost completely replaced photographic film as an image-capturing
method. A CCD is about a hundred times more sensitive to light than
photographic film or a photographic plate. The signal from a CCD is also
easier than a photographic image to convert into digital code for storage in
a computer.
! DIGITAL Web CAMERA:
Digital Camera is an input device. A
digital camera stores images digitally rather than
recording them on film. Once a picture has been
taken, it can be input or downloaded to your
computer where it is stored for later use. The
concept is the same whether you take a film photo
and then use your scanner as an input device or take
a photo with your digital camera and use the
camera itself as an input device. In both cases, the
image is input into the computer
Biometrics:
Biometrics in reference to biological sciences has been studied and
applied for several generations and is somewhat simply viewed as
"biological statistics."
More recently and incongruently, the term's meaning has been broadened to
include the study of methods for uniquely recognizing humans based upon
one or more intrinsic physical or behavioral traits.
Barcode reader
A barcode reader (or barcode scanner) is an electronic device for
reading printed barcodes. Like a flatbed scanner, it consists of a light
source, a lens and a photo conductor translating optical impulses into
electrical ones. Additionally, nearly all barcode readers contain decoder
circuitry analyzing the barcode's image data provided by the photo
conductor and sending the barcode's content to the scanner's output port.
AUDIO INPUT DEVICES:
Here is a brief detail of audio input devices.
! MICROPHONE;
Microphone:
A microphone sometimes referred to as a mike or mic is an acoustic-toelectric transducer or sensor that converts sound into
an electrical signal.
Microphones are used in many applications such as
telephones, tape recorders, hearing aids, motion
picture production, live and recorded audio
engineering, in radio and television broadcasting and
in computers for recording voice, VoIP, and for nonacoustic purposes such as ultrasonic checking
Principle of operation:
Edmund Lowe using a microphone
A microphone is a device made to capture waves in air,
water (hydrophone) or hard material and translate them
into an electrical signal. The most common design uses
a thin membrane which vibrates in response to sound
pressure, this movement being subsequently translated into an electrical
signal. Most microphones in use today for audio use electromagnetic
generation (dynamic microphones), capacitance change (condenser
microphones) or piezoelectric generation to produce the signal from
mechanical vibrMicrophone, device used to transform sound energy into
electrical energy (see Sound Recording and Reproduction). Microphones
are important in many kinds of communications systems and in instruments
that measure sound and noise. The American inventor Alexander Graham
Bell built the first microphone in 1876 when he constructed his telephone
spreader.
Types:
Carbon microphones
Ribbon microphones
Moving coil microphones
Dynamic microphones
Electrets condenser microphones
! Unidirectional:
A unidirectional microphone is sensitive to sounds from only one
direction. The diagram above illustrates a number of these patterns. The
microphone faces upwards in each diagram. The sound intensity for a
particular frequency is plotted for angles radically from 0 to 360°.
(Professional diagrams show these scales and include multiple plots at
different frequencies. These diagrams just provide an overview of the typical
shapes and their names.)
! Shotgun:
Shotgun microphones are the most
highly directional. They have small lobes of
sensitivity to the left, right, and rear but are
significantly more sensitive to the front. This
results from placing the element inside a tube
with slots cut along the side; wave-cancellation eliminates most of the offaxis noise. Shotgun microphones are commonly used on TV and film sets,
and for field recording of wildlife.
An Omni directional microphone is a pressure transducer; the output
voltage is proportional to the air pressure at a given time.
On the other hand, a figure-8 pattern is a pressure gradient transducer; a
sound wave arriving from the back will lead to a signal with a polarity
opposite to that of an identical sound wave from the front. Moreover, shorter
wavelengths (higher frequencies) are picked up more effectively than lower
frequencies.
A cardioids microphone is effectively a superposition of an Omni directional
and a figure-8 microphone; for sound waves coming from the back, the
negative signal from the figure-8 cancels the positive signal from the Omni
directional element, whereas for sound waves coming from the front, the two
add to each other. A hyper cardioids microphone is similar, but with a
slightly larger figure-8 contribution.
Since pressure gradient transducer microphones are directional, at
distances of a few centimeters of the sound source results in a bass boost.
This is known as the proximity effect.
Application-specific microphone designs:
A lavaliere microphone is made for hands-free operation. These
small microphones are worn on the body and held in place either with a
lanyard worn around the neck or a clip fastened to clothing. The cord may
be hidden by clothes and either run to an RF transmitter in a pocket or
clipped to a belt (for mobile use), or run directly to the mixer (for stationary
applications).
! Wireless microphone
A wireless microphone is one which does not use a cable. It
usually transmits its signal using a small FM radio transmitter to a nearby
receiver connected to the sound system, but it can also use infrared light if
the transmitter and receiver are within sight of each other.
! Contact microphone:
A contact microphone is designed to pick up vibrations directly
from a solid surface or object, as opposed to sound vibrations carried
through air. One use for this is to detect sounds of a very low level, such as
those from small objects or insects. The microphone commonly consists of a
magnetic (moving coil) transducer, contact plate and contact pin. The
contact plate is placed against the object from which vibrations are to be
picked up; the contact pin transfers these vibrations to the coil of the
transducer. Contact microphones have been used to pick up the sound of a
snail's heartbeat and the footsteps of ants. A portable version of this
microphone has recently been developed.
! Throat microphone
A throat microphone is a variant of the contact microphone, used
to pick up speech directly from the throat, around which it is strapped. This
allows the device to be used in areas with ambient sounds that would
otherwise make the speaker inaudible.
! Parabolic microphone
Parabolic microphone uses a parabolic reflector to collect and
focus sound waves onto a microphone receiver, in much the same way that a
parabolic antenna (e.g. satellite dish) does with radio waves. Typical uses of
this microphone, which has unusually focused front sensitivity and can pick
up sounds from many meters away, include nature recording, outdoor
sporting events, eavesdropping, law enforcement, and even espionage.
Parabolic microphones are not typically used for standard recording
applications, because they tend to have poor low-frequency response as a
side effect of their design.
Speech recognition:
Speech recognition (also known as automatic speech recognition
or computer speech recognition) converts spoken words to machinereadable input (for example, to the binary code for a string of character
codes). The term voice recognition may also be used to refer to speech
recognition, but more precisely refers to speaker recognition, which
attempts to identify the person speaking, as opposed to what is being said.
Speech recognition applications include voice dialing (e.g., "Call
home"), call routing (e.g., "I would like to make a collect call"), demotic
appliance control and content-based spoken audio search (e.g., find a pod
cast where particular words were spoken), simple data entry (e.g., entering
a credit card number), preparation of structured documents (e.g., a
radiology report), speech-to-text processing (e.g., word processors or
emails), and in aircraft cockpits (usually termed Direct Voice Input).
Applications:
Health care
High performance fighter aircraft
Helicopters
Battle management
Training air traffic controllers
Telephony and other domains
Disabled people
Automatic translation
Automotive speech recognition (e.g., Ford Sync)
Court reporting (Real-time Voice Writing)
Speech Biometric Recognition
Hands-free computing: voice command recognition computer user
interface
Home automation
Medical transcription
Mobile telephony, including mobile email
Multimodal interaction
Pronunciation evaluation in computer-aided language learning
applications