Download Multimedia notes unit 4 and more Summaries IP Multimedia Subsystems in PDF only on Docsity!
Name of the Faculty Dr^ C.Sathya Department Computer^ Technology Designation Assistant Professor Name of the Course MULTIMEDIA Semester VI Course Code 63A Batch 2025 Unit & Course Topic (^) AUDIO: Introduction – Acoustics- Nature of sound waves- Fundamental characteristics of sound- Amplifier- Loudspeaker- Audio mixer- Digital Audio- Synthesizers- MIDI-Basics of staff Notation- Sound card- Audio transmission- Audio file formats and CODECs- Audio Recording systems- Audio & Multimedia- Voice Recognition and Response- Audio processing software 1
UNIT-IV
SYLLABUS
AUDIO: Introduction – Acoustics- Nature of sound waves- Fundamental characteristics of sound- Amplifier- Loudspeaker- Audio mixer- Digital Audio- Synthesizers- MIDI-Basics of staff Notation- Sound card- Audio transmission- Audio file formats and CODECs- Audio Recording systems- Audio & Multimedia- Voice Recognition and Response- Audio processing software
ACOUSTICS
- Acoustics is the interdisciplinary science that deals with the study of all mechanical
- waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound.
- A scientist who works in the field of acoustics is an acoustician while someone working
- in the field of acoustics technology may be called an acoustical or audio engineer.
- The application of acoustics can be seen in almost all aspects of modern society with the most obvious being the audio and noise control industries.
- Acoustics is the branch of science dealing with the study of sound and is concerned with the generation, transmission and reception of sound waves.
- The application of acoustics in technology in technology is
called acoustical engineering.
NATURE OF SOUND WAVES
- Sound is one kind of longitudinal wave, in which the particles oscillate to and fro in the same direction of wave propagation. Sound waves cannot be transmitted through vacuum.
- The transmission of sound requires at least a medium, which can be solid, liquid, or gas.
- Acoustics is the branch of science dealing with the study of sound and is concerned with the generation.
- The application of acoustics in technology is called acoustical engineering.
REPRESENTATION OF SOUND WAVES
- The distinction between noise and tone is based on the regularity of the vibrations, the degree of damping, and the ability of the ear to recognize components having a musical sequence.
- On compression the frequency of sound increases and it appears more high-pitched to our ears,while on expansion ,the frequency decreases making it appear more dull and flat.
- This is known as Doppler Effect
AMPLITUDE
- Amplitude of wave is the maximum displacement of a particle in the path of a wave and is measure of the peak- to - peak height of the wave.
- The physical manifestation of amplitude is the intensity of energy of the wave.
- Loudness is measured in a unit called decibel denoted by dB.
WAVEFORM
- It indicates the actual shape of the wave when represented pictorially. Shapes of waves can be sinusoidal, square, triangular, sawtooth etc.
- The physical manifestation of waveform is the quality or timbre of sound.
- Two sounds having the same loudness and pitch but having different waveform will have different hearing perceptions in our ears.
SPEED
- The speed of sound depends on the medium through which the sound travels,and the temperature of medium but not on the pressure.
- The speed is about 340m/sec in air and 1500m/sec in water.
DYNAMIC MICROPHONE
- A moving coil microphone consists of a thin metallic diaphragm and an attached coil of wire.
- A magnet produces a magnetic field which surrounds the coil.
- In the magneto-dynamic, commonly called dynamic, microphone, sound waves cause movement of a thin metallic diaphragm and an attached coil of wire.
- A magnet produces a magnetic field which surrounds the coil, and motion of the coil within this field causes current to flow.
- It is important to remember that current is produced by the motion of the diaphragm, and that the amount of current is determined by the speed of that motion.
- This kind of microphone is known as velocity sensitive.
- The amount of current is essentially proportional to the displacement of the diaphragm, and is so small that it must be electrically amplified before it leaves the microphone.
- A common variant of this design uses a material with a permanently imprinted charge for the diaphragm.
- Such a material is called an electret and is usually a kind of plastic.
- Plastic is a pretty good material for making diaphragms since it can be dependably produced to fairly exact specifications.
