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STUDENT TRAINER:SUMITSTUDENT TRAINER:SUMITCLASS : 9CLASS : 9THTH

Delhi Public School, RanchiDelhi Public School, Ranchi

BY:

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CONTENTSCONTENTS

INTRODUCTIONINTRODUCTION

TYPESTYPES

WORKINGWORKING PROPERTIESPROPERTIES

SOUND SYSTEMSOUND SYSTEM

RESULTRESULT ACKNOWLEDGMENTACKNOWLEDGMENT

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INTRODUCTIONINTRODUCTION

Audio means "of sound" or "of theAudio means "of sound" or "of thereproduction of sound". Specifically, it refers toreproduction of sound". Specifically, it refers tothe range of frequencies detectable by thethe range of frequencies detectable by thehuman ear (approximately 20Hz to 20 kHz).human ear (approximately 20Hz to 20 kHz).

Audio work involves the production,Audio work involves the production,manipulation, recording, and reproduction ofmanipulation, recording, and reproduction ofsound waves. To be able to understand audio,sound waves. To be able to understand audio,you must have a good understanding of twoyou must have a good understanding of twothings:things:

Sound Waves: What they are, how they areSound Waves: What they are, how they are

produced and how we hear them.produced and how we hear them. Sound Equipment: What the differentSound Equipment: What the different

components are, what they do, how to choosecomponents are, what they do, how to choosethe correct equipment and use it properly.the correct equipment and use it properly.

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TYPESTYPES The field of audio is vast, with many areas ofThe field of audio is vast, with many areas of

specialty. Hobbyists use audio for all sorts ofspecialty. Hobbyists use audio for all sorts ofthings, and audio professionals can be found inthings, and audio professionals can be found ina huge range of vocations. Some common areasa huge range of vocations. Some common areasof audio work include:of audio work include:

Studio Sound EngineerStudio Sound Engineer

Live Sound EngineerLive Sound Engineer

MusicianMusician Music ProducerMusic Producer DJDJ Radio technicianRadio technician

Film/Television Sound RecordistFilm/Television Sound Recordist Field Sound EngineerField Sound Engineer Audio EditorAudio Editor Post-Production Audio CreatorPost-Production Audio Creator

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WORKINGWORKING

Sound waves travel through air inSound waves travel through air in

much the same way as water wavesmuch the same way as water waves

travel through water. In fact, sincetravel through water. In fact, since

water waves are easy to see andwater waves are easy to see and

understand, they are often used asunderstand, they are often used as

an analogy to illustrate how soundan analogy to illustrate how sound

waves behave.waves behave.

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In the diagram below, the black dots represent air

molecules. As the loudspeaker vibrates, it causes the

surrounding molecules to vibrate in a particular

pattern represented by the waveform. The vibrating

air then causes the listener's eardrum to vibrate in thesame pattern. Viola - Sound!

Variations in Air Pressure and Corresponding

Waveform

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PROPERTIES OF WAVESPROPERTIES OF WAVES Wave PropertiesWave Properties

All waves have certain properties - three importantAll waves have certain properties - three importantones are shown here:ones are shown here:

Wavelength:Wavelength: The distance between any point on aThe distance between any point on awave and the equivalent point on the next phase.wave and the equivalent point on the next phase.Literally, the length of the wave.Literally, the length of the wave.

Amplitude:Amplitude: The strength or power of a wave signal.The strength or power of a wave signal.The "height" of a wave when viewed as a graph.The "height" of a wave when viewed as a graph. Higher amplitudes are interpreted as a higher volume -Higher amplitudes are interpreted as a higher volume -

hence the name "amplifier" for a device whichhence the name "amplifier" for a device whichincreases amplitude.increases amplitude.

Frequency:Frequency: The number of times the wavelengthThe number of times the wavelength

occurs in one second. Measured in kilohertz (Khz), oroccurs in one second. Measured in kilohertz (Khz), orcycles per second. The faster the sound sourcecycles per second. The faster the sound sourcevibrates, the higher the frequency.vibrates, the higher the frequency.

Higher frequencies are interpreted as a higher pitch.Higher frequencies are interpreted as a higher pitch.For example, when you sing in a high-pitched voiceFor example, when you sing in a high-pitched voice

you are forcing your vocal chords to vibrate quicklyyou are forcing your vocal chords to vibrate quickly

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HOW SOUND WAVESHOW SOUND WAVES

INTEREACT WITH EACH OTHERINTEREACT WITH EACH OTHER When different waves collide (e.g. sound fromWhen different waves collide (e.g. sound from

differentdifferent sources) they interfere with each other.sources) they interfere with each other.This is called, unsurprisingly,This is called, unsurprisingly, wave interferencewave interference..

PhasingPhasing The following table illustrates how sound waves (orThe following table illustrates how sound waves (or

any other waves) interfere with each otherany other waves) interfere with each otherdepending on their phase relationship:depending on their phase relationship: Sound waves which are exactly in phase addSound waves which are exactly in phase add

together to produce a stronger wave.together to produce a stronger wave. Sound waves which are exactly 180 degrees out ofSound waves which are exactly 180 degrees out of

phase cancel each other out and produce silencephase cancel each other out and produce silence(this is how many noise-cancellation devices work).(this is how many noise-cancellation devices work).

Sound waves which have varying phase relationshipsSound waves which have varying phase relationshipsproduce differing sound effectsproduce differing sound effects

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SOUND SYSTEMSOUND SYSTEM Working with audio means working with sound systems.Working with audio means working with sound systems.

Naturally, the range of systems available for differentNaturally, the range of systems available for differentapplications is enormous. However, all electronic audioapplications is enormous. However, all electronic audiosystems are based around one very simple concept: Tosystems are based around one very simple concept: Totake sound waves, convert them into an electric currenttake sound waves, convert them into an electric currentand manipulate them as desired, then convert them backand manipulate them as desired, then convert them backinto sound waves.into sound waves.

A very simple sound system is shown in the diagramA very simple sound system is shown in the diagrambelow. It is made up of two types of component:below. It is made up of two types of component:

TransducerTransducer - A device which converts energy from one- A device which converts energy from oneform into another. The two types of transducers we willform into another. The two types of transducers we willdeal with are microphones (which convert acousticaldeal with are microphones (which convert acousticalenergy into electrical energy) and speakers (which convertenergy into electrical energy) and speakers (which convert

electrical energy into acoustical energy).electrical energy into acoustical energy). AmplifierAmplifier - A device which takes a signal and increases- A device which takes a signal and increases

it's power (i.e. it increases the amplitudeit's power (i.e. it increases the amplitude

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WORKINGWORKING

The next diagram shows a slightly more elaborateThe next diagram shows a slightly more elaboratesystem, which includes:system, which includes:

Signal processorsSignal processors- devices and software which- devices and software whichallow the manipulation of the signal in variousallow the manipulation of the signal in various

ways. The most common processors are tonalways. The most common processors are tonaladjusters such as bass and treble controls.adjusters such as bass and treble controls.

Record and playback sectionRecord and playback section- devices which- devices whichconvert a signal to a storage format for laterconvert a signal to a storage format for laterreproduction. Recorders are available in manyreproduction. Recorders are available in manydifferent forms, including magnetic tape, opticaldifferent forms, including magnetic tape, opticalCD, computer hard drive, etc.CD, computer hard drive, etc.

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DIAGRAMDIAGRAM

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RESULTRESULT

The audio signal from the transducerThe audio signal from the transducer(microphone) is passed through one(microphone) is passed through oneor more processing units, whichor more processing units, whichprepare it for recording (or directlyprepare it for recording (or directlyfor amplification).for amplification).

The signTal is fed to a recordingThe signTal is fed to a recordingdevice for storage.device for storage.

The stored signal is played back andThe stored signal is played back andfed to more processors.fed to more processors.

The signal is amplified and fed to aThe signal is amplified and fed to aloudspeakerloudspeaker

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ACKNOWLEDGMENTACKNOWLEDGMENT

WE ARE THANKUL TO OUR TEACHERWE ARE THANKUL TO OUR TEACHER

WHO HELP US IN COMPLETING THISWHO HELP US IN COMPLETING THIS

PROJECT.PROJECT.

THANKSTHANKS