Sound - PowerPoint PPT Presentation

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Sound Chapter 13 Overview In this chapter, you will learn to Describe how sound works in a PC Select the appropriate sound card for a given scenario Install a sound card in a Windows system Troubleshoot problems that might arise with sound cards and speakers How Sound Works in a PC

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Chapter 13

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  • In this chapter, you will learn to

    • Describe how sound works in a PC

    • Select the appropriate sound card for a given scenario

    • Install a sound card in a Windows system

    • Troubleshoot problems that might arise with sound cards and speakers

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How Sound Works in a PC

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Sound-Capture Basics

  • Sound can be visualized as a constantly changing series of frequencies, which can be graphed as a waveform

  • The PC turns the waveform into a digital file by taking samples at regular intervals

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Sound-Capture Basics

  • The quality of recorded sound is based on the number of bits used for each sample, and how often the sound is sampled

  • Waveforms are commonly sampled with either 8 or 16 bits per sample

    • 8-bit stores 28 or 256 different frequencies

    • 16-bit stores 216 or 65,536 different frequencies

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Sound-Capture Basics

  • The sampling rate for a digital waveform is measured in thousands of time per second or kilohertz (KHz)

  • The more samples per second, the higher the quality of recorded sound

  • Waveforms are sampled in individual tracks

    • Monaural in one track

    • Stereo in two tracks

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Sound-Capture Basics

  • Waveforms are recorded at different…

    • Bit depths: 8-bit or 16-bit

    • Sample rates: 11 to 44 KHZ

    • Numbers of tracks: monaural, stereo or more

  • The WAV format for Windows provides a maximum of 16-bit sampling at 44 KHz on two tracks

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Recorded Sound Formats

  • Pulse code modulation (PCM)

    • Better known as the WAV format

    • Large files

      • 10 MB per minute for 16-bit stereo sampled at 44 KHz

    • Compressor/decompressor (CODEC) programs

      • Algorithms developed to compress sound files

      • MPEG-1 Layer 3 codec or MP3

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Playing Sounds

  • Every sound card can play WAV files using a sound player software

    • Media Player comes with Windows

    • Many other good sound players are available

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  • Musical Instrument Digital Interface (MIDI)

    • Second most popular type of sound on a PC

    • Designed to enable musicians to create, store, and play a broad cross section of instruments, including instruments invented on synthesizers

    • Sound card that has built-in recordings of real musical instruments

    • More expensive sound cards have larger numbers of instruments and better quality recordings

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  • A MIDI file contains a series of commands that describe

    • What note to play

    • How long to play it

    • Which instruments to use

  • Each instrument is called a voice

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  • The number of different instruments a sound card can play simultaneously is called its polyphony

    • Most sound cards today have at least 32-voice polyphony

  • Sound cards use one of the two methods for storing musical instruments

    • FM synthesis

    • Wavetable synthesis (higher quality)

  • Great for storing music but can’t save a human voice or an explosion

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  • Video files have sound built into them

  • Most common video formats

    • Audio Video Interleaves (AVI)

    • Moving Pictures Experts Group (MPEG)

    • QuickTime (MOV)

    • Advanced Streaming Format (ASF)

    • RealMedia (RM)

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  • Many applications play sounds

  • Most use the standard WAV, MP3, or MIDI file formats

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Streaming Media

  • Broadcast of data that is played on your computer and immediately discarded

    • Internet radio stations

    • Most popular players are

      • Windows Media Player

      • Winamp

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Getting the Right Sound Card

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Sound Cards

  • A sound card takes waveforms or MIDI files as input and generates analog signals to speakers or to a recording device

  • A sound card has two complete sets of components to support both waveform and MIDI

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Functions of a Sound Card

  • Record and play waveform files

  • Record and play MIDI files

  • Enable recording from a microphone or auxiliary input (CD player, vinyl record, tape)

  • Assist in playing CD-ROMs from the CD drive

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Processor Capabilities

  • The sound processor handles the communication among the application, operating system, and CPU

    • Low-end sound cards let your CPU do most of the work

    • Better sound cards do most of the processing which accelerates the sound process

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  • The speaker connection enables the sounds to be output to speakers

    • The classic PC sound card/speaker configuration supports two speakers in a stereo configuration

  • Speakers connect to the system through a single mini audio connector

  • The sound card has a minimal amount of amplification and therefore speakers have built-in amplifiers powered by batteries or an AC adapter

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  • Line In and Line Out converters enable the sound card to send and receive input and output from devices other than the speaker or microphone

    • The Line In connector runs to a Line Out or Aux connector on the back of a stereo receiving system

    • The Line Out is also often connected to a stereo system

  • Rear Out connects to rear speakers for surround sound

  • Analog/Digital Out for external digital connections

  • Microphone & Joystick

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Sound Card Connections

  • Main stereo speaker is blue

  • Line out connector is green

  • Microphone connector is pink

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Recording Quality

  • Based on the signal-to-noise ratio

    • Low and mid range cards 30 to 50 decibels

    • High-end range 96 to100 decibels

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Audio Cables

  • To play audio CDs through your sound card requires a cable from your CD drive to the sound card

    • Most CD media drives come with an MPC2 audio cable for this purpose

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Speaker Standards

  • Stereo

    • Left and right

  • 2.1 systems

    • Pair of speakers called satellites and a subwoofer

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3D sound

Surround sound designed for music and movies that surrounds the listener with sound

3D sound on the PC

True 3-D sound (used in 3-D games) that enables programmers to make sounds directional

Speaker Standards

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Surround Sound

  • Uses multiple soundtracks with each one dedicated to a different speaker

  • There are three predominant types

    • Dolby Surround or Dolby Pro Logic

      • Uses four speakers

    • Dolby Digital

      • Up to six separate channels with its own speaker

      • “.1” describes the subwoofer (the low sounds you feel more than you hear)

    • Digital Theatre Systems (DTS)

      • Uses less compression than Dolby Digital and is a direct competitor

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  • DirectX provides applications, primarily games, with virtually complete direct access to the hardware

    • Use the proper version of DirectX for your application or game to work

    • The DirectX diagnostic tool can be used to determine the version of DirectX

      • Access the DirectX Diagnostic Tool from the Tools  Windows menu in Computer Management in Windows 2000

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Installing a Sound Card in a Windows System

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Physical Installation

  • Installs like any other PCI card

    • Connect the CD audio cable from your CD or DVD to the CD Audio port on the sound card

      • Usually there are three ports on the card for a CD drive, DVD drive, or modem

    • Connect the external wires

      • Stereo or 2.1 speaker systems usually have just one jack labeled speaker

      • Surround speakers have either one Sony/Phillips digital interface (SPDIF) connector to the subwoofer or separate wires for the front two speakers (Speaker 1), back two speakers (Speaker 2), and the subwoofer or center channel

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Multiple Audio Connectors

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Device Drivers

  • Sound cards, due to their multiple functions of waveform, MIDI, and possibly CD-ROM, have complicated device drivers

    • Don’t think of it as the sound card driver. Instead think of the device driver as 3 or more different device drivers: waveform driver, MIDI driver, CD-ROM controller driver, and so on

  • Most sound cards come with an easy installation program

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Device Manager

  • The Device manager displays the several functions of a sound card as separate devices.

    • OPL3 is a MIDI device

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Configuration Applications

  • Most or all of your sound card configuration can be done with the Sounds and Audio Devices applet in Windows XP’s Control Panel

    • Or Sounds and Multimedia in Windows 2000 and Me

    • Or the two applets, Sounds and Multimedia, in Windows NT and Windows 9x

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Configuration Applications

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Troubleshooting Sound

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Hardware Problems

  • These types of problems are easy to diagnose and are generally due to a faulty physical connection, volume control, etc.

    • Some older sound cards have a volume control wheel on the card itself, which should be adjusted for audible output

  • Crackling sounds coming from the speaker or in microphone recordings usually indicate bad wires

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  • The correct device driver needs to be configured for the proper functioning of a sound card

  • Ensure that the latest device drivers are installed

    • Check the manufacturer’s web site for updates

  • Check Device Manager

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  • Make sure they are on and getting power

  • Make sure they are plugged in right

  • Check the volume control settings

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  • An application that uses sound has its own set of configuration issues

  • Some applications, such as games, may require advanced sound features

  • See if you can get sound in Control Panel. If you can, then the problem lies in the application.

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Sound Card Benchmarking

  • PC performance issues may be related to your sound card

  • There’s a benchmark utility available called AudioWinBench


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