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SoundChapter 1: Part 13

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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

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How Sound Works in a PC

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Sound-Capture Basics

• Four components for capturing and outputting sound1. Sound card2. Speakers3. Microphone4. Recording/Playback software

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Sound-Capture Basics

• Sampling—capturing sound

– Sampling rate is measured in cycles per second (KHz)

• Low quality (11 KHz) to high quality (192 KHz)

– Doesn’t capture every nanosecond of sound

– Takes samples and extrapolates, or predicts, what the data is between samples

• Dotted line—can you connect the dots?

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Sound-Capture Basics

• Sampling—capturing sound

– Bit depth—Number of characteristics of a particular sound (for each sample)

• Amplitude (loudness)

• Frequency (tone)

• Timbre (qualities from different instruments)

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Sound-Capture Basics

• Waveforms are commonly sampled with either 8 or 16 bits per sample– 8-bit stores 28 or 256 different characteristics– 16-bit stores 216 or 65,536 different characteristics

• Tracks– Monaural—one track– Stereo—two tracks

• CD quality– 44.1 KHz– 16 bit depth

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Recorded Sound Formats

• Pulse code modulation (PCM)– Developed for telephone calls

– Better known as the WAV format

– Large files• Four-minute song at 44.1 KHz and 16-bit stereo is greater

than 40 MB

– Compressor/decompressor (CODEC) programs• Algorithms developed to compress sound files• MPEG-1 Layer 3 codec or MP3 is one example of a codec

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Playing Sounds

• Every sound card can play WAV files using sound player software– Windows Media Player comes with Windows– iTunes is Apple’s media program– Many other good sound players are available

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MIDI

• Musical Instrument Digital Interface – MIDI file is a text file

• Contain a series of commands that describe– What note to play– How long to play it– Which instruments to use

• Tiny in size compared to WAV files– Beethoven’s Fifth Symphony is 78 MB as a WAV file

and 60 KB as a MIDI file

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MIDI

• Sound cards play MIDI files using one of two technologies

1. FM synthesis• Strictly electronic—software says what to play

2. Wave table synthesis• Uses recorded sounds (WAV files) to start• Modifies characteristics of sounds to create

amplitude, frequency, and timbre desired• Polyphony of card—how many instruments it can

play at once (128 instruments is common)

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Other File Formats

• Over 100 sound formats– Table lists just a few

Acronym DescriptionAAC Advanced Audio Coding—native format for Apple’s

iTunesAIFF Audio Interchange File Format—popular with

Macintosh computersASX Microsoft Advanced Streaming RedirectorAU Can be played in Windows, Sun, Next, UNIX and

MacintoshOGG Vorbis format—open source codexRM RealMedia—audio, or audio and videoWMA Windows Media Audio—proprietary

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Video

• Videos typically have sound built in– Some common video formats are

Acronym DescriptionAVI Audio Video InterleaveMPEG Moving Pictures Experts GroupMOV QuickTimeASF Advanced Streaming FormatRM Real Media

WMV Windows Media VideoDivX Often used for ripping audio and videoFlash Used on YouTube

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Applications

• Many applications (especially games) 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• Apple’s iTunes

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CompTIA A+Essentials

Essentials

Getting the Right Sound CardGetting the Right Sound Card

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Sound Cards

• A sound card typically has many built-in features– Two separate processors (one for MIDI and one for

the rest)– Support chips for joysticks– Recording capabilities– MIDI support– More

• Can be a separate sound card– Often just a chip built in to the motherboard

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• Sound cards differ in five basic areas:- Processor capabilities - Speaker support- Recording quality - Jacks- Extra features

• Processor handles communication between the application, OS, 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 and provides better sound quality

Sound Card Differences

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Sound Card Differences

• Speaker support– Basic support—two

speakers or headphones– Better sound cards support

five or more speakers– Often have a subwoofer– 5.1 means 5 speakers with 1 subwoofer

• Recording quality– Signal-to-noise (S/N) ratio expressed in decibels– Low end have S/N ratio of 30 to 50 decibels

• Records artifacts (noise) when there is no actual noise

– High-end cards offer a 96 to 100+ S/N ratio

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Sound Card Differences

• Jacks– Line In and Line Out converters enable the sound

card to send and receive input and output from other devices

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

– Rear Out connects to the 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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Sound Card Differences

• Extra Features– Almost all motherboards have built-in sound– Extra goodies needed to entice buyers– Digital output to integrate PC with home

entertainment system– DVD receiver– Surround-sound speaker connections– Breakout box adding ports to front of PC– More

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Audio Cables

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

– Most optical 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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Surround-Sound Standards

• Dolby Digital– Supports five channels plus subwoofer (5.1)– Front right, front left, front center, rear left, rear right

• Digital Theatre System (DTS)– Competing standard that also supports 5.1

• Sony/Philips Digital Interface (S/PDIF) – Uses single connector for entire 5.1 system

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Surround-Sound Standards

• DirectX provides applications, primarily games, with direct access to hardware– Offers developers easy-to-use commands– Easy to program sounds in the desired channel

• DirectSound3D (DS3D)– Can place a sound anywhere in 3D space – Known as positional audio

• Environmental audio extensions (EAX)– Creative Labs’ response to DS3D

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Speaker Features

• Controls– Volume controllers– On/off switch– Can be on speakers

or on special box

• Headphone jack– Some systems

can automaticallysense when plugged in

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Installing a Sound Card in a Windows System

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Physical Installation

• Installs like any other PCI card– Plug in the card– Load the drivers– Test

• Hardest part may be identifying where to plug in speakers– Refer to documentation– Typical stereo or 2.1 speaker system plugs into

Speaker or Speaker 1 port– Surround-sound speakers use single S/PDIF

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• Basic steps– Shut down your computer, unplug it, and open

the case– Find an open PCI slot and install card– Connect the CD audio cable to the drive and

the card

Physical Installation

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Installing Drivers

• Let Windows install drivers– If necessary/desired, use CD

that came with sound card

• If installing a USB sound card– Follow the cardinal rule for USB drivers:

Install the USB driver before the USB device

• Verify driver is installed by checking Device Manager

• Test

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Configuration Applications

• Most sound card configurations can be done within Windows

– Use the Sounds and Audio Devices applet in Windows XP’s Control Panel

– Or Sounds and Multimedia in Windows 2000

– Five tabs• Volume• Sounds• Audio• Voice• Hardware

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Proprietary Configuration Apps

• Many sound cards install proprietary software

– Adds access to other features that aren’t otherwise available

– Autosensing—allows hardware to be plugged in using different ports and the ports adjust

• Plug microphone into speaker port and speaker port becomes a microphone port

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Installing Applications

• Some sound cards install extra software

– Goal is to provide user with extra free software

– These programs aren’t needed to use any of the features

– Intended to provide extra value for the purchase

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IT Technician

CompTIA A+Technician

Troubleshooting Sound

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Hardware Problems

• Volume– Check physical controls– Check software controls

• Windows Volume controls

• Speakers– Ensure they are turned on and getting good power– Make sure they are plugged in– Check for visual indicators that a sound is playing

• Replace speakers if blown speakers suspected

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Configuration Problems

• First place to check: Device Manager– Consider reinstalling driver

• Ensure the latest device drivers are installed– Check the manufacturer’s

Web site for updates

• Review the Sounds and Audio Devices applet settings

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Application Problems

• First, look for an error message– Check the application’s

support site

• Second, check the sound file– Sound files might be corrupted

• Last, reinstall the application

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Beyond A+

• Sound card benchmarking

– PC performance issues may be related to your sound card

– Analyze your sound card with RightMark 3DSound from iXBT.Com/Digit-Life

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