Sound

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Sound

• Chapter 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

• 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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MIDI

• 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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MIDI

• 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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MIDI

• 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 cant save a human
  voice or an explosion

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Video

• 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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Applications

• 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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Speakers

• 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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Jacks

• 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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Speaker Standards

• 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

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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

• 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
• Dont 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 XPs 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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Drivers

• 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 manufacturers web site for updates
• Check Device Manager

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Speakers

• Make sure they are on and getting power
• Make sure they are plugged in right
• Check the volume control settings

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Application

• 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
• Theres a benchmark utility available called
  AudioWinBench
• www.veritest.com/benchmarks/winbench/winbench.asp

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