Overview
Sound
• In this part, 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
Sound-Capture Basics
How Sound Works in a PC
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
• 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
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
– 8-bit stores 28 or 256 different frequencies
– 16-bit stores 216 or 65,536 different frequencies
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Sound-Capture Basics
Recorded Sound
Formats
• Waveforms are recorded at different…
• Pulse code modulation (PCM)
– Bit depths: 8-bit or 16-bit
– Sample rates: 11 to 44 KHZ
– Numbers of tracks: monaural, stereo or more
– Better known as the WAV format
– Large files
• 10 MB per minute for 16-bit stereo sampled at 44 KHz
• The WAV format for Windows provides a
maximum of 16-bit sampling at 44 KHz
on two tracks
– Compressor/decompressor (CODEC) programs
Playing Sounds
MIDI
• Every sound card can play WAV files
using a sound player software
– Media Player comes with Windows
– Many other good sound players are available
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
• Algorithms developed to compress sound files
• MPEG-1 Layer 3 codec or MP3
• 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
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 can’t 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, RMVB)
Applications
• Many applications play sounds
• Most use the standard WAV, MP3, or
MIDI file formats
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
Getting the Right Sound Card
Sound Cards
Functions of a Sound
Card
• 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
1. Record and play waveform files
2. Record and play MIDI files
3. Enable recording from a microphone or
auxiliary input (CD player, vinyl record,
tape)
4. 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
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
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
Sound Card
Connections
• Main stereo speaker is blue
• Line out connector is green
• Microphone connector is pink
– 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
Recording Quality
• Based on the signal-to-noise ratio
– Low and mid range cards 30 to 50 decibels
– High-end range 96 to100 decibels
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
Speaker Standards
• 3D sound
– Left and right
• 3D sound on the PC
– Surround sound
designed for music and
movies that surrounds
the listener with sound
– True 3-D sound (used
in 3-D games) that
enables programmers
to make sounds
directional
• 2.1 systems
– Pair of speakers called
satellites and a
subwoofer
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)
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 Î
Windows menu in Computer Management in Windows 2000
– Digital Theatre Systems (DTS)
• Uses less compression than Dolby Digital and is a direct
competitor
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
Installing a Sound Card in a
Windows System
• 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
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, CDROM controller driver, and so on
• Most sound cards come with an easy
installation program
Device Manager
• The Device
manager displays
the several
functions of a
sound card as
separate devices.
– OPL3 is a MIDI
device
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
Configuration
Applications
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
Speakers
• Make sure they are on and getting power
• Make sure they are plugged in right
• Check the volume control settings
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 manufacturer’s web site for updates
• Check Device Manager
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.
Sound Card
Benchmarking
• PC performance issues may be related to
your sound card
• There’s a benchmark utility available
called AudioWinBench
– www.veritest.com/benchmarks/winbench/winbench
.asp
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