Sound

Chapter 15

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Types of Sound

Waveforms MIDI Sound is related to many things in

computers but only Wav and MIDI exist in PCs.

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Waveforms

Sound travels in waves High sounds are taller waves and low

sounds are shorter waves Waveforms are recorded on the computer

as 1’s and 0’s Waveforms are recorded in a number of

tracks Waveforms are commonly sampled with 8

or 16 bits 8 bit samples store 256 different

frequencies 16 bit stores 65,536 frequencies

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Waveforms

Waveforms are measured in kilohertz Usual variation of kilohertz is 11 to 44 The higher the number of KHz, the better

the quality Waveforms are very large files and some

can take over 1MBps In the beginning there were many forms

which each needed its own application Now there is WAV format for Windows

which is the most popular form of waveforms

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MIDI

Musical Instrument Digital Interface MIDI was not created for PCs Created for musicians to create, store,

and play a broad cross section of instruments

MIDI starts with a sound card with recordings of musical instruments

Number and quality of recordings tells which sound cards are more expensive

Functions much like sheet music Each instrument is called a voice

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MIDI

The number of different instruments played at once is called the polyphony

Two methods for storing musical instruments:

FM synthesis

Wavetable synthesis Wavetable is much better than FM

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Sound Cards

Device that can translate or record both MIDI and WAV formats

They take the digital sound as input and turn it into analog sound for speakers

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Sound Card Connections Average sound card can perform these

functions: Record and play waveform files Record and play MIDI files Enable recording via microphone or

auxiliary input Assist the playing of analog CD-ROMs

from the CD-ROM drive Different sound cards provide different

functions

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Speakers

Enables sound to be output to speakers Classic PCs are compatible with only two

speakers for stereo New PCs are compatible with many

speakers because of 3D sound Most speakers require a battery or AC

adapter for them to amplify sound If there is a problem it is most likely

because of the speakers and their power Powered speakers without power will

make faint sounds but must be turned off

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Microphone

Also are connected directly to the sound card

Full sized microphones must use adapters

Most problems with microphones are because of the physical microphone and not the connection or card

Be sure to check the power switch or batteries

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Line In/Line Out

Allow sound card to send and receive input and output from devices other than a microphone or speaker

Sound card can take in info from any device connected to it

Sound card can also be connected to stereo system to send its own sounds to external speakers

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CD Media

Connected in 3 different ways: ATAPI CD-ROM via 40-pin connection

Connection had nothing to do with sound; only the transfer of data from the drive

Use expansion bus itself Must use media player and open the file File is run through the bus again and sent

to the sound card Problems are caused by I/O, IRQ, or DMA

CD-ROM Connections Cards have a special CD-audio connector

that links directly to the card

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MIDI/Joystick

MIDI enabled cards have a 15-pin female DB connector

Used to plug in MIDI instruments to the card

Looks much like joystick port Sound cards now have the ability

to configure the port properly to support joysticks so that customers won’t call with complaints

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Device Drivers

Sound cards have complicated device drivers

Remember:everything as separate device Not: Sound Card Think: MIDI Card, WAV card, etc.

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Windows 9x/2000

PnP has made non-PnP cards obsolete

Most current sound cards come with the basic software needed for any playing or recording

There are a few nuances

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Device Manager

Device Manager detects anything recognizable by Windows

Occasionally there is a problem Can be changed through the

properties for that particular drive Once sound card is recognized

without errors it is ready to go

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Control Panel

Use this to test the sounds Just to make the speakers make some

noise If play button is not clickable then

something is wrong in device manager Click icon in system tray once to open

speaker volume Two clicks opens main Volume Control

Settings

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Multimedia

Rarely used Five different sections:

Audio Video MIDI CD music Advanced

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Troubleshooting Sound

All sound problems can be broken down into three different groups Physical problems Driver issues Support resources

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Physical Problems

Something isn’t turned on, plugged in, or turned up

Easiest of the three problems Check all connections and volume

settings Volume can be changed in four different

places If any are down the sound will be down

Bad wires are likely if there is a cracking sound coming through the speakers

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Drivers

Install the latest drivers Try to uninstall/reinstall Use device driver repair methods

noted earlier in the book

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Support Resources

Many little programs that Windows puts between the device drivers and the applications

Two groups: Codecs (compressor/decompressor) DirectX

If application refuses to play specific sound file check to see if you have the correct codec installed

Codec problems can be fixed by downloading the correct one

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DirectX

Windows did not get along with many popular games

Needed to run in DOS Microsoft developed DirectX to give the

programs almost direct access to the hardware

There are many versions of DirectX and each game requires one model

The box will usually state the version of DirectX to use

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Application

If a sound won’t play in an application Check control panel to test sounds If sound works here there is a

problem with the application Check the application’s sound

properties