Copyright © 2007 Heathkit Company, Inc. All Rights Reserved PC Fundamentals Presentation 26 – The Computer Sound System

2 Objectives At the end of this presentation, you will be able to:

3 Identify the various inputs and outputs included on common PC sound systems. Explain why sampling rate and bit resolution and is important in a digital sound system. Explain the differences in stereo, 4-channel, 5.1, and 7.1 audio. Describe the three levels defined by Dolby that are helpful in understanding the capabilities of a computer’s sound system.

4 Early computers had a single, small speaker built inside Today’s computers have stereo speakers and a microphone input. Microphone Stereo Speakers Built-in 2 inch speaker

5 Multimedia Components CD-ROM Drive Sound Card Microphone Speakers Camera High-Performance Video Card DVD-ROM Drive

6 What Audio Enables Foreign Language Training Music Composition Background Music as You Work Telephone through Your Computer Voice Recognition Sound Effects for Presentations and Games

7 How Computer Audio Works (Today’s Science Lesson)

8 One cycle One Second Hertz Amplitude

9 High Amplitude Low Amplitude

Hertz The Amplitude is called VOLUME The Frequency is called PITCH

11 A Speech Sonogram (What Your Voice Looks Like)

12 Sound Synthesis and Sampling Techniques

13 Sampling

14 Samples Stored as Digital Values

15 Waveform Reconstructed From Samples

16 Reconstructed Versus Original

17 Half the Sampling Rate

18 The Reconstructed Waveform Original Reconstructed

19 Sampling Rate = Twice the Pitch Minimum Sampling Rate 40 Hz 800 Hz 2,000 Hz 20,000 Hz 40,000 Hz 100,000 Hz Pitch Pitch 20 Hz 20 Hz 400 Hz 400 Hz 1,000 Hz 1,000 Hz 10,000 Hz 20,000 Hz 50,000 Hz

20 Storing a Four Minute Song 4 minutes x 60 seconds/min = 240 seconds 240 sec X 40,000 samples/sec = 9,600,000 samples At one byte per sample, it will take 9.6 megabytes to store a 4 minute song.

21 Improving the Sound Quality Standard—44.1 kHz sampling, 16-bits per sample, Stereo (2 channels) Surround Sound—48 kHz sampling, 20-bits per sample, 5.1 channels High Definition—192 kHz sampling, 32-bits per sample, 7.1 channels

22

23 Dolby’s Three Levels of HD Audio for PCs. Dolby Sound Room—2 Channel Audio that can simulate 5.1 audio. Dolby Home Theater —6-channel (5.1) audio Dolby Master Studio —8-channel (7.1) audio.

24 The Sound Card

Sound Card PCI Bus Connector

Sound Card

27 Software Sound BLASTER Sound Blaster ® PCI128 Software Also on this CD: Creative Inspire TM Microsoft® Internet Explorer with Microsoft NetMeeting TM CREATIVE CLI Part No.: XXXXXXXXX ©1998 Creative Technology Ltd. All rights reserved. Sound Blaster, the Sound Blaster logo, and the Creative logo are registered trademarks and Inspire is a trademark of Creative Technology Ltd. In the United States and/or other countries.

28 Stereo Speakers with Built-in Amplifiers. SOUND FORCE 505 VOLUME SOUND FORCE 505 POWER

29 Four Speaker System VOLUME

Surround Sound Left Front Left Rear Right Front Right Rear Center Sub-Woofer

Surround Sound

Copyright © 2007 Heathkit Company, Inc. All Rights Reserved PC Fundamentals End