1. Chapter 14 Recording and Editing Sound

2. Getting Started FAQs: − How does audio capability enhance my PC? − How does your PC record, store, and play digital audio? − What do I need to know about converting music files? − What should I know about MIDI? − How do computers recognize and generate speech? 2Practical PC 6th Edition Chapter 14

3. How does audio capability enhance by PC Sound adds a new dimension to your computing experience – Beeps and sound effects provide feedback as you use your PC – Music lovers can listen to sample tracks – Children can listen to stories – Visually impaired individuals can have the screen contents read to them Computers work with two general categories of sound – Digital audio is a recording of real sound converted into electronic signals – Synthesized sound has not been recorded from a live source, but instead has been generated by a machine Each sound category has unique characteristics and applications 3Practical PC 6th Edition Chapter 14

4. How does audio capability enhance by PC 4Practical PC 6th Edition Chapter 14

5. How does my PC record, store, and play digital audio? To digitally capture sound, you need a microphone and sound software A sound wave provides information about a sound – Height of wave indicates volume, called amplitude – Time between wave peaks indicates the sound’s frequency To digitally store a sound wave, your PC periodically records a sample of the wave’s amplitude as a binary number – Sampling rates are measured in kHz (kilohertz), where 1 kHz is 1,000 samples per second – For human speech, 11 kHz works fairly well. For music, 22 kHz to 44 kHz is required – Digital sound files that have not been compressed are big – Wave is a popular uncompressed audio file format 5Practical PC 6th Edition Chapter 14

6. How does my PC record, store, and play digital audio? 6Practical PC 6th Edition Chapter 14

7. What do I need to know about converting music files? Ripping is slang for importing tracks from a CD or DVD to your computer’s hard disk – Technical term for ripping is digital audio extraction – Ripping is handy when moving files between PCs and devices Music file formats – CD-DA (Compact Disc Digital Audio) format for music on CDs – Music from CDs is usually compressed into: MP3, AAC (Advanced Audio Coding), and WMA (Windows Media Audio) Many software tools for ripping CD tracks are available In the U.S., ripping music for personal use is controversial 7Practical PC 6th Edition Chapter 14

8. What do I need to know about converting music files? 8Practical PC 6th Edition Chapter 14

9. What should I know about MIDI? MIDI (musical instrumental digital interface) specifies a standard way to store music data – MIDI files contain instructions, called MIDI messages, for synthesizing music based on pitch, volume, and duration of each note made by each instrument – MIDI is suitable for instrumental music, but not for vocals – MIDI’s advantage lies in its ability to store lengthy musical sequences in a small file Use sequencer software to capture the musical themes from a MIDI instrument or enter the notes on a musical staff Edit your composition by assigning notes to instruments, adding harmony, and inserting a percussion track 9Practical PC 6th Edition Chapter 14

10. What should I know about MIDI? 10Practical PC 6th Edition Chapter 14

11. How do computers recognize and generate speech? Computers produce sound that resembles the spoken word through speech synthesis – Most speech synthesizers string together basic sound units called phonemes Speech synthesis system typically includes text-to-speech software and synthesizing hardware – Text-to-speech software examines the text on a PC and breaks it down into a series of sounds that can produce output – Synthesizing software consists of electronic circuitry that can generate speech or musical sounds Unlike digitized speech, synthesized speech can theoretically produce any words or phrases 11Practical PC 6th Edition Chapter 14

12. How do computers recognize and generate speech? 12Practical PC 6th Edition Chapter 14

13. Hardware: Audio devices Your computer’s sound card is responsible for transforming the bits stored in an audio file into sound – Expansion cards – Integrated audio Basic audio circuitry is sufficient for most home and small business use A digital signal processor transforms digital bits into analog waves and vice versa, and handles compression and decompression 13Practical PC 6th Edition Chapter 14

14. Hardware: Audio devices 14Practical PC 6th Edition Chapter 14

15. Hardware: Audio devices Your PC outputs sound to speakers or headphones The bundled microphone might be suitable for radio-quality voice recording and sound effects – Shop for a better-quality microphone for multimedia or professional audio projects External speakers should be used for adequate volume – 2.1 system – 5.1 system Some speakers draw power from the computer 15Practical PC 6th Edition Chapter 14

16. Hardware: Audio devices 16Practical PC 6th Edition Chapter 14

17. Hardware: Audio devices Portable audio player – Pocket-sized, battery-powered device that stores digital music – Transfer music from your PC or buy songs online – Connect to earbuds, headphones, or car or home stereo system – Supports a variety of compressed audio formats – Some can also play videos and e-books Rhythm and music activities are becoming increasingly popular 17Practical PC 6th Edition Chapter 14

18. Hardware: Audio devices 18Practical PC 6th Edition Chapter 14

19. Can I copy it? What do you think? – When you purchase a music CD, do you believe that you have the right to convert it into any format (such as WMA or MP3) for your own use? – Do you think the Digital Millennium Copyright Act should be revised to allow people to circumvent DRM for music that has been purchased legitimately? – Have you ever been prevented from copying music by some type of DRM technology? 19Practical PC 6th Edition Chapter 14