1. Sound Importance of sound How to make sound (types)
How to record and edit sound on your computer
How to incorporate sound in your MM work

2. Intro to Sound
We rely on SOUND to enhance Multimedia Applications
WHY?
Easily capture the attention of users
Facilitate easy learning
Set the mood

3. On the Web, sound offers
Background music, narration, and sound effects
Create moods
Recorded testimonials from customers are used to market and sell products and services. Interviews with stars and listening to a sample of their achievements
One-way audio offers on-demand radio listening around the world. These radio programs broadcast music, talk shows, and live interviews.
Internet Audio Conferencing or Internet telephony that allows two-way, full-duplex audio conversations over the Web. With Internet telephony you can talk to friends or family without the cost of a long-distance phone call.

4. What is Sound? Play audio clip Bells Oh
Sounds are pressure waves of air
Visualize the sounds as a series of recurring waves called a waveform.
Volume - the higher the wave the higher the sound
Pitch or frequency number of cycles per second (cps), or Hertz
Play audio clip
Bells Oh

5. Sources of Sound Pre-packaged
Some sound files may come with your computer's operating system or with programs that are installed on your computer.
Purchased or Borrowed
Download from stock companies – $$$ or provided free
Create Your Own Sound Clips
Recording program with a computer's operating system (such as Sound Recorder) and speak into a microphone attached to the computer – quality will not be the best
Recording studio with equipment such as DAT (Digital Audio Tape) devices that record sounds digitally. Produces a high quality commercial product
Electronic instruments such as synthesizers can be used to create music sound files. Connecting the instrument to a computer allows the sounds to be captured in a MIDI (Musical Instrument Digital Interface) format.

6. (electrical signal) analog
How is Sound Recorded?
(electrical signal) analog
Microphone translates movement into electrical signals (analog). Then tape recorder translates the waveform from an electrical signal on a wire, to a magnetic signal on a tape (analog)
Analog-to-Digital Converter (ADC). The ADC captures a snapshot of the electric voltage on an audio line and represents it as a digital number that can be sent to a computer.

7. Digital audio
It is the actual representation of sound stored in the form of digital numbers (Samples)
It represents the loudness of the sound at a slice of time
It sounds the same every time played.

8. How is Sound Recorded and Played?

9. What is Digital Format?
In a multimedia application sound must be in a digital form (string of 1s and 0s).
A sound can be recorded directly in digital form or an analog sound can be converted to a digital sound.
To convert analog sounds to digital sounds a technique is used called digital sampling

10. Digital audio sampling I
Sampling: is converting the sound wave to numbers using the magnitude of the wave. That is from analog to digital. How?
Divide the horizontal axis (the time dimension) into discrete uniform pieces.
Sample rate (frequency): is how often the samples are taken (fraction of a second)

11. Digital audio sampling II
Sample size: the amount of information stored about each sample 8 or 16 bits . Also known as bit depth.
Quantization – divide the vertical axis (signal strength) into pieces. Sometimes, a non-linear function is applied.
– 8 bit quantization divides the vertical axis into 256 levels. 16 bit gives you levels.

12. Nyquist’s Sampling Theorem
How many Samples to take?
KHz — Speech (Telephone 8KHz)
22.05 KHz — Low Grade Audio (WWW Audio, AM Radio)
44.1 KHz — CD Quality
For lossless digitization, the sampling rate should be at least twice the maximum frequency responses.
Indeed many times more the better.

13. Memory Required for 1 Minute of Digital Audio

14. Reasons to use digital audio
It is consistent: the digital media will sound as good at the end as it did in the beginning when it was created.
A wider selection of application software and system support for digital audio is available.
The preparation and programming required for creating digital audio do not demand knowledge of music theory;
working with MIDI data usually does require familiarity with musical scores, keyboards, and notation as well as audio production.

15. Preparing digital audio files
Two important aspects have to be taken in considerations while preparing sounds:
Balancing the sound quality with the available hardware resources.
Remember the relation between sampling frequency and sound quality?
Setting proper recording levels to get clean recording. If Recording level too high, it will introduce noise. Conversely if it is too low it is useless.

16. QUALITY OF DIGITAL RECORDING
Depends ON
Sample Rate
Sample Size (level)
Channels
Codecs

17. QUALITY OF DIGITAL RECORDING Channels
Mono signal
one stream of data reproduced equally on both speaker channels
Lose stereo separation
Stereo signal
consists of two streams of data working together (left,right)
double the size of mono file

18. QUALITY OF DIGITAL RECORDING

19. QUALITY OF DIGITAL RECORDING CODECS
Software programs that greatly compress the audio file size
Codecs use lossy compression by
removing redundant and less-significant data

20. How big can audio get?
An example of uncompressed sound with CD quality for 1 minute of audio:
1 minute of recording  60 seconds
60 * 44,100 samples/second  2,646,000 samples
2,646,000 samples * 16bits per sample  42,336,000 bits
42,336,000 bits * 2 (stereo, 2 channels)  84,672,000 bits
84,672,000 bits / (8bits per byte)  10,884,100  About 10 MB (Megabytes)!!!

21. Musical Instrument Digital Interface MIDI sounds
Allows sounds synthesizers from different manufacturers to communicate with each other by sending messages along cables connected to devices.
MIDI is a standard for encoding music, not sound. That is a shorthand representation of music stored in numeric form
Contains instructions for creating the frequency, volume and duration of notes that sound like various musical instruments
MIDI files are recording of musical actions for example:
Pressing a piano key.

22. Midi versus digital audio
MIDI files are much more compact than digital audio files. The size of a MIDI file is completely independent of playback quality.
In general, MIDI files will be 200 to 1,000 times smaller than CD-quality digital audio files. For example:
MIDI
21KB, 2min 36s
Digital Audio
612KB, 56s
Because MIDI files are small, they don’t take up as much RAM, disk space, and CPU resources.
Which one is a live recording and which one is computer generated? Can you tell the difference?
One
Two

23. Where to use Midi don’t need spoken dialog.
Because they are small, MIDI files embedded in Web pages. When loaded, MIDI files play more quickly than their digital equivalents.
Midi files are editable, thus it can be used in the application where it might be needed to change the length of the file without changing the quality of the audio quality.
Digital audio wont work because you don’t have enough RAM, hard disk space, CPU processing power, or bandwidth.
don’t need spoken dialog.

24. Disadvantages of using MIDI files
You can’t be certain that playback will be accurate if the MIDI playback device is not identical to the device used for production.
Does not produce high-quality vocals غناء
Even with the General MIDI standard the sound of a MIDI instruments varies according to the electronics of the playback device and the sound generation method it uses.
Also, MIDI cannot easily be used to play back spoken dialog.

25. Components of a MIDI System
Synthesizer:
It is a sound generator (various pitch, loudness, tone colour).
A good (musician’s) synthesizer often has a microprocessor, keyboard, control panels, memory, etc.
Sequencer:
It can be a stand-alone unit or a software program for a personal computer. (It used to be a storage server for MIDI data. Nowadays it is more a software music editor on the computer.
It has one or more MIDI INs and MIDI OUTs.
Track:
Track in sequencer is used to organize the recordings.
Tracks can be turned on or off on recording or playing back.

26. Components of a MIDI System
Channel:
MIDI channels are used to separate information in a MIDI system.
There are 16 MIDI channels in one cable.
Channel numbers are coded into each MIDI message.
Timbre:
The quality of the sound, e.g., flute sound, cello sound, etc.
Multitimbral – capable of playing many different sounds at the same time (e.g., piano, brass, drums, etc.)
Pitch:
musical note that the instrument plays
Voice:
Voice is the portion of the synthesizer that produces sound.
Synthesizers can have many (12, 20, 24, 36, etc.) voices.
Each voice works independently and simultaneously to produce sounds of different timbre and pitch.
Patch: the control settings that define a particular timbre.

27. Making MIDI audio To make MIDI audio you need:
Sequencing software
Sound synthesizer
A MIDI keyboard
Instruments that can be synthesized are identified by general MIDI numbering system that ranges from 0 to 127
Good sequencing software allow printing and scanning the music sheets.

28. Adding sound to MM project
Steps to bring audio recording into MM project
Decide what kind of sound in needed (such as background music, special sound effects, and spoken dialog).
Decide where these audio events will occur in the flow of your project.
Fit the sound cues into your story board, or make up a cue sheet.
Decide where and when you want to use either digital audio or MIDI data.

29. Other steps
Acquire source material by creating it from scratch or purchasing it.
Edit the sounds to fit your project.
Test the sounds to be sure they are timed properly with the project’s images. This may involve repeating previous steps until everything in sync.

30. Editing digital recording
Once recording and digitizing been made, editing will be made. Following are list of editing operations that are most used:
Trimming: removing blank space from the beginning and extra time at the end.
Splicing and assembly: putting short segments to gather in a longer one.

31. Other editing operations
Volume adjustment: when assembling different segments in one, the volume may be not the same, thus it is important to be able to adjust the sound volume.
Format conversion: one should be able to convert audio files from one type of files to types that director plays. It plays AIFF, SWA, AU, or WAV audio files.

32. Other editing operations
Resambling or downsampling: If you have recorded your sound at 16-bit sample size but are using lower rates in your project, then you must edit the file downsasmpling its contents.
Fade-ins and fade-outs: beginning and ending the sound gradually and in a smooth way.

33. More editing operations
Equalization: allow modifying recorded content to sound brighter or darker.
Time stretching: some programs allow alter the length of the sound file without changing the pitch(النغمة)
Digital signal processing: add special sound effects
Reversing sound

34. Sound-Editing Software - cont
Audacity Software
Edit the clip, Combine it with other sound files Add transitions or special effects

35. Sound-Editing Software - cont
Recording sound using WaveStudio
Edit the clip, Combine it with other sound files Add transitions or special effects

36. Adding sounds

37. Uses for adding sounds We can mix sounds We can create echoes
We even know how to change the volumes of the two sounds, even over time (e.g., fading in or fading out)
We can create echoes
We can add sine (or other) waves together to create kinds of instruments/sounds that never existed in nature, but sound complex

38. Sound File Formats

39. Sound File Formats - continued
So which format is best?
uncompressed