The document discusses sound editing and remixing. It defines sound as vibrations that can be heard and describes properties of sound waves like transmission, reflection, and absorption. It also discusses measuring sound waves through frequency, amplitude, and decibels. Finally, it covers analog and digital audio, audio compression methods like lossless and lossy, and common compressed file formats like MP3, AAC, and OGG.

1. Sound Editing and Remix
By: RP YADAV
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ISBAT University

2. What is Sound ?
• vibrations that travel through the air or another medium and can
be heard when they reach a person's or animal's ear.
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3. properties of Sound waves :
• Transmission
• Reflection
• Refraction
• Diffraction
• Absorption
• Scattering
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4. • Frequency.
Frequency is the number of occurrences of a repeating event per unit.
properties of Sound waves :
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5. • Wavelength.
• the distance over which the wave's shape repeats
properties of Sound waves :
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6. Measuring of Sound waves :
Sound energy travels in waves and is measured in frequency and amplitude.
Amplitude measures how forceful the wave is. It is measured in decibels or dB of sound pressure.
0 dB is the softest level that a person can hear.
Normal voices are around 60 dB.
Car horn are about 110 dB.
Jet sound are about 120 dB.
Firearm going off about 140 dB.
Sounds that are 85 dBA or above can permanently damage your ears. The more sound pressure a sound has,
the less time it takes to cause damage. For example, a sound at 85 dBA may take as long at 8 hours to cause
permanent damage, while a sound at 100 dBA can start damaging hair cells after only 30 minutes of listening.
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ISBATUNIVERSITY

7. Amplitude.
The amplitude of a periodic variable is a measure of its change over a single period .
properties of Sound waves :
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8. properties of Sound waves :
Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average, or
equilibrium) atmospheric pressure, caused by a sound wave.
Sound pressure
Sound pressure diagram:
1. silence;
2. audible sound;
3. atmospheric pressure;
4. sound pressure
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(Multimedia&Animation)
ISBATUNIVERSITY

9. properties of Sound waves :
The speed of sound is the distance traveled per unit time by a sound wave
speed of sound
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10. By:RPYADAV
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Analog and Digital Audio
As you can see from the diagram, the analog sound wave
replicates the original sound wave, whereas the digital sound
wave only replicates the sampled sections of the original sound
wave.
Digital audio players have become the portable audio device of
choice for many people these days. Considering the many
benefits of portable digital audio devices, the popularity is
justified. Just a few years ago, it was unheard of for someone
to carry around thousands of songs with them. Nowadays,
thanks to digital methods of audio recording and storing, entire
music collections can be carried and played back through a
single device small enough to fit in a pocket.

11. Audio Compression
•Lossless means that, digitally, regardless of the format the file is stored
in, there is no loss of data.
•The raw digital music file format types in common use are AIFF and
WAV.
•The most common compressed digital music file format types are FLAC
and ALAC.
•FLAC and ALAC compress the file, much like Zip compresses a regular
file, but more efficiently for audio information.
•FLAC has different levels of compression, trading off file size for the
amount of processing power required to compress and decompress the
file.
•On average, a lossless compressed file will be about 50-70% of its
original size.
•When de-compressed, no data has been lost.
•The bit rate for a CD-quality AIFF or WAV file is 1411 kbps (kilo-bits-per-
second).
Lossless Vs Lossy

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•Lossy means that data is removed to make the file smaller and the
sound is altered.
•The most common lossy compressed file types are MP3, AAC and OGG.
•Files are compressed by removing the data storing the least audible
sounds first.
•This often means any sounds above 16kHz (depending on compression
level) are removed, as in music, instruments only produce sounds up to
about 12-14kHz for the most part, so a person with good hearing and
good equipment might just be able to discern this, but only with effort.
•File sizes end up about 1/10th to 1/3rd the original size.
•Even after decompression, the data removed is still lost.
•The highest bit rate for lossy files is (usually) 320 kbps and the common
bit rates are 128 kbps and 192 kbps. Compare this to the lossless figure
above.
Audio Compression
Lossless Vs Lossy

13. ISBAT University
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By: RP YADAV
(Multimedia & Animation)
ISBAT UNIVERSITY
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