Audio Communications: Audio Communications: SoundSound

Mr. ButlerMr. Butler

Communication SystemsCommunication Systems

John Jay High SchoolJohn Jay High School

Wappingers Central School DistrictWappingers Central School District

UPDATED 11/2011UPDATED 11/2011

Why is it important to learn Why is it important to learn about sound?about sound?

Sound is becoming increasingly important Sound is becoming increasingly important when designing for new media and when designing for new media and Internet.Internet.

You don’t have to be a musician to be a You don’t have to be a musician to be a sound designer, but familiarity with all sound designer, but familiarity with all types of audio is important.types of audio is important.

Sound FrequencySound Frequency

Sound is composed of a complex set of Sound is composed of a complex set of waves. These waves vibrate at different waves. These waves vibrate at different frequencies. frequencies. High frequencies are defined and controlled High frequencies are defined and controlled

by the TREBLE knob on your amplifierby the TREBLE knob on your amplifier Low frequencies are controlled by the BASS Low frequencies are controlled by the BASS

knobknob

Analog Audio TheoryAnalog Audio Theory

What is Analog Audio?What is Analog Audio? Analog means that the Analog means that the

sound has been sound has been recorded on an analog recorded on an analog medium, most likely medium, most likely tapetape

Analog also means Analog also means that each copy is NOT that each copy is NOT going to be equal to going to be equal to the original. the original.

Digital Audio TheoryDigital Audio Theory

Advantages of Digital Audio Advantages of Digital Audio Each copy is EQUAL to the original, and there is no Each copy is EQUAL to the original, and there is no

generation loss.generation loss. This is why the music business moved to CDs. This is why the music business moved to CDs.

Frequency RangeFrequency Range

For most professional For most professional applications, it is applications, it is desirable to record desirable to record the original sound in the original sound in as high a quality as as high a quality as possible and then possible and then sample it down.sample it down.

Frequency RangeFrequency Range

The normal range of human hearing is 20 to The normal range of human hearing is 20 to 20,000 Hertz, or cycles per second. Only very 20,000 Hertz, or cycles per second. Only very high quality sound systems and headphones are high quality sound systems and headphones are capable of reproducing this range.capable of reproducing this range.

Small computer speakers are capable of Small computer speakers are capable of reproducing a more limited range of frequencies.reproducing a more limited range of frequencies.

Dynamic RangeDynamic Range

Dynamic range is the degree to which the Dynamic range is the degree to which the sound gets louder and softer. sound gets louder and softer.

The wider the dynamic range, the more natural The wider the dynamic range, the more natural a sound appears and he greater the emotional a sound appears and he greater the emotional impact.impact.

Most recording systems seek to have the Most recording systems seek to have the widest dynamic range possible.widest dynamic range possible.

FormatsFormats

Sound use to come in Sound use to come in only two media, tape only two media, tape and vinyl. Now, and vinyl. Now, myriad formats are myriad formats are available, including available, including CD and Minidisk.CD and Minidisk.

Some common Some common computer formats computer formats include MP3, AIFF, include MP3, AIFF, WAV. WAV.

MIDIMIDI

MIDI: MIDI: MMusical usical IInstrument nstrument DDigital igital IInterfacenterface MIDI was developed in the mid-1980sMIDI was developed in the mid-1980s Allows keyboard synthesizers talk to the Allows keyboard synthesizers talk to the

computer. computer. RingtonesRingtones

Audio on the InternetAudio on the Internet

MP3 is a technology MP3 is a technology that created its own that created its own industry.industry.

Fueled mainly by Fueled mainly by college students, MP3 college students, MP3 was a quick way to was a quick way to exchange and share exchange and share music over the music over the Internet. Internet.

Audio Internet FormatsAudio Internet Formats

There are many There are many different formats for different formats for audio on the Internet, audio on the Internet, but five of them are but five of them are the most common.the most common. MP3MP3 RealAudioRealAudio Windows Media PlayerWindows Media Player QuickTimeQuickTime AIFF and WAVAIFF and WAV

MP3MP3

the file extension for MPEG Audio the file extension for MPEG Audio Layer-3, Layer-3, a set of standards for standards for compressing and downloading compressing and downloading audio files from the Internet.audio files from the Internet.

Most popular formatMost popular format Widely used for exchange music Widely used for exchange music

filesfiles Good compression schemeGood compression scheme Typical size per song: 3 to 4 MB.Typical size per song: 3 to 4 MB. Although the legal issues are still Although the legal issues are still

being worked out, MP3 is here to being worked out, MP3 is here to stay.stay.

QuickTimeQuickTime

Apple Computer ProductApple Computer Product QuickTime recently QuickTime recently

converted to a streaming converted to a streaming formatformat

Before QuickTime, you Before QuickTime, you had to download had to download QuickTime files.QuickTime files.

AIFF and WAVAIFF and WAV

AIFF stand for Audio Interchange File AIFF stand for Audio Interchange File Format Format

WAV files are called “wave” files. Both are WAV files are called “wave” files. Both are high-quality audio files, and both require a high-quality audio files, and both require a lot of memory. lot of memory.

If you want CD-quality sound, AIFF or Wav If you want CD-quality sound, AIFF or Wav will deliver it. will deliver it.

ReferencesReferences

Digital Creativity, “Techniques for Digital Digital Creativity, “Techniques for Digital Media and the Internet”-Bruce WandsMedia and the Internet”-Bruce Wands