Easy-to-follow video tutorials help you learn software, creative, and business skills.Become a member

What is sound?

From: Digital Audio Principles

Video: What is sound?

So what is sound? Sound is essentially vibrations that travel through the air, it's the molecules around us moving. What happens is you have something that creates a disturbance in air pressure. And that disturbance creates these different patterns of vibrations in the air pressure, and these patterns of vibrations of shifting molecules are what we perceive as different sounds. And they travel from the initial sound source or where the disturbance first occurs and travel out as sound waves. You can think of sound as kind of having three stages in life.

What is sound?

So what is sound? Sound is essentially vibrations that travel through the air, it's the molecules around us moving. What happens is you have something that creates a disturbance in air pressure. And that disturbance creates these different patterns of vibrations in the air pressure, and these patterns of vibrations of shifting molecules are what we perceive as different sounds. And they travel from the initial sound source or where the disturbance first occurs and travel out as sound waves. You can think of sound as kind of having three stages in life.

There is the production stage, where it's actually created for the first time, and that's where there are some sort of impact, or action, that creates a vibration, or movement. You can think of this as hitting a snare drum head, or a cowbell, or plucking a guitar string. This creates a vibration, and it starts to move the air pressure around it. The second stage is the propagation, or the point where, kind of, sound actually travels to us. And so the disturbance in the air pressure actually travels via sound waves. So these sound waves are traveling out and they run into things.

Sometimes, they hit things like walls and then bounce and are redirected, and other times, they actually hit things that are sensitive to the vibrations, like our ears or microphones. And this brings us to the third stage, which is when the sound waves actually reach something that's sensitive to these changes in air pressure, better known as a receiver. And that receiver can take those changes in air pressure and convert them into something else. As humans, we pick up these changes in air pressure, and we actually perceive them as sound. A classic analogy for sound waves and kind of thinking about how sound travels is to think about throwing a rock into a still pond, and thinking about how the little ripples go out in all directions and eventually hit the shore, hit different things.

You think about that rock being kind of the production stage, and then the propagation stage being those waves or ripples as they go out from that center, and this bring us to the third stage, the perception stage. The perception stage is what those waves actually hit. In the case of hearing, it would be hitting our ears, or in the case of recording, it would be hitting a microphone. So each of these disturbances is different and will generate kind of a unique pattern of variations in the air pressure, and this is what gives the sound its character, this is kind of how we know a snare drum from a human voice.

They have different patterns. So there are two characteristics of waveforms that affect how we hear a sound. There is amplitude, or the loudness, and frequency. Let's take a look at amplitude. This is the relative strength of a sound or how much of a change in air pressure occurs. So in our visual we can see some waveforms with less amplitude and some waveforms with more amplitude, and we perceive these differences in amplitude as essentially quieter and louder sounds. Loudness is the term that we use to describe how humans perceive amplitude.

Another important unit of measurement we are talking about loudness is the decibel, and it's got two different applications, there is the decibel SPL or Sound Pressure Level, which is what we use to measure the strength of the sound. We have got a little list here of some of the different SPL levels, and you can see kind of how they correspond with different things, with zero dB representing the threshold of human hearing, or how loud something has to be in order for us to be able to hear it at all. 20 dB is whispering, 60 dB conversation, et cetera. A 130 dB the threshold of pain.

If you are at a concert, and you have to leave because it hurts too much, it's probably around 130 dB. And then if you get up to 194 dB, which is really, really loud, we are talking about shock waves, and I guess kind of above that you are thinking about stuff like the sonic boom and stuff that you don't want to be too close to when you hear, because it's pretty loud. It's important to note that decibels are logarithmic, and this means that the volume changes represented by decibels aren't weighted on a one-to-one basis. To that point, every time a sound goes up by three decibels, it effectively is becoming twice as loud.

We have got a little list here of some of the different SPL levels, and you can see how they correspond to different things. We also use the decibel to measure the loudness of sound and in terms of audio, it kind of refers to the signal level or the volume, and you will that when we are working with digital audio, we will talk about turning a sound up a few dB or down a few dB. In the next movie, we will take a look at hertz and frequency response.

Show transcript

This video is part of

Image for Digital Audio Principles
Digital Audio Principles

110 video lessons · 27131 viewers

Dave Schroeder
Author

 
Expand all | Collapse all
  1. 50s
    1. Welcome
      50s
  2. 39m 10s
    1. What is sound?
      4m 15s
    2. Hertz and frequency response
      5m 34s
    3. Phase
      2m 39s
    4. Capturing audio
      3m 39s
    5. Sample rate
      6m 16s
    6. Bit depth
      9m 47s
    7. The waveform
      5m 3s
    8. Audio file formats
      1m 57s
  3. 7m 25s
    1. What is a digital audio workstation?
      2m 59s
    2. Typical DAW signal flow
      4m 26s
  4. 50m 33s
    1. What microphones do
      1m 57s
    2. Element types
      5m 0s
    3. Pickup patterns
      6m 51s
    4. Axis
      2m 52s
    5. Frequency response and the proximity effect
      5m 10s
    6. Phase issues
      1m 41s
    7. Microphone types
      8m 44s
    8. Miking vocals
      5m 39s
    9. Miking amplifiers
      2m 17s
    10. Miking drums
      10m 22s
  5. 16m 39s
    1. Cables and connectors overview
      2m 42s
    2. Balanced and unbalanced cables
      3m 19s
    3. Common cable types
      7m 13s
    4. Cable tips
      3m 25s
  6. 12m 16s
    1. What is an I/O device?
      1m 41s
    2. Analog to digital conversion
      3m 10s
    3. Tour of an audio interface
      4m 49s
    4. Interface considerations
      2m 36s
  7. 21m 5s
    1. What is a preamp?
      3m 21s
    2. Input levels
      5m 29s
    3. Padding
      2m 18s
    4. Phantom power
      2m 37s
    5. Phase reverse
      3m 4s
    6. Preamp demo
      4m 16s
  8. 12m 56s
    1. What is a mixer?
      5m 55s
    2. Input section
      1m 17s
    3. Channel strips
      3m 16s
    4. Master section
      2m 28s
  9. 18m 21s
    1. What is monitoring?
      2m 11s
    2. Speakers
      4m 47s
    3. Room considerations
      5m 43s
    4. Headphone types
      3m 50s
    5. Monitoring levels
      1m 50s
  10. 15m 23s
    1. What role do computers play?
      1m 36s
    2. Performance issues
      4m 11s
    3. Hard drives
      4m 38s
    4. Mechanical noise
      2m 10s
    5. Authorization
      2m 48s
  11. 6m 54s
    1. Planning for recording
      54s
    2. Doing a system check
      1m 26s
    3. Planning your inputs
      1m 42s
    4. The recording environment
      2m 52s
  12. 25m 52s
    1. Types of digital audio software
      38s
    2. Multi-track recorders/sequencers
      4m 56s
    3. Two-track recorders/waveform editors
      4m 55s
    4. Loop-based music production software
      5m 44s
    5. Plug-ins
      6m 56s
    6. Other varieties
      2m 43s
  13. 18m 59s
    1. Common components
      46s
    2. The transport
      2m 4s
    3. The toolbar
      3m 19s
    4. The Edit/Arrange window
      4m 42s
    5. The mixer
      5m 8s
    6. The file list
      3m 0s
  14. 19m 17s
    1. Setting up a session
      3m 30s
    2. Assigning inputs and getting signals
      3m 19s
    3. Input modes
      3m 28s
    4. Overdubbing and punching
      5m 14s
    5. Bouncing down
      3m 46s
  15. 19m 42s
    1. What is editing?
      1m 21s
    2. Waveforms
      2m 53s
    3. Making silent cuts and trims
      7m 1s
    4. Fades and automation
      8m 27s
  16. 1h 23m
    1. What are plug-ins?
      3m 0s
    2. Using plug-ins
      6m 11s
    3. EQs
      7m 4s
    4. Dynamics pt. 1: Compressors, limiters, expanders, and gates
      5m 40s
    5. Dynamics pt 2: Applying dynamic effects
      7m 2s
    6. Pitch shifting
      6m 14s
    7. Reverb
      9m 28s
    8. Echo and delay
      6m 23s
    9. Modulation effects: Phaser, flanger, and chorus
      9m 39s
    10. Sound tools pt. 1: About, gain, normalize
      7m 39s
    11. Sound tools pt. 2: Reverse and time compression/expansion
      6m 29s
    12. Sound tools pt. 3: Noise reducers, dither
      8m 11s
  17. 23m 43s
    1. What is MIDI?
      3m 6s
    2. Keyboard controllers
      1m 23s
    3. Computer-based virtual instruments
      1m 6s
    4. Control surfaces
      1m 6s
    5. Recording and editing MIDI
      12m 4s
    6. Virtual instruments
      4m 58s
  18. 27m 29s
    1. What is mixing?
      1m 54s
    2. Some common objectives
      3m 4s
    3. Some useful techniques
      5m 59s
    4. A quick mixing demo
      16m 32s
  19. 18m 48s
    1. What is mastering?
      2m 24s
    2. Sonic maximization
      9m 43s
    3. Final preparations and exporting
      6m 41s
  20. 13m 34s
    1. What is audio compression?
      2m 16s
    2. Popular formats
      2m 9s
    3. Bit rate, sample rate, and channels
      5m 42s
    4. Other adjustments and considerations
      3m 27s
  21. 15m 6s
    1. Essential gear
      7m 36s
    2. Voice recording setups
      1m 43s
    3. The voice production process
      5m 47s
  22. 10m 4s
    1. Analog vs. digital
      2m 48s
    2. Tube vs. solid state
      5m 6s
    3. The continual upgrade
      2m 10s
  23. 18s
    1. Goodbye
      18s

Start learning today

Get unlimited access to all courses for just $25/month.

Become a member
Sometimes @lynda teaches me how to use a program and sometimes Lynda.com changes my life forever. @JosefShutter
@lynda lynda.com is an absolute life saver when it comes to learning todays software. Definitely recommend it! #higherlearning @Michael_Caraway
@lynda The best thing online! Your database of courses is great! To the mark and very helpful. Thanks! @ru22more
Got to create something yesterday I never thought I could do. #thanks @lynda @Ngventurella
I really do love @lynda as a learning platform. Never stop learning and developing, it’s probably our greatest gift as a species! @soundslikedavid
@lynda just subscribed to lynda.com all I can say its brilliant join now trust me @ButchSamurai
@lynda is an awesome resource. The membership is priceless if you take advantage of it. @diabetic_techie
One of the best decision I made this year. Buy a 1yr subscription to @lynda @cybercaptive
guys lynda.com (@lynda) is the best. So far I’ve learned Java, principles of OO programming, and now learning about MS project @lucasmitchell
Signed back up to @lynda dot com. I’ve missed it!! Proper geeking out right now! #timetolearn #geek @JayGodbold
Share a link to this course

What are exercise files?

Exercise files are the same files the author uses in the course. Save time by downloading the author's files instead of setting up your own files, and learn by following along with the instructor.

Can I take this course without the exercise files?

Yes! If you decide you would like the exercise files later, you can upgrade to a premium account any time.

Become a member Download sample files See plans and pricing

Please wait... please wait ...
Upgrade to get access to exercise files.

Exercise files video

How to use exercise files.

Learn by watching, listening, and doing, Exercise files are the same files the author uses in the course, so you can download them and follow along Premium memberships include access to all exercise files in the library.


Exercise files

Exercise files video

How to use exercise files.

For additional information on downloading and using exercise files, watch our instructional video or read the instructions in the FAQ.

This course includes free exercise files, so you can practice while you watch the course. To access all the exercise files in our library, become a Premium Member.

Are you sure you want to mark all the videos in this course as unwatched?

This will not affect your course history, your reports, or your certificates of completion for this course.


Mark all as unwatched Cancel

Congratulations

You have completed Digital Audio Principles.

Return to your organization's learning portal to continue training, or close this page.


OK
Become a member to add this course to a playlist

Join today and get unlimited access to the entire library of video courses—and create as many playlists as you like.

Get started

Already a member?

Become a member to like this course.

Join today and get unlimited access to the entire library of video courses.

Get started

Already a member?

Exercise files

Learn by watching, listening, and doing! Exercise files are the same files the author uses in the course, so you can download them and follow along. Exercise files are available with all Premium memberships. Learn more

Get started

Already a Premium member?

Exercise files video

How to use exercise files.

Ask a question

Thanks for contacting us.
You’ll hear from our Customer Service team within 24 hours.

Please enter the text shown below:

The classic layout automatically defaults to the latest Flash Player.

To choose a different player, hold the cursor over your name at the top right of any lynda.com page and choose Site preferencesfrom the dropdown menu.

Continue to classic layout Stay on new layout
Exercise files

Access exercise files from a button right under the course name.

Mark videos as unwatched

Remove icons showing you already watched videos if you want to start over.

Control your viewing experience

Make the video wide, narrow, full-screen, or pop the player out of the page into its own window.

Interactive transcripts

Click on text in the transcript to jump to that spot in the video. As the video plays, the relevant spot in the transcript will be highlighted.

Are you sure you want to delete this note?

No

Your file was successfully uploaded.

Thanks for signing up.

We’ll send you a confirmation email shortly.


Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

Keep up with news, tips, and latest courses with emails from lynda.com.

Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

   
submit Lightbox submit clicked
Terms and conditions of use

We've updated our terms and conditions (now called terms of service).Go
Review and accept our updated terms of service.