Hello, my name is Mr. Hogan.

I'm excited to be learning with you today.

We are going to have such a great time learning about data representation of images and sounds.

I will be supporting you with our learning during these lessons.

I'm so pleased that you've decided to learn about editing sound.

We are going to do brilliantly.

Welcome to today's lesson from the unit Data Representation: Images and Sound.

This lesson is called Editing Sound.

During this lesson, you'll be using sound editing software to edit and manipulate digital sound files.

It's going to be really exciting.

I'm really looking forward to it.

So we have four keywords for today's lesson.

We'll be learning these throughout the lesson.

So the first one is waveform.

This is a visual representation of a sound file, showing how the amplitude of a sound varies over time.

Our next keyword is channel.

This is an individual stream of audio in a sound file.

The third one is mono.

This produces the same sound in both the left and right speakers or headphones.

Our last keyword we're gonna be using is stereo.

This presents sounds separately for the left and right speakers or headphones.

So we're gonna be using these words throughout the lesson, so if you don't understand what they mean at the moment, don't worry.

You soon will.

So the lesson outlined today is split into two.

The first one is describe the trade off between size and quality.

And the second one is edit and manipulate sound files.

This is gonna be a great lesson, a real good lesson to get practical with editing sound.

Let's move on to the first part of the lesson, describe the trade off between size and quality.

Sam is asking, "Why do we even need to learn about the size and quality of sound files? It seems kind of pointless." Sofia's replying, "Think about how often we use sound in our lives, music, games, even videos.

Understanding how the size and quality of sound files affect what we hear can explain why some audio sounds fantastic while others don't." So that's a real good explanation of why it's really important we learn about the size and quality of sound files.

Sam replies, "Okay, but how does that help me personally? I'm not planning to make music or anything." He's got a good point.

Sofia replies, "It's not just about making music.

When you're streaming a game or editing a video, you want it to sound good, right? Learning this helps you choose the right setting to balance quality and file size." So she's right.

It's not just about making music, but when you're streaming a game or editing a video, you may have some options about the quality of the sound you hear and making sure it's got the correct balance for you.

Let's have a check.

Why is it useful to understand the balance between size and quality of sound files? Is it a, it helps you make better choices when streaming or editing audio and video, b, it helps you understand why some sounds are louder than others, or is it c, it helps you learn to play a musical instrument? Take your time, think about your answer, and you can always rewind the video just to see what was said before.

Let's look at the answer.

It is a, it helps you make better choices when streaming or editing audio and video.

Well done if you got that right.

The number of samples taken per second is called the sample rate.

Typical value is 44 100 samples per second.

For each sample, a sequence of bits is recorded.

The number of bits recorded per sample is called the sample resolution, or sometimes known as bit depth.

A typical value is 16 bits per sample.

So you can see in the diagram there that there are 16 bits that has been sampled at that point in the sound wave.

Sam is asking, "Hey, Sofia, this song that we're streaming using your phone sounds great." Sofia's replied, "Yes, but listening to songs uses so much of my data allowance each week." Sofia's right.

High quality sounds with a high sample resolution, or bit depth, and high sample rate take up more data, require more processing power, and take longer to transmit.

Sam's asking, "I can change the quality of the songs I stream from my music service so it doesn't use as much data." Sofia's reply, "Oh yes, when I'm not on Wi-Fi, I can switch to the lowest quality to save my data." That's right, low quality sounds, with a low sample resolution, or bit depth, and a low sample rate, take up less data, require less processing power, and take less time to transmit.

Sample rate refers to how often sound is captured each second, usually measured in Hertz, or sometimes referred to as a written Hz.

Higher sample rates, like 44 100 Hz, or 44.

1 kHz, capture more detail, making the sound seem more natural.

Lower sample rates might miss out on high frequency details, which can affect the clarity of the sound.

In terms of file size, higher sample rates result in larger files.

Let's have a quick check.

Which of the following is true about bit depth and sample rates in digital sounds? A, increasing the bit depth does not affect the file size, b, increasing the sample rate captures more detail but doesn't affect the file size, or is it c, increasing both bit depth and sample rate improves the sound quality but also the file size? Take your time to think about the answer.

You can pause the video or rewind it at any time.

Let's look at the answer.

It is c, increasing both bit depth and sample rate improves the sound quality but also increases the file size.

I hope you got the answer right, but don't worry if you didn't.

We can always move on or you can always rewind the video and look at some slides again.

Let's have a practise.

1, a professional recording studio produces music for concerts.

Why might they prioritise sound quality over file size? 2, a game developer needs background sound effects for a mobile app.

How might larger audio file sizes impact the player's experience? 3, a small business wants to add background music to their website.

Should they prioritise file size for faster loading or quality? Take a think about your answers.

Remember, you can pause the video at any time or rewind it to different slides that you want to look at again.

Let's have a look at the answer.

So 1, so this is about a professional recording studio producing music for concerts.

Why might they prioritise sound quality over file size? A sample answer could be, a recording studio prioritises sound quality because the music needs to be as clear and detailed as possible for the live performances.

A higher sample rate, like 44 100 Hz, or 44.

1 kHz, captures more detail, making sound more natural and parts are not lost.

Although higher sample rates create larger file sizes, this is not a concern in a professional recording studio where quality is the top priority.

So hopefully you got answers similar to that.

So let's have a look at 2.

A game developer needs background sound effects for a mobile app.

How might large audio file sizes impact the gamer's experience? A sample answer could be, large audio files can affect a player's experience in several ways.

Firstly, they take up more storage space on the device, which might be a problem for users with limited storage.

Secondly, playing these large files require more processing power, which could slow down the app's performance.

Lastly, larger files take longer to download or stream, which might frustrate users who want to start playing quickly.

So hopefully you've covered most of those points.

That's really good, really well done.

3, a small business wants to add background music to the website.

Should they prioritise file size for faster loading or quality? So the sample answer here is, the small business should prioritise a smaller file size to ensure faster website loading, especially for users with slower internet connections.

Excellent.

Well done for getting this far.

And hopefully you've got these answers correct.

Well done.

You are doing brilliantly.

We're going to move on to the second part of the lesson now, edit and manipulate sound files.

I'm really looking forward to this part.

This is where I can show you how to edit and manipulate sound files, and hopefully you'll be able to go and do the same yourselves.

Let's have a look.

Sam's asking, "Why is it useful for me to learn about editing sound files? I'm not into music." Sofia's reply, "It's not just for musicians.

Think about making a podcast, editing audio for a school project, or even adding sound effects to a video.

It's a skill that lets you be more creative and produce more polished, professional work, no matter the project." And she's right.

It's going to be amazing to learn these skills and to apply it in different ways.

We're gonna be using a programme called Audacity, but there's lots of different other software you could create, and edit, manipulate sound.

In this particular lesson, we're gonna be using Audacity 3.

7.

1.

But if you have earlier or maybe even more up-to-date versions, that's fine too.

Let's have a quick check.

What's the main purpose of sound editing software like Audacity? Is it a, to create text documents and presentations, b, to draw and edit images and photos, or c, to record, edit, and manipulate sound files? Remember, you can pause the video anytime or rewind it.

So the answer is c, to record, edit, and manipulate sound files.

This is a mono sound file with one channel and one waveform.

So you've got three of the keywords highlighted here in bold.

So it's mono because then using one channel.

So that's the same sound will come out of the right and left speaker or headphone.

The sound file is represented as a sound wave known as the waveform.

Now this is a stereo sound file with two channels and two waveforms. So you could manipulate this so that sound is different in the right and left speaker or headphone.

This is known as a stereo sound file.

In Audacity, the Transport toolbar, shown here, is used to pause, play, skip to start, skip to end, record, and loop a sound file.

So those are the different buttons that are available to you on the Audacity Transport toolbar.

The Tools and Edit toolbars can be used to select sections of the sound file, zoom in and out, trim, and silence part of the sound file.

So you can see them there in the middle of that screenshot.

The audio settings in the Audio Setup menu show different things.

So it shows the channels that's gonna be recorded.

In this case, it's one, so that's mono.

It looks at the sample rate, the sample format.

And all these settings can be changed to suit your project, whether it's background music on a website or a real professional recording for a podcast.

Switching to stereo, which uses two channels, doubles the file size but provides a more immersive sound experience.

Increasing the sample rate captures more detail, but it also increases the file size and requires more processing power.

Lowering the sample rate makes the file size smaller but might lead to noticeable quality loss.

So again, referring back to the first part of the lesson, where we are balancing size and quality.

A higher bit depth offers more detail but also increases the file size.

Lower bit depths are suitable for standard quality projects, like podcasts or online content, and helps save storage space.

This shows the Audacity Transport toolbar being used.

So you can see we can press play, which plays the track.

We can pause.

We can play again, which starts from the beginning.

We can stop the track.

We can go to the end of the track or back to the start of the track.

And now we're highlighting an area.

So a section of the waveform is selected and played.

This is known as selective playback.

To delete a section of audio, use the selection tool and click and drag over the area you want to remove.

Then select Edit and Delete from the menu or simply press the delete key on your keyboard.

So this screenshot is showing that last piece of sound on the sound wave being deleted.

To move a section of audio, use the selection tool and click and drag over the area you want to move.

Then select Edit and Cut from the menu or simply right click and select Cut.

Click on the position that you want the audio to be to insert it.

Then select Edit and Paste from the menu or simply right-click and select Paste.

Audacity projects are saved in a.

aup3 format and can only be opened and edited within Audacity.

This format is ideal for ongoing editing as it keeps all the project details.

To share your work with others or use it in other applications, you need to convert it into a widely compatible audio format.

Exporting your project ensures that your audio can be played on most devices or platforms. Two widely compatible formats are WAV, or.

wav files.

These are high quality format suitable for professional use, like audio editing.

They're also used for music production, mastering, and situations where audio quality is very important.

Another compatible format is MP3, or.

mp3.

This is a format that balances quality and a smaller file size for sharing online or portable devices.

It's used for streaming and podcasts a lot.

When the audio has been manipulated, you have two options, to reduce the quality of the sound file or to keep the current quality.

To export, select the File and Export from the menu.

From here, you can select a format.

Exporting it in a format like MP3 creates a smaller file than to a WAV but with a slight reduction in quality.

Select the sample rate in Hertz.

Selecting a lower sample rate, for example, 20 050 Hz instead of 44 100 Hz, reduces the detail in sound, resulting in a smaller file size.

Let's have a check.

Which of the following is true about Audacity project files,.

aup3 files? Is it a, they can be opened and played in any media player, b, they can only be opened in Audacity, or c, they are the same as MP3 files.

Remember, you can pause the video anytime or rewind it.

Let's see the answer.

It is b, they can only be opened in Audacity.

Well done.

Time for a practise.

1, what is the purpose of the Transport toolbar in Audacity? 2, where would you change the sample rate and sample format in Audacity? 3, how are stereo digital sound files different from a mono digital sound file? Want to pause the video at any time or you can rewind it to look at the other slides before this.

Time to look at some sample answers.

You're doing really well.

Hopefully your answers are very similar to this.

But don't worry if you're missing parts of each answer.

So 1, what is the purpose of the Transport toolbar in Audacity? So a sample answer is, the Transport toolbar is used to control playback, such as playing, pausing, stopping, and recording the sound file.

2, where would you change the sample rate and sample format in audacity? We can change that in the Audio Setup menu.

3, how are stereo digital sound files different from mono digital sound files? So stereo digital sound files have two channels, two waveforms, while a mono digital sound file has one channel, one waveform.

So stereo, you can have it so you have different sounds coming out of the left and right speaker or headphone.

But the mono, you don't.

It's the same waveform coming out of both the left and right speaker or headphone.

Well done on getting these correct and having a good go at them.

We have a fourth practise question.

Download and open the count.

mp3 file in Audacity.

This file counts from 1 to 10, so you can record your own voice if you want to in your own audio editing manipulation software or you can use the count.

mp3 file alongside this lesson.

A, trim the file so that it stops once it has counted to five, b, add to the end of the sound file to make it count down from five to one, change the sample rate and bit depth of the sound file, d, export the edited sound file in both WAV and MP3 formats, and then e, compare the file sizes of the exported files.

Which format has a smaller file size and why? So this is a very practical question and task for you to do.

So you can pause the video at any time, or if you want to look and see how to do certain parts, rewind it to the specific slides.

Let's have a look at a sample answer for e.

So hopefully you've done all the rest of the tasks yourself.

Well done brilliantly.

So a sample answer for e is the MP3 file will be smaller than the WAV file.

This is because MP3 is designed to balance sound quality with a smaller file size, which is useful for sharing online or storing on portable devices.

WAV files are typically larger because they prioritise high quality sound, which requires more data to be stored.

So hopefully you got a similar answer to this and got most of these points.

You're doing really well.

Well done, it's the end of the lesson.

So in summary, sound editing software allows you to change and export digital audio files.

Adjusting the attributes of an audio file, such as the sample rate and bit depth, changes how you perceive its quality.

For example, you can set the channel to mono for a single track or stereo for a two-channel sound to explore how these affect the audio output.

Well done.

I really enjoyed this lesson, and hopefully you have too.