Using Audio to Enhance Teaching and Learning Editing audio with Audacity

Transcription

1 Using Audio to Enhance Teaching and Learning Editing audio with Audacity Basic editing of a recording To edit a recording in Audacity you can use same type of actions that you can use in most computer applications, such as selecting, copying, pasting and deleting. Copying part of a sample 1. Make sure the selection tool is active by clicking on it. 2. Click and drag over a part of the audio sample Figure 1 Selecting part of a sample 3. Select Edit and Copy 4. Click on the sample where you want to add the copy 5. Select Edit and Paste Figure 2 Copying selection into another part of the timeline 6. The copied piece of the audio should now be added to the timeline. 7. Press play to listen to the recording now. Remember you can highlight a portion of the sample before so only that part of the track plays. 1

2 Moving part of a sample 1. Highlight the part of your sample you want to move 2. Select Edit and Cut 3. Click on the new position you want that piece of audio to start 4. Select Edit and Paste Deleting part of a sample To remove a part of the waveform completely 1. Highlight it and hit the delete key Figure 3 Selecting part of the timeline Figure 4 Selection deleted from the timeline 2. If you make a mistake you undo it by selecting Edit and Undo. When you are making a recording and you make a mistake part way through it, you don t need to stop recording and repeat it from the beginning. You can just repeat the part you got wrong and then edit the track afterwards. 2

3 Working with Multiple Tracks When you are making a recording you might actually complete it in a number of sections. Each time you stop and start a new recording, Audacity creates a new track. Only if you pause your recording and then resume it, will it continue on a single track 1. Using your existing recording click on the timeline where you want the next part of the recording to begin. 2. Click record. The new piece of audio will appear in a new track. Figure 5 New recording added to a new track 3. Name the two separate tracks. Click on the word audio track then select Name, and enter a name. This becomes important to manage your track and remember what each one contains. Figure 6 Naming Tracks 3

4 4. You can move the audio in one of the tracks relative to the others. Select the Time Shift Tool. Click and drag on the audio sample in a track and move it to the left or right. Time Shift Tool Sample can be moved left or right Figure 7 Moving the position of a sample in a track 5. To delete an entire track click on the close button in the top left hand corner of the track window. Delete Track Button Figure 8 Deleting an Audio track Saving audio information with your MP3 When you are happy with the edited audio, you need to export it into MP3 format. 1. Select File then Export as MP3 2. Give it a name and click Save 3. Another box will appear requesting additional information about the MP3. Enter details about the title, ownership, content, year etc. (You can use Speech as the Genre for the audio if none of the other categories are suitable). 4. Click OK to confirm the details. Be aware that this information (called metadata) is available for anyone to view when the audio is player on a computer or device. 4

5 Enhancing the Quality of the Recording Increasing / Decreasing the Volume If the volume of your recording is at the wrong level, Audacity has editing tools for amplification and noise reduction. The previous tutorial showed you how to amplify an entire track. This approach shows you how to do it more precisely and also allow you to amplify just specific parts of the sample. 1. Highlight a section of the sample you want to amplify 2. Select Effect then Amplify 3. The amplify settings box appears with the suggested value to use. This value will not exceed the 0dB maximum and cause distortion of the audio. 4. Click OK to confirm Figure 10 Amplify Settings 5. To decrease the volume, also select Effect and Amplify but put a negative value into the Settings window which appears. Figure 11 Sample before amplification Figure 12 Sample after amplification 5

6 Removing noise If the quality of your microphone is poor, it may pick up some background noise in your recording. This can become very obvious when you amplify you recording. To remove noise 1. Select a small piece of the recording that is silent except for the noise. 2. Select Effect then Noise Removal and click on the Get Noise Profile button Highlight silent part of sample Figure 13 Selecting silent of sample 3. Select all of the audio you want noise removed 4. Reselect Effect then Noise Removal and click the Remove Noise button. 5. Use the slider to remove more or less noise. Select all or part of sample for noise removal Slider to adjust level of noise removal Figure 14 Selecting part of sample for Noise Removal Further Editing Techniques Noise removal does result in some distortion of the audio and should only be used as a last resort. A poor original sample can be difficult to improve and it is more important to ensure that you recording levels for your microphone are correctly set. 6

7 Additional Editing Techniques Editing existing MP3 files You can use Audacity to edit existing files in a range of format. To edit one of your existing MP3 files it can be imported into Audacity if you no longer have the original version. However, the MP3 file will only consist of a single track. 1. Select File then Open and locate one of your existing MP3 files. 2. Edit the sample using the previous techniques. 3. Select Project then Edit ID3 tags. 4. Edit the additional information. For the MP3 file then click OK to confirm. 5. To save the changes you must use select File then Export as MP3. If you just save the project it will just create an Audacity file. Using music in your recording Some professional podcasts use music as an introduction or at key points. You need to be careful when incorporating music as most commercially recorded music is copyright and not legally be used. If in doubt do not use it. Royalty free music and audio is available under the Creative Commons agreement. 1. Download an audio file. 2. Open one of your existing audio recordings. 3. Select Project then Import Audio and locate the music file. Figure 15 Imported Music tracks The music was recorded in stereo so two audio samples appear in the track. 7

8 4. Use the Time Shift Tool to move your audio sample along so it starts after the music has ended the beginning. Time Shift Tool Figure 16 Moving the narration audio 5. If the intro is too long, you can delete part of it. 6. Export the sample as an MP3. All the tracks will automatically be compressed into one track. The music starts and then ends abruptly before the narration begins. This can be overcome by the use of fading. Use of Fading To make the music start gradually and the volume build up you can use the Fade In effect. 1. Select the area of the sample to fade in. This is normally done over a few seconds Portion selected for fade in Figure 17 Selecting the first few second of the music sample 8

9 2. From the menu, select Effect then Fade In. 3. The sample will change to show its volume gradually increasing from the start. 4. At the end of the music sample, select a part to fade out. 5. From the menu, select Effect then Fade Out. 6. The sample will change to reflect this. 7. Now when you play the recording, the musical intro will gradually fade up and then fade down before the narration starts. Music or sound effects can be added to any part of the timeline. Music and Copyright Figure 19 Music sample with a fade in applied Most commercially recorded music is copyright and not able to be used within a podcast. However, Creative Commons material can often be used for educational purposes, but terms of use should always be checked. If in doubt do not use the music. Some Internet browsers allow you to search directly for Creative Common material. Firefox allows you to customise your searching from the drop down list. Figure 20 Selecting the Creative Commons search function 9