Digital Audio Recording PDF

## 5.2 Digital Audio Recording ### In this lesson You will learn: - how computers record sound digitally - how to make sound recordings using multi-track audio software. ### How is sound captured digitally? Sound is movement of the air. The air moves in a wave pattern called sound waves. Our ear...

## 5.2 Digital Audio Recording ### In this lesson You will learn: - how computers record sound digitally - how to make sound recordings using multi-track audio software. ### How is sound captured digitally? Sound is movement of the air. The air moves in a wave pattern called sound waves. Our ears can detect these sound waves. A microphone can also detect sound waves. A microphone has a part that vibrates when sound waves hit it. In most microphones the part that vibrates is a diaphragm. The microphone also has an electromagnet that generates electricity when the diaphragm vibrates. A computer converts the electricity to a digital signal. 1. A microphone converts sound waves into electricity. 2. A computer converts the electrical current into digital data. It stores the data. It can play the sound by converting the data back into electricity. 3. Headphones or loudspeakers turn the electrical current back into sound waves you can hear. ## Digital Audio Formats The table lists some common audio file types and describes their features and uses. | File type | Filename extension | Features | Used For... | |---|---|---|---| | WAV | .wav | Stores audio accurately and with high quality. WAV files can be very large so they can take a long time to copy and process. Not suitable for portable players or streaming. | high-quality recording of audio such as music and speech. The WAV format is used in professional recording studios. | | MP3 | .mp3 | Uses much less storage space than WAV. MP3 files are compressed, so there is some loss of audio quality. You can vary the amount of compression to make file sizes smaller. | storing and playing back audio on personal devices; streaming audio over the internet. Professionally recorded music is often converted to MP3 for distribution to listeners.| | FLAC | .flac | Provides lossless compression - file sizes are reduced but there is no loss of quality.| storing and playing audio on personal devices such as laptops and PCs. It can be converted to MP3 for streaming later. | In the example in this unit, sound is recorded as a WAV file. It can be converted to MP3 for streaming later. ## How to use your computer to record sound To begin recording sound, you need a microphone connected to your computer. Different microphones are appropriate in different circumstances. | Microphone | Features | Used For... | |---|---|---| | External microphone (condenser type) | High-quality audio capture. Very sensitive to background noise, so needs a quiet environment. | high-quality audio from voice or instruments | | External microphone (headset) | Medium-quality audio capture or professional-quality for broadcasting. Must be positioned close to the speaker's mouth, so it can only pick up sound from one person. | internet voice communications broadcasting such as sports commentary | | Internal microphone (laptop, tablet, smartphone) | Medium-quality audio capture. Laptop microphones can capture sound from more than one person - but also pick up some background noise. | internet voice communications| ## Digital Audio Recording ### Recording software Many computers and smartphones have simple voice recorders that allow you to record a single piece of audio. These apps offer very few options to edit the sound. They can only record and play back one track of audio. To create a podcast featuring more than one voice, you will need to record more than one track. Each track can contain pieces of audio called clips. You can arrange and mix the tracks together to create your final audio project. This process is called multi-track recording and editing. The software you use for this is often called a digital audio workstation (DAW). ### Choosing a digital audio workstation (DAW) Many audio-editing apps are free to download and use, such as Audacity, WavePad, Ocenaudio and Wavosaur for Windows or GarageBand for iOS. The example in this unit uses the Audacity DAW. You can use any multi-track DAW that works on your device. ### Using a DAW Most DAWs have a screen that shows the sound in your project as waveforms. The waveforms are arranged into different tracks (from top to bottom) along a timeline (from left to right). A cursor moves from left to right as you play the sound. The cursor is usually shown as a line across all the tracks. The transport controls move the cursor to the beginning or end of the project. Use the 'Play' button to start playback or press the keyboard space bar. The 'Record' button starts the recording. The input level meter helps you control the sound levels. The timeline is shown across the top of the screen. The clips of audio you record are shown as waveforms in tracks. The cursor moves across the screen as the sound is played in each track. ### Set the recording levels Make sure that your microphone and speakers or headphones are correctly set up. 1. Click in the area of the screen with the input level meter. 2. Speak into the microphone in your normal voice. 3. While you are speaking, move the recording volume slider until the green lines reach about two-thirds of the way across the meter. ### Making a recording Click on the 'Record' button and begin speaking. The cursor will start to move from left to right and a waveform graphic will appear. The waveform shows the sound you are recording. When you have finished recording, click 'Stop'. To listen to your track, move the cursor to the beginning of the project and click 'Play'. ### Activity Make a test recording. - Set up your microphone. Check the input level meter until you are happy with the level. - Record one minute of test audio. Choose a segment of your podcast. Use the outline and the script you created in the last lesson. - Stop the recording and listen to it. - Write down any changes and improvements you would like to make in the final recording. ### Extra challenge Record a second test segment. - Add a new track from the 'Tracks' menu and place the cursor in the new track area, at the end of the timeline. - Record your second test segment. ### Test 1. In your DAW, what does the waveform illustrate? 2. Write down this sentence and fill in the gaps: "A microphone converts ______ into _______." 3. How does an imput level meter help you record audio? 4. Explain the difference between an audio track and an audio clip.