1. Investigating the sound quality of different audio file formats In this activity, we are going to record a short voice sample with a sound recording tool, Audioblast. The digital audio files are saved in both WAV and MP3 formats with different bit resolutions. The sound quality and file sizes of these files are then compared. We will also explore the applications of different audio file formats and settings. Activity 3 Audioblast

2. Investigating the sound quality of different audio file formats Procedure 1.Download and install Audioblast from the following web site: http://www.moor-software.com or http://www.download.com http://www.moor-software.comhttp://www.download.com 2.Run Audioblast. 3.Select ‘File’ → ‘New’ → ‘Empty’ to open a new file. 4.Select ‘File’ → ‘Property’ to set the audio file properties as follows: Activity 3 Bitrate = 16-bit Frequency = 44,100 Hz Type = Stereo

3. Investigating the sound quality of different audio file formats Procedure 5.Press the ‘Record’ button ● to start recording your voice sample for about 10 seconds. Press ■ to stop. (Adjust the microphone settings in the Windows Volume Control if necessary.) 6.Select ‘File’ → ‘Save’ to save your recorded sample in WAV format as test1.wav. 7.Select ‘File’ → ‘Export’. Set ‘Bitrate’ as ‘32-bit’ and ‘Type’ as ‘Stereo’ to export your recorded sample in MP3 format as test32.mp3. 8.Select ‘File’ → ‘Export’. Set ‘Bitrate’ as ‘128-bit’ and ‘Type’ as ‘Stereo’ to export your recorded sample again in MP3 format as test128.mp3. Activity 3

4. Investigating the sound quality of different audio file formats Procedure 9.Play the three audio files with Windows Media Player. Compare the quality of each one and write down their file sizes. Can you judge their quality easily? State some factors that will affect your judgement. Activity 3 File Quality of sound 1 (best) to 9 (worst) File size (KB) test1.wav test32.mp3 test128.mp3

5. Investigating the sound quality of different audio file formats Procedure 10. Comment on their qualities and file sizes of test1.wav and test128.mp3. Suggest one application for each audio file format. _________________________________________________________ Activity 3 The quality of test1.wav is better than that of test128.mp3 while the file size of test1.wav is larger than that of test128.mp3. test1.wav can be a recording of a classical song in a CD while test128.mp3 can be a song which is transmitted over the Internet.

6. Investigating the sound quality of different audio file formats Procedure 10. Comment on their qualities and file sizes of test1.wav and test128.mp3. Suggest one application for each audio file format. _________________________________________________________ Activity 3 The quality of test1.wav is better than that of test128.mp3 while the file size of test1.wav is larger than that of test128.mp3. test1.wav can be a recording of a classical song in a CD while test128.mp3 can be a song which is transmitted over the Internet.