Physics – Buxman Audio Mixing Lab
1. Recording Your Voice
Launch Program – Double click Cool Edit Pro on the desktop
Plug in microphone – should be in correct port on left side of computer. Press button on microphone in to record
Open a new File – File menu – New, Choose Mono
Record something Click the small red dot button (bottom left of screen) to begin and end recording Click the play button to play back your recording If you don’t like your recording, try again. Delete what you have recorded and re-record.
View the Waveform Using the yellow magnifying glasses, you can zoom in on the waveform or zoom out to see more or less detail. Zoom in until you see individual wavelengths. Zoom back out to full view.
Transform Options In the transform menu, there are many options to alter the waveform. First experiment with the wave features we know about. Amplitude is related to loudness – selecting Transform, Amplitude, Amplify will allow you to increase or decrease the amplitude. Frequency is related to pitch – selecting Transform, Time/Pitch, Stretch will allow you to either increase the frequency of the wave, or increase the speed of playback
Play with each of these features on your recording. After each transformation, look at a zoomed in view of the waveform and sketch or describe it in your lab notebook. Make sure to describe how each transformation affects the original wave
Play with some of the other transform options. Many of the transform windows have a preview button that will apply the transform and let you hear it immediately while changing the options. Things to try include Time/Pitch – Pitch Bender Reverse Delay Effects - All
Include a description of 4-5 transforms in your lab notebook. Physics – Buxman Audio Mixing Lab Tuning Fork Analysis Record a sample of a tuning fork. This should be a pure sine wave. Zoom in to see the detailed wave. Calculate the frequency of the sound from the graph. Remember, frequency is #waves/second. How does this compare to the frequency stamped on the tuning fork? Calculate a percentage error.
Frequency Analysis In the Analyze menu, choose Frequency Analysis. This window can be left open while playing your sample. The frequency window will show how much of each individual frequency is present. Play the tuning fork sample. Do the frequencies displayed in the frequency analysis window agree with a) what you hear, b) what you calculated above, c) what is stamped on the tuning fork? Discuss any differences.
Create a ‘pure sine wave’ with your voice Try to create a sound with your voice that is like the tuning fork. Sing, hum or whistle. Calculate the frequency of your voice. Describe how the waveforms of your voice and the tuning fork are different. Describe how the frequency analysis of the two waves compare.
2. Mixing Waves Create a new file: File menu – New, this time choose Stereo. You will see a screen with an upper and lower area. These are left and right channel. Move your mouse towards the top of the screen and your cursor changes to an ‘L’. Moving the mouse towards the bottom and cursor is an ‘R’. In the middle the cursor is regular.
In the left channel, use the Generate Menu and Tones. This feature will generate a pure 440 Hz tone. Play this sample to make sure that you have the right sound.
In the right channel, use the Generate Menu and Tones. Generate a 450 Hz tone in this channel. Play each channel separately. Then play both channels together. What do you hear?
Mix the waves together to see what the combined waveform looks like. To do this Select Edit, Insert into Multitrack (or Ctrl-M) Select View, Multitrack View (or F12) Select Edit, Mix Down, All Waves (Mono)
The new wave you now see is the combination of the two original waves. Zoom in view the waveforms. Describe what you see, what you hear, and what the frequency analysis looks like.
Calculate the beat frequency of this mixed wave using the values of frequency you use for generation above (recall fbeat = f1 – f2). Calculate the beat frequency of the mixed wave using the zoom feature and numbers on the waveform. Calculate a percentage error.