instrument notes

computer analysis

calculator analysis

computer synthesis

web synthesis

calculator synthesis

scale and envelope

samples

beats

 

 

 

 

 

Music is one of the most interesting aspects of sound. Free sound editors like Audacity allow for detailed exploration of many of the features of sound. Before you continue, download and install a copy of Audacity on your computer. There are versions for Windows, Linux and Mac. Logger Pro is also very useful for general analysis of science data.

Simple musical instruments should now be accessible to any group. Calculator based logging allows for group work by the whole class. The following shows sound captured from a cheap electronic keyboard at low C, mid C and high C. While the display seems ragged in today's terms, the data is good and if imported into Logger Pro the display appears smoother. A Logger Pro file of the calculator captured data is here.

     

     

     

Listen to the example of high C by downloading into Audacity this compressed file (10 k) or this standard wav file (ca. 100 k)

Identify the mid C low C and high C. It seems that this is not the same simple smooth waveform obtained from whistles or tuning forks. The vibrations are more complicated. Which is the most complicated? Why might this be?

If this is the default waveform capture using the Physics App then 100 samples have been collected at 10000 samples per second. So estimate the time for one waveform and so the main frequency for each of these. Take the value measured for the speed of sound and so calculate the wavelength.

Capturing sound from an old domestic piano at high C and mid C:

     

     

Listen to the high C in a compressed format here (15 k) or as a standard wav file (100 k). You can see and hear that this piano needs attention.

These files can be played in your Audacity software. These show a similarity to the sounds from the keyboard. Estimate the frequency again - simply compare the number of waves with those in the keyboard examples.

The keyboard was played while set to mimic the piano. If set to other instruments then different shaped waves are captured. So in music not only the frequency (p....) and Amplitude (l.......) are important in defining the sound but also the detail of the wave shape.

This is called the quality of the sound. What contributes to the quality of the sound and how can electronic instruments mimic real instruments?

Now we need to look at sounds made by different instruments at the same pitch. Are there clear differences between classes of instrument: wind, wood, brass?