ORACLE


I came across
ORACLE ThinkQuest looking for information on Acoustics Sound and Psychoacustics. Here is a good study course for sound, always Important to musicians. Below is a sample of information offered at ORACLE Think Quest.


Introduction

For most of us, there are few moments in our life that are completely absent of sound. Sound is all around us, so much so that we can take it for granted. Sound waves have many applications, though, the most notable of which is probably sonar, which locates objects by bouncing sound waves off them.

In this section of Wave Express we will discuss how sound moves and the aspects of sound waves that affect how we hear noises. We will explore acoustics, exploring what an architect might take into account when designing a concert hall. We will delve into harmonics and resonance, and to put everything in its historical context, we will begin with an account of the history of the study of sound.

Another example

Harmonics

The frequencies at which standing waves can exist in a given rope with each end fixed are the natural frequencies or resonant frequencies of that rope. A rope, a spring and even the air in an air column have many natural frequencies, which are often labeled harmonics.

The first harmonic is the simplest mode of vibration and accounts for the fundamental tone. In a rope this means that the rope moves in only one segment, like a jump rope. Overtones are the modes of vibrations that a string, in this case, vibrates in more than one segment.

The second harmonic produces the first overtone.

The third harmonic produces the second overtone, and so on. In a rope with both ends tied there are only certain ways that this can occur, the frequencies of the overtones are whole number multiples of the fundamental frequency. Almost all vibrating objects produce overtones, which combine with the fundamental. One reason that tuning forks are so important to the study of sound is that their overtones vanish quickly, leaving only the fundamental.

The appearance of a wave, its waveform, is determined by the number and relative intensity levels of the harmonics in its vibration. The quality of the sound, important to music and other things, is a function of its overtones.

Air columns, such as those in musical instruments, have many harmonics. In a pipe with one side open and one side closed, the wavelength of the fundamental is four times the length of the pipe. Using the wave equation, we can see that the corresponding fundamental frequency is the velocity of sound in air divided by four times the length of the pipe. The first three harmonics of such a pipe are illustrated below. As you can see, a pipe with one side open and one side closed has only the odd harmonics.



ORACLE ThinkQuest: http://library.thinkquest.org/C005705/English/sound/sound4.htm


If you have an interest in Sound acoustics check out this site. The above writing is but a tiny fraction of what is offered about sound - acoustics - harmony - harmonics - beats - resonance - waves……….