Hi, my name is Daniel Gallego, I am a musician and an artist, currently enrolled at the Introduction to Music Production course from Berklee College of music at coursera, and today I want to discuss two basic properties of sound, the way we collect them from nature, and the way we measure and interact with them in a production enviroment.
When a physical phenomenon: (say a guitar string) produces changes in the energy (it vibrates) of the molecules in a mechanical medium (the air) and depending on the media and the source of the energy change, (their physical properties: the make of the wood and the strings of the guitar, the skill of the player, the location of the instrument in space), this movement in the air, repeated over periods of time too brief and imperceptible for the human to notice, will eventually become waves, and reach our ears, where our brain will then interpret this a sound.
This sound, will have a few basic properties, a couple of which we can detect right away after hearing the guitar player plucks the string: Those properties of sound will be called pitch, and the other loudness or volume. That is, it will be high (violin), or low (tuba), and it will be loud (a hydraulic hammer) or quiet (a humming bird). These properties of the sound will be in fact conditioned by mechanical, or physical aspects of the source of the sound and its location in space. As we discussed earlier, this movement of the air molecules will be repeated over time in a manner imperceptible to the human ear, and the faster it repeats itself, the higher the pitch its going to be. The slower the sound source moves the air molecules, the lower the pitch its going to be. In western civilization we have divided this range into notes that musicians use to create scales, melodies and harmonies.
In this case, the pitch is controlled by the guitarist, choosing to pluck a more thin string or with the guitar frets, choosing to reduce the length of the string for a
HIGH note,
Or plucking a more thick string or allowing the string to have more length in order to obtain a LOW note.
If the Player plucks the guitar string softly, then the molecules of the air won’t be as much disturbed, and it won't be very loud, but if the player plucked the string more fiercely then the sound would be more loud. Player has also some degree of control over this aspect.
When this two concepts: pitch and loudness are measured by dedicated devices, which can take input directly from the environment, they are to be quantified: the pitch we perceived will then be measured in hertz(Hz, or once per second.), and be refered to as Frequency, refering to the frequency the wave takes to either compress (more air pressure) or rarefact (less air pressure) during a cycle; and the loudness, in decibels(dB) and will be referred to as Amplitude, referring to the amount the air molecules vary in intensity when propagating the pressure, if this intensity its too much, it will be more amplitude, and as such, it will seem louder to us. The human ear can detect and discern sounds that go from 20hz, or twenty cycles per second, to sounds that reach 20KHz, or twenty thousand cycles per second, although these are not exact value, as some people hear more or less range than others, and as we advance in age, our ears and brains seem to give
more importance to some of the frequencies, over the others. Even when both the terms refer to similar concepts, and are in fact related, mostly for reference, they are not entirely the same. Pitch and loudness are terms we use while addressing our human perception, and are subjective and related to our individual sensory system, for example, our guitar player may have great skills, but he might not know the exact Hz at which his pitch works. He might have an idea, say: “my A note is 440Hz� but due to properties of the make of the instrument, the air, the space he is located in, and the player himself, the frequency that arrives to our ears, and our machines detect might tell us otherwise. So, Frequency, measured in Hz = Hertz, and Amplitude, measured in dB = decibels, are the data that machines quantitatively detect and/or produce, according to the wavelength and intensity of compression and rarefaction of the sound wave.
As a musician the concepts of this first week are not unkown to me, but any chance is a good chance to reafirm your knowledge and help a fellow student grasp some of the basics behind, be it music itself (and physics), or its’s production. As the weeks go on I might find concepts more challenging or in need of update from my part. As I don’t have a lot of time to make a video, nor am I not the most charismatic guy on screen nor microphone I prefered a text and image aproach, I tried to spice it up and be exmplative with a couple of pics of myself and the guitar, making ir a relatable thing on the basic side, but nothing fancy; I guess nex time I would like to either have more time in my week, or do some kind of illustrations to better showcase the more abstract concepts. Thank you for reading the material, thought and effort went into the making of this document, and I hope I delivered the material and concepts in a clear and concise manner. Any comment and critique about both the content and presentation are welcomed!