The video titled Musical Acoustics and Sound Perception, is a taped presentation in which Williams College physics professor, Tiku Majumder, gave an insightful picture into the complex beauty that is sound. There are many ways to consider sound. Some people study music, others consider it from a biological or medical or even physical standpoint. Such is the case in this presentation, where the focus is all about the physics of sound moreso than the anatomy that processes it. The speaker made the topic all the more interesting by presenting information in the context of examples. As sound is such an abstract concept One of my favorite examples used the video, were the oscillations shown using rope to describe sinusoidal movement. While this was a simplified way of explaining soundwaves in layman’s terms, like in many other examples utilized in the video, he then expounded on the idea by describing the pressure changes that occur in soundwaves and forcefully propagate them, or move them, in a systematic way through matter as working much like a slinky. As he built on this topic and figures became came more and more dimensional, he demonstrated that sound is all about interaction among waveforms and how they are pushed through the matter. The characteristics of said matter is what determines the characteristics of the sound. And, through these mechanisms the human ear is able to decode the sounds and then associate them with this particular source.
The human ear is not the only interesting physiologic structures involved in this discussion about sound. The system through which human beings speak and communicate is equally as fascinating in terms of sound properties. Essentially, from the perspective of physics, the vocal cords, chest, lungs, teeth, tongue and many other structural features of the breathing passageway all use coordinated movements to produce sound much like an extremely complex instrument. Vowels in particular are similar to musical content because of a term: a harmonic.
As sound waves propagate via a longitudinal wave which moves from right to left (or left to right depending on the sound source) instead of a transverse wave, which moves up and down. As the sounds propogate, they interact. If two pulses join together, they add up. Amplitude is not the only way sounds can interact which brings the discussion back to harmonics. As multiple simple pure tone sounds interact there is always a fundamental frequency or vibration rate that underlies all others. As other layers are dropped on top of this fundamental frequency they create additional levels of the sound called harmonics. Ultimately, the most important thing to remember is that sound is related always to vibration and whatever object it vibrates flavors the sound.
Another very important issue in the physics of sound was emphasized in this video. That is, the idea that human beings can recognize different sources of a sound based on its physical properties. We can tell the difference between a cat meowing and a dog barking quite easily even if they are using similar pitches, or frequencies, to make up their meow or bark respectively. Thus, there must be more to sound than how loud or how shrill or deep it is. Another aspect is called timbre, which some define as the characteristic of a particular musical sound. Essentially, timbre represents the difference we can hear between a flute, a piano and a guitar that are playing the same note. Timbre is all about the spectrum of particular sounds or musical styling’s. It is a perceptual manifestation of all of the complex physical properties that exist within the world today.
- Majumder, T. (2011). Musical Acoustics and Sound Perception, Retrieved on April 18, 2016 from: https://youtu.be/mBpnIrBNoxs.
