Sound is Vibration
Introduction
Sound is a form of energy that travels through matter as a wave. When an object vibrates, it causes the surrounding air molecules to vibrate as well. This creates pressure waves that travel through the air as sound.
The properties of sound waves can be described in terms of their frequency and amplitude. Frequency refers to the number of waves that pass a fixed point in a given period of time and is measured in Hertz (Hz). Amplitude is the height of the sound wave and determines the volume or loudness of the sound.
When sound waves encounter an object, they can be reflected, absorbed, or transmitted through the object, depending on the properties of the object and the sound wave. For example, sound waves are reflected by hard, smooth surfaces like walls and floors, while they are absorbed by soft materials like curtains and carpets.
Notes
Wednesday - Practical Proect - Cubase
Cubase is a digital audio workstation software. It is designed for recording, editing, and mixing music and other audio projects. The software has a wide range of tools and features for audio production. Cubase is used by musicians, producers, and audio engineers in a variety of genres, from electronic music to classical and film scoring.
（shot in G3027)
In the second half of the course, we were asked to work through Cubase with the provided audio files. This was interesting and challenging for me as I had never been involved with it before.
I selected several audio files which included the sound of a noisy crowd, the sound of a running water, the sound of ice, the sound of a gun, the sound of a helicopter. The audio was created by means of editing, repetition, delay, EQ enhancement, distortion etc. The hope was to create a narrative environment: the protagonist fleeing in his car to a tavern after firing two shots on the highway, panicking through a noisy crowd.
Lab experiments
water&vibration
Case
In the case of water, when a sound wave passes through water, it causes the water molecules(水分子) to vibrate. When the frequency of the sound wave is the same as or close to the intrinsic vibrational frequency of the water molecules, the sound wave can cause the water molecules to resonate（共振）, causing the amplitude of the water molecules to increase, resulting in a greater impact. This phenomenon is called acoustic resonance（声波共振）. On the other hand, when the frequency of the sound wave does not match the intrinsic vibration frequency of the water molecules, the interaction is relatively weak and the effect is relatively small.
Therefore, different frequencies of sound waves have different effects on water. For example, low frequency sound waves (20-100 Hz) may cause resonance of bubbles in the water, causing them to expand and burst, thus creating cavities and eddies(空洞和涡流) in the water.
Assignment 02 - Create a Sound Portrait
This assignment requires us to record and layer the sounds to create a soundscape artefact by using the experiments shown in the lecture.
My team member and I initially wanted to try to complete the experiment of making the straw in the cup move by changing the frequency of the sound. I used plastic cups of finished coffee and plastic straws as the materials for the experiment. The experiment took place in the quiet lounge of the school.
At the same time, we referenced the figures in the video, around 730HZ. I had thought the experiment would be very easy to complete. But instead we suffered a failure. No matter how the frequency value is adjusted, the straw in the cup does not move at all.
Video of the first experiment
Further study
There are many examples of visual art produced by altering sound waves, and Science photographer Linden Gledhill has created wonderful visual experiences through the use of water, neon lights and speakers.
The setup behind Gledhill’s marvellous soundscapes is simple. A reservoir of water sits atop a speaker, separated by a thin membrane. The speaker is driven by an amp, attached to a computer that runs sine wave-generating software. As sound waves pass out of the speaker, Gledhill photographs them from above, peering down at the surface of the water of the water through a ring of LED lights.
Speculation on the reasons for failure
After looking up the relevant information and watching the example video again, I believe that the following reasons may have contributed to the failure of the experiment.
1. The volume of the phone was too low to produce a high energy sound wave.
2. Material problems. The original video used a glass cup and a paper straw. The glass resonates with the frequency of the sound to produce the maximum vibration. This resulted in the straw being too weakly influenced by the sound waves to produce movement.
As it was too late to purchase new materials, the group and I decided to try a new experiment - to explore the effect of frequency changes on the movement of the candle flame.
Further Study
At the same time, the effect of frequency on people also aroused my interest. In the experiment, just listening to the 800hz sound for about five minutes made me and my group members feel uncomfortable. Could there be frequencies that are pleasant and healing in nature? Can this be applied to the project?
（More literature and cases will be studied further）
Second Experiment
This time we wanted to investigate the effect of frequency change on the candle flame.
As you can see in the video, the flame oscillates more significantly at around 250Hz. Despite being influenced by the airflow, we believe this is due to the sound frequency.
Video of Experiment2
Reference
Stone, M. (2016). These Images Of Sound Waves In Water Are Hypnotic. [online] Gizmodo Australia. Available at: https://www.gizmodo.com.au/2016/02/these-images-of-sound-waves-in-water-are-hypnotic/ [Accessed 4 Mar. 2023].
StudySmarter (n.d.). Resonance in Sound Waves: Definition & Example | StudySmarter. [online] StudySmarter US. Available at: https://www.studysmarter.us/explanations/physics/waves-physics/resonance-in-sound-waves/.