Term 2 Module 3 PBL Report

Done by Fan Yi 3M308 Daniel Tan 3M306 Huang Jun Cheng 3M312

Problem statement

How the contours and surfaces of the room and the furniture in the room can affect sound quality and sound refraction and reflection, which in turn affects the range of audibility of the sound waves and the optimum range in which all the soundwaves can be heard instantaneously.

Final Concept Map

Relevant information and concepts

Relevant information / concepts

Reflection:
When a wave reaches the boundary between one medium another medium, a portion of the wave undergoes reflection and a portion of the wave undergoes transmission across the boundary. The amount of reflection is dependent upon the dissimilarity of the two medium. Thus, a hard material such as concrete is as dissimilar as can be to the air through which the sound moves; subsequently, most of the sound wave is reflected by the walls and little is absorbed. Walls and ceilings of concert halls are made softer materials such as fiberglass and acoustic tiles. These materials are more similar to air than concrete and thus have a greater ability to absorb sound. This gives the room more pleasing acoustic properties.

Diffraction:
Diffraction is the bending of waves around small obstacles and the spreading out of waves beyond small openings. Important parts of our experience with sound involve diffraction. The most common one is that we are able to hear things around corners, due to both diffraction and reflection of sound waves happening. Diffraction in such cases helps the sound to "bend around" the obstacles.
Diffraction also causes sound waves to spread out past small openings. This aspect of diffraction also has many implications. This allows people to hear sounds inside a room even if they are outside, this spreading out of sound waves has its bad sides as it causes problem when attempts to make a room soundproof.

Wave interference:
Wave interference is when one wave completely destroys another wave when they overlap, resulting in no sound at all. This can occur either due to the waves themselves or due to the special shape of the studio which makes the waves overlaps each other through reflection, diffraction.
Imagine two different waves, one with amplitude of +1 and another -1 moving towards each other, the two pulses will completely destroy each other when they overlap, resulting in no sound that can be heard, unless the two waves themselves cannot be heard originally, just like the process of neutralization except there's no water produced.

Relevant Data

Relevant data

When sound waves from the source hits a flat surface, it will bounced off to a direction opposite the where the original sound wave comes from. When sound waves hit a jagged surface, they will be reflected in all directions. When sound waves hit a porous surface, a large amount of it will not reflect back due to diffraction as they will filter through the porous surface, resulting in loss of sound waves and a lower frequency of sound waves being heard in the studio at any one time. However, when sound waves hit a concave surface such as the shape of a parabola, it will be reflected back to the source in the form of straight rays.
When designing the studio, we must be aware of wave interference, where one wave will completely destroy another wave when they overlap, resulting in no sound at all.

When sound waves hit a flat surface, it will be reflected depending on the angle the sound waves come from. There is no change in the frequency and speed of the sound waves as the medium in which the waves travel in is constant.
When sound waves hit a parabolic surface, they will be reflected directly back to the source of the sound waves.

Solutions

Solutions

1st solution - fewer furniture.
When there are more furntiture in a room, there will be more reflection of sound waves as there is a higher chance for the sound waves to be in contact with a material surface. However, with more reflections come the greater rate of sound waves being diminished, as sound waves lose their energy as their energy is absorbed by the surface it reacts with. The energy of the sound waves are also lost in the form of heat energy, which in turn causes the range of audibility of the sound waves to decrease exponentially. Therefore, there is a need for as little furniture in the studio as possible, so as to ensure there are less obstructions in the room for the sound waves. The furniture used should most preferably be made from materials with smooth surfaces, such as wood and cloth, so as to ensure a greater percentile of normal reflection as compared to diffused reflection of sound waves.

2nd solution - placement of furniture
By putting the furniture at the flat sides of the studio, if any, will ensure that any sound waves that is reflected to the flat sides of the studio will be reflected off towards the parabolic sides of the studio and thus ensuring a constantly great range of audibility in the studio due to the effective reflection of the sound waves towards the various corners of the room at any one time.

3rd solution - shape of room
When sound reflects off a special curved surface called a parabola, it will bounce out in a straight line no matter where it originally hits. Many stages are designed as parabolas so the sound will go directly into the audience, instead of bouncing around on stage. Thus we can have two studio designs, both utilizing the concept of parabolic surfaces to a certain extent. One possible design is to have a completely parabolic and round studio, while another design is to construct a studio with two opposite sides being flat and the other two sides parabolic.

Ellipse Studio-
Having an ellipse studio ensures that there will be more focus of sound waves as any sound that comes from the source will be reflected directly straight back towards the source of the sound waves, which will be the speakers located at the two ends of the studio. However, the sound will be mainly concentrated on two points, which are the focal points, in the studio. This, however, can be considered a plus point if he audience in the room and users of the room are specifically designated to position themselves in spaces where the sound waves are being focused in.

Partly Parabolic Studio-
Having a partly parabolic studio ensures that sound waves will be reflected everywhere in the studio, so that the sound can be heard in all parts of the studio. This is due to the sound waves reflecting off the flat surfaces towards the parabolic surface, and then the parabolic surface will reflect sound waves directly straight. The advantage is that there is more even spreading of sound and greater range of audibility for the users of the room at any position.

4th solution - type of speakers-

As sound travels faster in material mediums and mediums with higher optical density, due to the higher concentration of molecules and particles in the optically denser mediums, the addition of a layer of dense material such as a plastic coating will allow he sound waves to travel at a greater speed towards the designated direction, which increases the propagation and reflection of sound. The speakers should ideally be of a large surface area with very small pores, as this increases the diffraction and propagation of sound lateral-wise and thus increases the reflection of sound waves throughout the room. These implementations will ensure a greater audibility range, without compromising too much on the quality and the clarity of the sound waves being heard as there is still a minute amount of reflections and obstructions in the pathway of these sound waves.

5th solution - environmental factors of the studio-

As sound travels at a faster rate in an environment with higher humidity, it would be viable to ensure that the studio is enclosed most of the time so as to ensure that the sound waves will be able to reach the audience at a faster rate. Therefore, it is important for the studio to have a minimum of windows and ventilation for a better listening experience for the users of the studio. Having windspeed in the direction of the propagation of the sound waves will also ensure a faster rate of movement of the sound waves, but this is not entirely feasible as reflected sound waves travelling in other directions will be negatively affected by this source of interference, and thus lower the speed of the travelling wave. As a result, an enclosed space will little ventilation will be the best circumstances for the studio to be in.

Reflections

Reflection about the group

As a group, we feel that we have done quite well for our report. The fieldtrips the group had was very illuminating and we managed to put our learning from our fieldtrip in use. This had made us learn more about topics such as the reflection and diffraction of waves and we are able to apply them into the design of the studio as these concepts are important in ensuring a good studio.

Difficulties faced as a group and how the group went about solving them

The major difficulty is that communications between us is very very rare and difficult. Also, we need to constantly remind each other and it is very difficult to do a report together when we are unable to contact each other. Also, the design of the studio is a challenging task as we do not know how the shape affects the studio. We solve the first communication problem by constantly making use of online communication mediums such as MSN to discuss about our project. As for the how to design the studio, we researched on how the shape of the studio affects the studio by ways such as reflection of sound waves.

What the group did well

Although we had a late start and certain disagreements in designing the studio, we managed to come up with the design of the studio in the end and we all learnt the importance of teamwork and further improved our knowledge on sound waves.

What the group could have improved on

The group needs to do work at a constant pace, as there are times when the group simply stopped working while other times where there is a sudden rush in the work. Also, the group needs to research more about whether the material of the walls of the studio affects the audibility of the room.

Self-reflection

Fan Yi:
What skills you have learnt?
I have learnt to apply what I learnt in class into the project. I also learnt the skills of teamwork and thinking creatively.
How has your critical thinking skills been enhanced?
The project is made to make me think more about the topic as it requires thinking. I need to think whether the shape of the studio affects the audibility of the studio.
What difficulties did you face during the PB solving process and how did you go about solving them?
There are some concepts in which I am unsure of as some sources and I solve it by surfing the net to check out the concepts.
What further improvements could you have made?
I feel that I can be more proactive in my project and do not need my members to remind me. Also I think I need to remind my members some more as well.

Jun Cheng:
-- What skills have you learnt?
· Teamwork
- Definitely, as a working team of 3, we have gone through many meetings and discussions over the past few weekends and afternoons. We have recognised the fact that the workload has to be spread efficiently, as someone in the group might have tests coming while the others might not, so the workload has to be spread accordingly.
- During our discussions, we find it much easier compared to just working alone, as we get to find different opinions and share with each other. By doing so, we can help to modify and expand on one’s idea, producing the best and most effective ideas and solutions for the whole group.
- Also, we need a lot of cooperation to get things done quickly and fast. Therefore, our leader has been contacting us as a whole group when he decides to give a meeting, instead of just telling one person so as to prevent miscommunication.
-- How has your critical thinking skills been enhanced?
Our critical thinking has been enhanced mostly by the creating and tackling of the problem statements.
It is basically a two-stepped process -
1. Having different perspectives of the problem(what to be addressed)
- In the first place, it was a tiring and difficult thing to define the problem statements, as we had different views on what they should be. It could even take us an afternoon to complete a problem statement and expand on it until we all as a group accept and agree on it. And during the discussions, we did actually have a few quarrels over the problem statements, but it was worthwhile.
2. Finding solutions to solve problem statements(how to tackle them)
- Although we had already taken great effort to define the problem statements already, it was even tougher to decide on the solutions to them. We literally used up our whole weekend to only research and brainstorm on the solutions, and honestly we had to sacrifice our other commitments sometimes.
-- What difficulties did you face during the PB solving process and how did you go about solving them?
· Lack of time
All 3 of us had a huge workload and different tests on different days, so we could not really finish our assigned task on time, affecting the group as a whole. We all have different ccas, so it was quite hard to find time during schooldays, and during weekends we have family commitments, religious activities such as attending church etc, so we were unable to find much time.
· Brainstorming
This was the most difficult and strenuous task for us. It could take us more than days to define problem statements and solving them could literally take weeks.
· Researching
On the net, we realised that not all information is reliable and precise. Sometimes, we have people posting information which contradicts another source, and it was an ordeal we had to overcome.
-- What further improvements could have been made?
· Manage time wisely
We have to effectively plan out and come out with our schedule in order to meet each other regularly and consistently. During the start of the term, we had improper coordination, but over the weeks, we had adjusted and were accustomed to the meetings. Sometimes, we have to prepare for last minute tasks.
· Get to know each other more (esp. schedules)
The problem was that we did not have a clear idea on the commitments each of us had, so it took quite some time to come out with a plan for the group. And the fact that we came from different classes made it more difficult at the beginning of the term as we had no clue of each other’s time.
· Sacrifice oneself even at the last minute
Sometimes, if our project was not very good or some errors were last minute discovered, we would have to meet at the last minute (including timings like midnight) so that we could do our project properly.
· Communication
Also, with our busy schedules, it was inevitable to be unable to contact each other at important points of time, such as the afternoon before the deadline, so this caused a coordination problem within the group and some of us ended up doing more than the other at some point of time. Also, at the beginning of the year, when one person tells the second person something and needs him to spread it to the third member, the second person might forget about it and this affects the group as a whole.

Daniel:
I have learnt how to apply the concepts on sound and waves into this project, instead of just studying them and using their formulas in calculations and problem solving. I have also learnt how to manage my time and how to prioritize my time while doing a project, and also learnt how to communicate with the public in conjunction of gathering data and groundwork for this project.

This project has made me consider all factors of a decision and action before implementing it fully, and that I have also developed a more cautious attitude towards the dealing of details and how each small change can affect the whole experiment and structure.

There were many concepts regarding the diffraction and reflection of sound waves that I were unsure of and did not know of at the start of the project, and there was actually too little time for the group to do proper research. I tried to self-study with my teammates during our meet ups, and I managed to render help from a friend’s father, who is a researcher in sound and wave particles, to facilitate the progress of this project.

I feel that we could have factored in more precise measurements and drawn up a much more detailed blueprint for the room, and that as a team all the members must be able to gauge their time usage so as to ensure that the project will not remain stagnant in the long run.

Another trip

Venue: Funan Centre

Brief Description:

We went down to Funan Centre to ask a salesman about how the position of the stereo affects the sound produced. However, he told us that it not just depends on the position of the stereo, but the position person as well.

What we learned:

The salesman told us that from experience, people who use stereos, prefer to put them right in front of themselves, reason being that it produces a much louder sound compared to putting it further at the corner of them room, and that both ears can equally hear the sound produced.
He gave us 2 simple scenarios of how we should customize the position of the stereo. But these are just some basic examples in 2D, because when we asked him about how it affects the sound when the stereos are raised on the wall etc (3D), he said that he wasn’t sure and he told us to ask our physics teacher…lol.

Basically these are the 2 scenarios:


1) Placing the stereo in front of the person

This allows both ears to hear the sound equally and people find this more suitable and popular.


2) Placing the stereo at the corner of the room

This creates more echo as the sound waves hit both walls. This works in the same way as light rays when it reflects against two mirrors.
So that’s all.

RESEARCH DEVELOPMENTS~

For the past few days, we have been doing some research on the positioning of the stereo system and how well it affects the audibility range and sharpness of the sound in all.

First up, we went to Jurong Point shopping mall and walked through the different music and cd stores, with the exception being Courts, to ask them and see how they position their stereo systems. We found out that in most cd stores, such as Gramophone, place their stereo systems at one corner of the room, at the innermost position, and this method of positioning the systems provided clear and loud soundwaves for any kind of music played. On the other hand, the salesman at Courts told me that the positioning of the stereo systems are usually up to the owners, but they recommend thatthe systems are to be placed at the spot where it is further away from the target point, as the stereo speakers can generally generate a large amount of soundwaves which will deflect off the surfaces of the room, without too much compromise on the sound quality. However, I was unable to get an answer when I questioned him on whether the circumstances are different for rooms in other shapes. Lol so much for professionalism...

Anyway, from this short research conducted at Jurong Point, I feel that there can be many various alternatives and methods to placing the stereo systems, but the shape and the placing r of furniture in the room is also equally important, if not more, as they will determine how the sound waves will get deflected and thus produce the maximum range of audibility, which helps us to hear the music from a further distance. We will be doing further research adn we hope to be able to go to busier shopping districts such as Suntec, Orchard etc to look for more of these kind of stores for a wider range of interviews and comments. JIAYOU XD