Research

Here is research the group found about different materials reflecting sound. We also researched how acoustic sound will bounce back depending on their shape.

Wood- instruments, acoustic guitars

Laminate versus Solid Wood

When reading about acoustic guitars, you may have noticed that cheaper instruments tend to be made of laminated wood, whilst more expensive guitars tend to be made from solid wood.

In a nutshell, an all-laminated body guitar, the top, back and sides will be made from layered (laminated) pieces of wood, most typically laminated spruce for the top, and laminated mahogany for the back and sides.

Solid wood construction means that the guitar is made from solid sheets of wood. Usually, the top and back of an all-solid construction body will be made by joining two solid sheets each to form the top and back, with the join down the centre-line.

The main advantage of using solid wood is that it is far more resonant, and thus has far better tone than a laminate guitar. In addition, many solid tonewoods (particularly spruce) improves over time as the wood dries out and becomes even more resonant. However, solid wood is far harder to work with, and more expensive, making solid guitars more expensive.

Laminated wood is relatively inexpensive, and cheaper to work with, and so is a sensible option to keep costs down. However, whilst solid body guitars often improve in tonal quality over time, laminated guitars will eventually deteriorate (although this is over quite a period of time – don’t panic!).

Generally, solid construction is better. Guitars are available with solid tops and laminated back and sides, making an economical compromise between price and tone, too.

Spruce

Spruce is the most popular wood used for guitar tops, and recognisable by its pale colour and (usually) understated figuring. The reason for its popularity is because it has a tone that makes it a very good ‘all-rounder’. Sweet, and smooth, but not outrageously bright, yet with enough warmth such that it doesn’t sound thin, Spruce sounds good when combined with just about any other tonewood. In addition, it also has pretty good projection and volume to boot.

Spruce is a common species of wood, adding to its guitar material credentials. Sitka spruce is the most commonly found type, with grain varieties such as ‘bear claw’ adding to the aesthetic appeal. Sitka is characterised by is clear fundamental harmonics.

Engleman spruce is typically from North America, and has a warmer, creamier tone than Sitka. Adirondack is a lesser-used type of Spruce, with a louder and brasher tone.

Cedar

Cedar is probably the second most popular material for guitar tops, and can generally spotted by a colour that tends more towards a red-brown.

When compared to spruce, cedar is lot less dense. This makes it quieter, less bright, with less sustain. The upshot, however, is that Cedar is much warmer, and takes less time to reach its full tonal potential.

As a result, Cedar is a popular choice with finger-style players.

Mahogany

Mahogany is probably the most popular choice of tonewood for guitar backs and sides, though it’s also occasionally used as a top material, too. Mahogany is a dense wood, with a dark finish, and close grain. Tonally, it has far warmer, darker tone than both Cedar and Spruce.

As a material for back and sides, mahogany’s density can add great ‘punch’ and projection, adding warmth, but with definition, and a ‘woody’ character.

The combination of spruce and mahogany and spruce is one of the most popular, because it offers a tone that very balanced, but versatile, lending itself very well to most musical styles.

Maple

Though far less common as a tonewood, Maple nonetheless features on some of the most popular acoustic guitars ever made (the Gibson J-200, for example). One of the hardest and most dense tonewood varieties, maple is famed for its bright tone, and great projection, with excellent note definition.

All maple acoustic guitars, and maple tops are not common, but maple back and sides are more so, often adding greater power and mid-range to a more typical top material.

The dramatic figuring can also add a stunning aesthetic touch to a guitar, too.

Rosewood

As one of the most expensive tonewood varieties, Rosewood has a lot to live up to. However, with its smooth, warm tone, with complex harmonic overtones. Visually, Rosewood is typically a dark, chocolate brown in colour, with a widely banded dark grain, and is generally used as a material for the back and sides of a guitar body.

Combined with a Spruce top, Rosewood provides an incredibly balanced and versatile palette of tones.

Indian Rosewood is one of the most desirable (and expensive) tonewoods, with warm, but singing harmonics. Brazilian Rosewood has a slightly brighter, less complex tone, with a defined low-end.

Metal- instruments like brass

Aluminum

• Sound travels at one of the fastest rates through aluminum, at 6,320 meters per second. This is because aluminum is not particularly dense--meaning that it has little mass in a given volume--and is extremely elastic and capable of changing shape easily. Note that a material's elasticity tends to fluctuate more than its density and is therefore considered more important for understanding the speed of sound through the given material.

Copper

• The next-fastest speed for sound is 4,600 meters per second in copper. With its elasticity and thus ability to vibrate in place easily, sound travels through quickly. However, it is much more dense than aluminum, which explains why it is nearly two-thirds slower than aluminum.

Plastics-

Plastic
material    Velocity long.
meter/sec    Density
g/qcm    Acoustic Impedance
Attenuation
dB/cm, 5MHz or []
ABS, beige    2230    1.03    2.31    11.1
ABS, black    2250    1.05    2.36    10.9
ABS, grey    2170    1.07    2.32    11.3
Acrylic, clear    2750    1.19    3.26    6.4
Acrylic,M1-7    2610    1.18    3.08    12.4
Bakelit    1590    1.40    3.63    -
CelluloseButyrate    2140    1.19    2.56    21.9
Delrin, black    2430    1.42    3.45    30.3
Ethyl vinil acetat 18% Acet.    1800    0.94    1.69    -
Ethyl vinil acetat 28% Acet.    1680    0.95    1.60    -
PVC Acrylic Alloy Sheet    2218    1.35    2.99    -
Polycarbonat Lexan    2300    1.20    2.75    23.2
Lustran, SAN    2510    1.06    2.68    5.1
Mylar    2540    1.18    3.00    -
Kodar PETG Copolyester    2340    1.27    2.97    20.0
Melopas    2900    1.70    4.93    7.2 [2.5]
Nylon, 6/6    2600    1.12    2.90    2.9
Nylon, black, 6/6    2770    1.14    3.15    16.0
Polycarbonate, black    2270    1.22    2.77    22.1
Polycarbonate, blue    2260    1.20    2.72    23.5
Polycarbonate, clear    2270    1.18    2.69    24.9
Polyethylene    1950    0.90    1.73    -
Polyethylene, high density    2430    0.96    2.33    -
Polyethylene, low density    1950    0.92    1.79    2.4
Polyethylene oxide    2250    1.21    2.72    -
Polypropylene, Profax    2740    0.88    2.40    5.1
Polypropylene, white    2660    0.89    2.36    18.2
Polystrene "Fostarene 50"    2450    1.04    -    -
Polystrene "Lustrex"    2320    1.04    2.42    3.6
Polystrene, Styron 666    2400    1.05    2.52    1.8
Polyvinyl butyral    2350    1.11    2.60    -
PSO, Polysulfone    2240    1.24    2.78    4.25 [2]
PVC, grey    2380    1.38    3.27    11.2
Styrene Butadiene    1920    1.02    1.95    24.3
Dimethyl pentene Polymer    2200    0.83    1.84    3.8[1.3]4.4[4]
Valox, black, glass filled Nylon    2530    1.52    3.83    15.7
Vinyl, Rigid    2230    1.33    2.96    12.8

Wood- good for instruments

Metal- aluminum and copper best for speed of sound

Plastic- about half the speed of metals

To make this product more effective to have a home theater kind of function the use of acoustic sound would be most cost effective and that certain style that people will enjoy. When sound hits something such as a wall, the energy or the sound will bounce off of the wall and go through it or be absorbed by it. The sound mostly comes back off the wall because that is the easiest way for the energy to go rather than having to work it’s way through the surface. A surface that is concave will produce a more focused reflected sound.

This is because the sound waves hit the concave surface, the angle will bounce the waves back inward and concentrate the sound to a specific point. If the surface were flat, the sound would bounce back and continue to expand outward and the sound would dissipate. If the surface were convex, it would further push the sound waves outward, creating even less of a concentrated sound, which would be noticeably quieter to the ear, and it would not be as crisp.