Safe Sound Level Practical
Sound are waves produced by vibrations (OpenLearn, 2017). They can travel through solids, liquids and gases. However, the particles move differently in each of these forms. Sound waves travel fastest in solids, followed by liquids, then lastly gases (Oceanservice n.d). The molecules in solids are the most compacted, enabling sound to travel much faster in solids than in liquids or gases (NDT Resource Centre n.d). Sound waves moving through the air are longitudinal waves as they travel back and forth (cs.toronto, n.d.). In water, sound moves at a faster speed than in the air, a gas. If a living object is within range of the vibrations, the sound can be heard. Particles transport energy to the ears through the medium. The faster the vibrations are, the higher the pitch would be. The basic properties of sound consist of pitch, loudness and tone (Siyavula n.d).
A decibel is a unit used to measure sound level. The number of decibels vary depending on the type of activity occurring. A conversation is approximately 60 decibels, but a rock concert is double that at 120 decibels (HealthLink BC n.d.). A safe sound level is considered to be a maximum of 85 decibels for eight hours a day (HealthLink BC n.d.). After extended exposure to sound levels higher than 85 decibels, hearing loss may result. Any noise above 120 decibels may cause instant damage to the ears. Loud noises are especially harmful to the cochlea, the inner ear, as they damage its cells and membranes (Centers for Disease Control & Prevention n.d.).
The aim of this experiment is to investigate which material can be used to block out noise most effectively.
It is predicted that the blanket, which is the thickest material, will have the lowest decibels. This is predicted because it is assumed that the thicker a material is, the harder it would be for the sound waves to penetrate through.
The independent variable for this practical is the different materials used to wrap the phone. They will be changed every 3 trials. The dependent variable is the decibels measured. It will be measured with the Decibel Meter app. A control variable is the time length of each trial. The time can be kept constant by allowing the phone alarm to play 5 times and then stopping it. One of the other control variables is the app. Throughout the investigation, the same decibel app will be used. Another control variable is the distance between the box and the phone. To ensure that the phone maintains an exact distance from the box every time, the phone will be placed directly against the box.
Materials
- Phone alarm
- Phone with Decibel Meter App
- Blanket
- Cardboard box with lid
- Foam
- Bubble Wrap
DiagramCardboard Box
Phone with alarm
Table
Phone with Decibel Meter App
Foam
Blanket
Bubble Wrap
Procedure
- The phone alarm was recorded in the box without any materials wrapped around it.
- Step 1 was repeated 3 times.
- The phone was wrapped with a material (blanket, foam, bubble wrap) until it was completely enclosed.
- The phone was placed in the box.
- The sound was measured after 5 alarm repetitions.
- The results were recorded.
- Steps 3 – 6 were repeated until all the materials were experimented with.
Safety Precautions
Risk
Hazard
Precaution/Actions Taken
The phone alarm is too loud
- Hearing damage may occur
- Earplugs can be worn to prevent hearing damage
- Turn the phone volume to 70%, which is the average range
- If hearing damage occurs, refer to a doctor
Dropping phone
- The phone may fall and break
- Glass from the phone may shatter and cause injuries
- Hold the phone properly
- Don’t put it on the edge of a table
- If phone drops and glass shatters, do not touch the phone with bare hands. Seek assistance from an adult first.
Table of Decibels Recorded for Materials
Phone in box
Blankets
Foam
Bubble Wrap
Trial 1 (dB)
57
54
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49
50
Trial 2 (dB)
56
54
48
52
Trial 3 (dB)
57
51
47
51
Average
56.7
53
48
51
Graph of Average Results
These results display how the decibel levels were different each time the independent variable was changed. When the phone was placed inside the box without any material encasing it, 56.7 decibels was recorded as the average decibel. With the blanket covering the phone, the average decibel number decreased to 53 decibels. When foam was used, the average reduced even more to 48 decibels. However for bubble wrap, the average increased again to 51 decibels on average.
There weren’t any inconsistencies in the data. Each material was tested three times to increase the accuracy of the results. The results would indicate if a trial was done incorrectly as the other two trials would have a noticeably different result. For the blanket trial, there was a 3-decibel difference. In the entire set of results, this was the biggest difference and it isn’t a big number to be considered an inconsistency.
Based on the set of results from this investigation, foam is the best material for blocking sound. This should have been the case because there were around 7 layers of foam wrapped around the phone which made it very thick. Thus, effectively blocking out more sound than the other materials.
During the investigation, three trials were conducted on each material. When comparing, the number of decibels for each of the trials were very similar to each other. Therefore, this investigation had high precision levels.
The accuracy of this data wasn’t high. Based on research, foam is the best sound-proofing material (Soundproofing Tips n.d). Followed by a blanket, then bubble wrap. Acoustic foam, also referred to as studio foam is ideal for absorbing sound (Soundproofing Tips n.d). Regular foam can also do the same, just not as effectively. A thick and dense blanket is also able to absorb noise and reduce echo. But the air pockets in bubble wrap has little sound reduction (Soundproofing Tips n.d). Like what the research stated, the results from this investigation demonstrate that foam is indeed a very effective material to block out sound. However, the results show that bubble wrap was the second best at reducing sound, not the blanket. This may have been because seven layers of bubble wrap were used to wrap the phone but the blanket had fewer layers. The thicknesses of these two materials weren’t identical, therefore the data collected was inaccurate.
A random error which may have occurred was that the phone measuring the decibels wasn’t placed directly against the box. If the distance between the phone and the box differed each time the results would be inaccurate. This would have affected the final data as the true number of decibels wouldn’t have been recorded if the phone was too far away from the box. If the phone was further away than it should have been, the number of decibels would decrease because of the distance. Another random error which occurred was that the phone with the alarm set wasn’t in the exact same position inside the box every time. This could have also affected the results as the decibels app wouldn’t be able to measure the decibels correctly. Depending on the phone’s position, the number of decibels could increase or decrease.
A suggestion of improvement for the next time this investigation is conducted would be to ensure that the phone with the decibel app is placed directly against the box. By doing this, the distance between the box and phone would stay the same every time. The phone with the alarm should also stay in a corner of the box so that it can always stay in the same position.
In conclusion, the aim of this practical was achieved. The data collected from the investigation as well as research indicates that foam is the best sound-proofing material. The hypothesis was not supported as it was predicted that the blanket would have the lowest decibels. However, it ended up having the highest decibels among the three materials tested.
Bibliography:
- OpenLearn 2017, What is sound?, viewed 21 October 2019, https://www.open.edu/openlearn/science-maths-technology/science/physics-and-astronomy/physics/what-sound
- Cs.toronto n.d., What is sound?, viewed 21 October 2019, http://www.cs.toronto.edu/~gpenn/csc401/soundASR.pdf
- Siyavula n.d., Characteristics Of A Sound Wave, viewed 21 October 2019, https://www.siyavula.com/read/science/grade-10/sound/10-sound-03
- Oceanservice n.d., How far does sound travel in the ocean?, viewed 21 October 2019, https://oceanservice.noaa.gov/facts/sound.html
- NDT Resource Centre n.d., THE SPEED OF SOUND IN OTHER MATERIALS, viewed 21 October 2019, https://www.nde-ed.org/EducationResources/HighSchool/Sound/speedinmaterials.htmhttps://www.nde-ed.org/EducationResources/HighSchool/Sound/speedinmaterials.htm
- HealthLink BC n.d., Harmful Noise Levels, viewed 21 October 2019, https://www.healthlinkbc.ca/health-topics/tf4173
- Centers for Disease Control & Prevention n.d., How does loud noise cause hearing loss?, viewed 21 October 2019, https://www.cdc.gov/nceh/hearing_loss/how_does_loud_noise_cause_hearing_loss.html
- Soundproofing Tips n.d., 15 Best Soundproofing Materials and Products, viewed 25 October 2019, https://www.soundproofingtips.com/soundproofing-materials/
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