Experiment

Introduction

I am a cello student. I decided to investigate whether I am exposed to average or peak sound levels which are damaging to my ears. The Workers' Compensation Board in British Columbia sets limits on the amount of sound a worker can be exposed to in a 24 hour period. For example, a worker cannot be exposed to an average sound level of more than 85 decibels for 8 hours a day. The maximum allowable instantaneous sound level is 140 decibels. (Please see the entire chart in "Interesting Facts".)

Hypothesis

The sound levels I am exposed to while playing the cello are high enough to cause damage to my hearing.

Materials

Lawson Davis Sound Level Meter and calibrator

Method

I tested the sound levels in various situations in which I play. For example, I tested the sound levels when I was practising a piece in my bedroom, when I was playing the same piece in the cello studio where I take lessons, with my teacher accompanying me on the piano and when I played that piece in the living room of a violinist's house. I also tested sound levels when I was playing a duet with the violinist in her living room, when I was playing a trio with her and her violin teacher in the teacher's studio and when I was playing in a 21 person cello orchestra in a church. I also compared the sound levels reaching my ears with the sound levels which were reaching the ears of the violinist while we were playing the duet together.

I used a hand-held Lawson Davis Sound Level Meter. It measures sound in decibels. The intensity of sound doubles with each increase of three decibels. With each increase of ten decibels, the intensity of sound increases by ten times. My mother helped me record the sound levels while I played the cello. The sound level meter was held about seven centimeters away from the opening to the ear canal in the right and left ears.

Results

`Sound Level Data `
`  `
`Practice–Solo Cello `
`Location: my bedroom–hardwood floors, small area rug, small room with lots of furniture`
`Piece: Danse Rustique Op.20, No.5, W.H. Squire`
`Sound Level Readings (Decibels)`
```Average Levels-Left Ear-81.1, Right Ear-80.8

```
`Peak Levels-Left Ear-105.8, Right Ear-105.7`
```

Practice–Solo Cello```
`Location: living room at violinist’s house–carpeted, large number of windows, heavy draperies, lots of soft, upholstered furniture, very high ceilings.`
`Piece: Danse Rustique Op.20, No.5, W.H. Squire`
`Sound Level Readings (Decibels)`
`Average Levels-Left Ear-80.9, Right Ear-79.1`
`Peak Levels-Left Ear-101.9, Right Ear-101.6`
```

Cello Lesson–Cello and Piano```
`Location: Cello studio–carpet on floor, large windows behind cello student’s chair, quite a lot of furniture.`
`Piece: Danse Rustique Op.20, No.5, W.H. Squire`
`Sound Level Readings (Decibels)`
`Average Levels-Left Ear-81.8, Right Ear-82.4`
```Peak Levels-Left Ear-108.1, Right Ear-103.2

Violin–Cello Duet: played here as a trio with two violins and one cello.```
`Location: Violin studio–large glass windows, wood ceiling, wood furniture, laminate floor.`
`Piece: Bourrée from English Suite 1, J.S. Bach`
`Sound Level Readings (Decibels)`
`Average Levels-Left Ear-85.3, Right Ear-86.6`
`Peak Levels-Left Ear-105.6, Right Ear-107.3`
```

Violin–cello Duet: played here as a duet with one violin and one cello.```
`Location: living room at violinist’s house–carpeted, large number of windows, heavy draperies, lots of soft, upholstered furniture, very high ceilings.`
`Piece: Bourrée from English Suite 1, J.S. Bach`
`Cello Sound Level Readings (Decibels)`
`Average Levels-Left Ear-81.0, Right Ear-80.9`
`Peak Levels-Left Ear-100.7, Right Ear-101.9`
`Violin Sound Level Readings (Decibels)`
`Average Levels-Left Ear-87.6, Right Ear-84.2`
`Peak Levels-Left Ear-105.7, Right Ear-105.3`
```

Cello Orchestra Rehearsal–21 cellos```
`Location: area where orchestra sitting was carpeted, rest of church half carpet and half hardwood, extremely high ceilings.`
`Piece: 76 Trombones (from Meredith Wilson’s The Music Man)`
`Sound Level Readings (Decibels)`
`Average Levels-Left Ear-85.4, Right Ear-84.6 `
```Peak Levels-Left Ear-108.5, Right Ear-106.1

```

Conclusions

The numbers recorded on the sound level meter seem to show quite small differences in intensity or loudness of the sound.However it is important to remember that a three decibel increase in sound means that the sound has doubled in intensity.

The sound levels measured at my left ear were generally higher than the levels measured at my right ear. Maybe this is because the cello is held toward the left side of my body. Possibly my right arm, which is my bowing arm, interferes with sound waves on the right side of my body causing less sound to reach my right ear. The average and peak readings were higher in my right ear when I was playing in the cello-violin trio. However I believe that was because the violinists were standing close to my right side.

The physical environment seemed to make a difference in the sound level readings. For example, when I played with 20 cellists in the church I thought the sound levels would be much higher than when I played alone or with a small group. They were higher than when I played alone but were quite similar to the sound levels when I played in the cello-violin trio. This might be because there were extremely high ceilings in the church which allowed the sound to disperse, and carpeting which absorbed sound. Also, I was seated in the front row near the edge of the group. When I played in the trio I was in a small room with very hard surfaces which reflected sound. A similar situation happened when I played my solo piece in my bedroom compared to when I played that piece in the violinist's living room. The sound levels were lower in her living room which also had very high ceilings as well as carpeting and soft draperies.

When I played a cello-violin duet the sound levels reaching my ears were significantly less than the sound levels reaching the violinist's ears. The f-holes of her violin, where the sound escapes from the instrument, were very near her ears, especially her left ear. The f-holes on my cello were much farther away from my ears.

In conclusion, I did not prove my hypothesis which is a good thing! My average sound levels were in the mid-80 decibel range. I play cello approximately 1-1.5 hours a day. The BC Workers' Compensation Board regulations say that I can safely play at this level for 8 hours in a 24 hour period. My peak levels reached 108.5 decibels. The regulations allow up to 140 decibels for maximum peak instantaneous exposure. I had my hearing tested by an audiologist and my friend and I also tested my hearing using an audiometer of his father's. Both tests showed that my hearing is normal. However the audiologist suggested that I wear my musicians ear-plugs when possible when I practice or rehearse in order to be sure to protect my hearing, especially as I plan to significantly increase the amount of time I spend playing the cello over the next year.

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