Fast and Easy Science Fair Projects: Singin' in the Shower

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Tape MeasureCassette tape (or) CD player
Tape Measure
Tape Measure
Cassette tape (or) CD player
Cassette tape (or) CD player

Acoustics: the behavior of confined sound

Purpose: To find out if different rooms in your house have different acoustics (sound qualities).

Overview: A branch of physics that studies the physics of sound is called "acoustics." You often hear the word acoustics when someone is talking abour the characteristics od sound in a particular place. Smooth, hard surfaces reflect sound waves off the object. Hardwood floors, walls, and glass are examples of things that reflect sound. Other materials absord (soak up) sound waves instead of reflecting them, or do not reflect all of the sound that strikes them. These include carpenting, curtains, and couches.

     When sound reflects off objects, it can create either an echo or a reverberation. An echo is a distinct repeat of a sound. When sound bounces off an object far away, an echo is often heard, such as shouting into a high cliff. The farther away the reflecting object is, the longer will be the delay between a shout and the echo. A short echo may be heard if you stand far back from the side of a brick building, such as your school might have, face the large brick or concrete wall, and give a sharp yell.

     The term reverberation, or simply reverb, is used to describe the sound of thousands rather than seperate distinguishable sounds. It is caused by sound bouncing many times off different objects. You will hear a reverb effect if you talk in an empty room that has bare walls and floor. Some sound will bounce only once before reaching your ear, while other sound may bounce from wall to wall two, three, or several times before they reach your ear.

     Reverberation and echoes can make listening difficult when a person is speaking, as a lecturer in a large hall or a pastor in a church would do; but a little reverb can make some kinds of music sound more interesting giving them a fuller sound.

     Rooms in libraries and hospitals are places where architects and builders try to reduce the reverberation of sound so as to keep the rooms quieter. Theaters are designed to keep sound from bouncing around, so that a person speaking on stage can be more easily heard and understood.

     Where you live, the room that probably reflects sound the most is the bathroom and in that room, the shower is the most reverberant. Have you noticed that effect?

Hypothesis: A sound recording made in a bathroom, which has a lot of effective surfaces, will sound different from a recording mafe in a room with heavily furnished and carpeted.

You need:

  • portable battery-operated cassette tape or CD player
  • portable battery-operated cassette tape recorder with built-in microphone
  • blank casssette tape
  • tape or CD with your favorite song in it
  • bathroom that is not carpeted or an uncarpeted kitchen or long empty hall
  • a room with carpenting, window drapes, and unholstered furniture or cloth material (such as a couch or bed)
  • tape measure

Procedure: Place a battery-operated tape recorder on the floor of a bathroom, a kitchen, or any room that does not have a carpet and unholstered furniture. Place a battery-operated tape or CD player on the floor of the same room at a distance of six feet or more. Put a blank tape in the recorder. Put a music tape or CD containing your favorite song in the player. Start recording on the tape recorder, and play the song on the other player. Let the recorder and player run for about one minute. Stop them both. If you are using music tape, rewind it back to the beginning.

     Set up the two machines in another room, one that is carpeted, has drapes on the windows, and has a bed with covers or has upholstered furniture, as you would find in a living room. Place the tape machines at the same distance from each other. The song, the tape machines, and the distance apart are kept Constant. The Variable is the environment the recorders are in. Again, start recording on the one machine and play the song on the other. After one minute, stop the tapes and rewind both of them.

     Listen to the recording you made. Compare the "acoustics" or sound qualities of each recording. Write down a description of both rooms and the things that are contained in them.

Results & Conclusion: Write down the results of your experiment. Come to a conclusion as to whether or not your hypothesis was correct.

Something more: 1. Lift the lid of a washing machine and give a yell, then kneel in front of the couch and yell; descibe the difference in the two sounds.

2. Compare a recording made inside the house and one made outside.


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