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reflection of sound waves
Transcript of reflection of sound waves
2. Identify the factors that would minimize repeated reflections or reverberations. Materials 2 whole newspaper sheets/cardboards
4 rubber bands or strings
book with smooth surface
cushion or throw pillow
stopwatch/alarm clock (if available) Procedures 1. Roll each newspaper sheet/cardboard to form a tube about 4cm in diameter. Tie a rubber band or string around it. 2. Placed the rolled newspaper sheet/cardboard on the table at an angle to each other. With the two ends of the tubes close but not touching each other, let each opposite end extend out of the table. 3. One member (student A) of the group will listen at one end of a tube while another member (student B) will whisper “drop, drop, drop” (or any other word) continuously at the end of the second tube close by. It is important that the whisper is evenly soft throughout. Or place a stopwatch (if available) in the end of one tube instead of having a student whisper. 4. As a student listens to the whisper of Student B or to the tick of the stopwatch, a third member of the group (student C) holds a book upright at the opposite ends of the tubes. Student C sets the book at equal angles to the tubes. 5.Student A listens closely when the book is set upright at the end of the tubes. 6. Student C removes the book and student A continues to listen closely. 7.Change position so that everyone in the group gets to listen to the whisper or to the tick. 8. Use a pillow in place of a book and repeat steps 4-7. Guide Questions 1.Were you able to hear the sound though there is a book as your barrier? Why? Why not? 2. Compare the sound you have heard with the book and the pillow as the barrier. 3. What kind of materials reflects soundwave? Absorbs soundwave? 4. Auditoriums and concert halls are built so that they have good acoustics. What does this mean? Why are these halls fitted with acoustic ceiling tiles, thick curtains and carpets? Choose the letter of the
correct answer. Multiple choice Evaluation 1. Which of the following will happen when sound reflects off a special surface called a parabola?
a. Sound will bounce out in a straight line no matter where it originally hits.
b. Sound will travel from one focus to the other.
c. Sound will be heard clearly by everyone
d. All of the above will happen. 2. An acoustic engineer might place drapes on the walls of an auditorium in order to __________.
a. increase reverberation time.
b. absorb some echoes.
c. produce special echoes.
d. change the shape of the room. 3. Which of the situations below shows a repeated sound reflection?
a. Shouting in an open area.
b. Singing inside a bathroom.
c. Student talking in front of the classroom.
d. Calling on a phone. 4. In what kind of surface sound can be heard clearly?
a. flat surface
b. irregular surface
c. ellipse surface
d. porous surface 5. Which statement best describes reflection?
a. It is produce by vibrating bodies.
b. It is an energy absorbed or bounced by the objects it hits.
c. It is the traveling of wave from one place to another.
d. It is the spreading of soundwave. depending on the source from where it originates. Assignment 1. Aside from the examples discussed, cite three other situations where reflection of soundwaves can be observed.
2. Explain how refraction of sound happens?
Reference: Physics Textbook p. 378 Reflection of
Soundwaves Reflection of sound waves off of surfaces can lead to one of the two phenomena-an echo and a reverberation.
A reverberation often occurs in a small room/area. it happens when the reflected sound waves reaches the ear in less than 0.1 second. This leads to repeated reflection. On the other hand, echo occurs when a reflected sound wave reaches the ear more than 0.1 seconds after the incident wave was heard. In this case the arrival of the sound wave will be perceived as the second sound rather than the prolonging of the first sound. There will be an echo instead of reverberation. Key answer 1. a
5. b In a 1/2 crosswise answer the following: