PHY103 practice exam PHY103 In class Exam will be Nov 9, 2010, Tuesday, 9:40am B+L407 Rules: You can bring a calculator with you to the Exam. Length: You could take the entire 1 hour and 15 minutes, though I am intending that the exam should be shorter than this. The following is a practice exam that is much longer than the actual one. The actual exam will have questions that are very similar to the ones asked here. Note the real exam will have a similar format. One or two questions from each part of two parts must be answered. Sound files relevant for part II can be found at http://astro.pas.rochester.edu/~aquillen/phy103/Sounds/Workshop1/ Reading material for this class can be found at http://astro.pas.rochester.edu/~aquillen/phy103/Reading/ Lectures for this class can be found at http://astro.pas.rochester.edu/~aquillen/phy103/WWW/lectures.html The accompanying sound files are in the sounds directory http://astro.pas.rochester.edu/~aquillen/phy103/Sounds/ and I have started making a directory for each lecture (and with the same title as the lecture) for protected files: user: phy103, pass: music

I. Discussion Question: (total 30 points) Choose one of the following questions to discuss (in about 1 full page or more)

1) What is the tempered scale? What are its advantages and disadvantages compared to other scales such as that with just intonation or the Pythagorean scale? How do you compute the frequencies of the notes in the tempered scale? Discuss modern extensions to the just intonation scale or how the choice of scale affects design of instruments used by groups playing together or affects the type of music composed for such groups.

2) Many musical instruments, including the voice, have a spectrum of nearly harmonic overtones where the frequency of each overtone is almost exactly an integer multiple of a fundamental tone that sets the note played or sung. Explain why this is true for string and wind instruments. Explain why this is also true for the voice. Even though tonal musical instruments often have nearly harmonic overtones, variations from this rule are important. Mention some examples of exceptions to the rule that musical instrument tones have harmonic spectra.

3) Choose a musical instrument and describe its acoustics. Explain how sounds are produced. Discuss the spectrum and timbre of sounds produced. What variations in playing give musicianship? You could discuss a classical, folk or traditional instrument or an imaginary instrument that you might wish to build.

4) The lowest C on the piano is C1 (32.70Hz) octaves below the highest C which is C8. However as you can see from the image showing a grand piano sound board, the largest string on a grand piano is only about 10 times longer than the smallest string. How many times higher is the frequency of the highest C than the lowest C? How is this large pitch range achieved on the piano? Discuss differences in string tension and string linear density (that is mass per unit length) of piano strings as well as the differences in the lengths. If the tension is similar in all strings how different are the linear densities between the strings playing the lowest notes compared to those playing the highest notes?

Soundboard of a grand piano

It may be convenient to have this table handy

Frequencies of Notes in the Tempered Scale 4th octave Note Frequency

(Hz) C4 261.63 C# (D♭)4 277.18 D4 293.66 D# (E♭)4 311.13 E4 329.63 F4 349.23 F#(G♭)4 369.99 G4 392.00 G#(A♭)4 415.30 A4 440.00 A#(B♭)4 466.16 B4 493.88 To predict the notes in the octave above this multiple the above frequencies by two. To predict the notes in the octave below this, divide the above frequencies by two.

II. Questions on Spectral views of sounds: (30 points) Choose two of the following questions to answer:

1) Consider the following spectrum:

A. Is this sound from a

a) piccolo b) drum c) didgeridoo or d) piano?

Explain your reasons for your choice. Explain why you have eliminated the other choices. B. Approximately what note is played in the above spectrum?

2) Consider the following spectrogram of the raga abhogi with instruments flute, sittar, and tablas

a. Which spectral features correspond to flute and which to the smaller tabla and

which to the larger tabla? b. Approximately what is the highest note played by the flute during the sound

clip shown?

3) Consider the following spectrum and waveform.

Is this sound from a) a piccolo b) a harp c) a drum d) white noise e) a clap Explain your reasons for your choice using both wave form and spectral information. Explain why you have eliminated the other choices.

4) Consider the following spectrograph and waveform.

These represent the sounds of a) a piano playing notes on the major scale moving upward in pitch b) a piano playing notes on the scale moving downward in pitch c) a piccolo playing notes on the scale moving upward in pitch d) a piccolo playing notes on the scale moving downward in pitch Explain your reasons for your choice using both wave form and spectral information. Explain why you have eliminated the other choices.

5) Consider the following spectrograph and waveform.

a) What instrument is probably playing? b) What pitch is sounded approximately (what note?) c) What accounts for the variations in pitch and timber? d) What might cause the pitch variation? e) Why are some of the overtones weaker than others? f) Why is the spectrum nearly harmonic (overtones integer harmonics of one another)?

6) Consider the following spectrograph and waveform.

a) What instrument is playing? b) What accounts for the variation in pitch and overtone strengths? c) Why is a harmonic spectrum seen?

7) Consider the following spectrograph and waveform.

A. What type of instrument is playing? Is the spectrum harmonic? Why not? B. This spectrum is from

a) flute b) bamboo tubes of different lengths that are hit c) a single drum d) harp

C. Is the instrument

a) hit with a mallet b) blown c) played with a bow

8) Consider the following sound shown in waveform view and in spectral view:

A. Is this sound from a

e) piccolo f) drum g) piano h) voice i) copper pipes

Explain your reasons for your choice using both wave form and spectral information. Explain why you have eliminated the other choices. B. Is a harmonic spectrum seen? Why or why not? Is a scale played? If so are the notes going up or down?

9) An open string is plucked on an electric guitar. The spectrogram is shown below. After plucking the open string, the player lightly touches his finger to a specific spot on the string and a `natural harmonic’ is heard.

A. Where on the string did the player put his finger? B. The original note played is an A2. What pitch is heard after the guitar player

touches the string? C. More than one overtone is seen in the spectrum on the right hand side of the

spectrogram. Why are some of the harmonics damped and not others?

10) Consider the spectrogram below

a) Describe what this sound would sound like b) What is the frequency ratio between the lowest and highest note played?

How many octaves does this correspond to? To approximately what interval does this correspond?

c) What type of instrument do you think made this and why? Discuss this in terms of modes of oscillation.

d) Which integer harmonics are the strongest? Why aren’t all integer harmonics as strong?

11) Consider the following spectrum showing a piano that is playing 2 notes at the same time.

a. What interval is played? b. What two notes are played? c. Which overtones belong to which note?

12) The following shows a three people singing, a bass and two sopranos.

A. Mark where when the sopranos start to sing. B. About what note is the lowest one sung? C. Mark where the one of the sopranos has a large vibrato

13) Two notes are sung by a bass singer and the resulting spectrogram is shown below.

What is the interval between the two notes? Explain your answer by matching overtones from one note with those in the other note.