18 terms

CH 21

Distinguish between noise and music.
Noise corresponds to irregular vibrations of the eardrum produced by some irregular vibrations in surroundings, while the music contains periodic tones or musical notes.
What are the three principal characteristics of musical tones?
Pitch, Loudness, and Quality.
How does high pitch musical note compare with a low one in terms of frequency?
A high pitch musical note has a higher frequency but less than 4 kHz than a low pitch musical tone.
How does the highest pitch one can hear vary with age?
As the person grows older, high pitch sound becomes inaudible. As a result, an old person can't hear high pitch music that a younger person can hear.
What is a decibel, and how many decibels correspond to the lowest intensity sound we can hear?
A sound of 10 decibels is 10 times as intense as 0 decibels. Decibels are a measure of loudness. And corresponding to the lowest intensity sound.
Is the sound of 10 dB 30 times greater than the threshold of hearing, or 103 (a thousand) times greater?
〖10〗^3 one thousand times greater than the threshold of hearing.
Distinguish between sound intensity and loudness.
Sound intensity is purely objective and the physical attribute of a sound wave depends on the amplitude of pressure variations within the sound wave. In contrast to this, loudness is a physiological sensation of the war, with some frequencies sounding much better than others.
How does the loudest sounds we can tolerate compare with the faintest sounds?
The loudest sound that we can tolerate is almost one trillion times more intense than the finest sound we can hear.
What is it that determines the pitch of a note?
The lowest frequency, called the fundamental frequency of the instrument, determines the pitch of the note.
If the fundamental frequency of a note is 200 Hz, what is the frequency of the second harmonic? The third harmonic?
Pitch = 200Hz therefore Frequency if the second harmonic = 2x200=400 Hz. Frequency of the third harmonic =3x200=600 Hz.
What exactly determines the musical quality of a note?
The number and relative loudness of the partial tones determine the quality of the sound.
Why do the same notes plucked on a banjo and on a guitar have distinctly different sounds?
At the same frequency, they produce different partials. So we hear very distinct sounds from the banjo and guitar.
What are the three principal classes of musical instruments?
1. Stringed instruments: sound is produces by vibrating strings. 2. Wind instruments: sound is produced by vibrating air columns. 3. Percussion instruments: sound is produced when a two- dimensional membrane or elastic surface is struck.
Why do orchestras generally have a greater number of stringed instruments than wind instruments?
The vibration of the string is transferred to the air/ surroundings with low efficiency. To compensate for this, a greater number of string instruments are played compared to wind instruments.
What did Fourier discover about complex periodic wave pattern?
Fourier discovered that all complex periodic wave patterns can be disassembled into simple sine waves that add together.
A high-fidelity sound system may have a frequency range that extends up to or beyond 20,000 Hz. What is the purpose of this extended range?
To exactly duplicate the music of a piano composition , the sound systems must have frequencies up to 20,000 Hz. The greater the electrical sound system's range of the frequencies, the closer the musical output approximates the original sound. Thus, the high fidelity sound system has a wide range of frequencies.
How was the sound signal captured on photograph records of the 20th Century? How is the sound signal captured on a CD?
The phonograph records utilized a conventional stylus(niddle) that vibrated in the grove of a disc. The vibration produced by the groove then transformed to an electrical signal. In CDs the sound signal is stored in digital form. There are billions of pits in CDs and when a laser beam is directed into the CD, "on" and "off" pulses correspond to the 1 and 0 if the digital signal.
Why does the use of blue light allow more information on a DVD?
The pits that are imbedded in DVDs are of two types short and long. A laser beam reads these pits. When the beam falls on a short pit on the reflective surface, it is reflected directly into the player's optical system and registers at 0. When the beam is incident upon a long pit the optical system register a 1. DVD discs have smaller pits which make the length of spiral track more than twice as long as that of a CD. The smaller pits of DVD are read with laser light of shorter wavelength. Hence shorter wavelengths blue lights reads more information stored on a DVD.