Chapter 21: Musical Sounds

As we age, our ability to hear high-frequency sounds diminishes. This is due to natural physiological changes in the ear, specifically the deterioration of the hair cells in the inner ear responsible for detecting high-frequency sounds. This gradual decline in hearing sensitivity is known as presbycusis and is a common age-related condition. Therefore, the frequency range of human hearing decreases as we become older.

High pitched sound refers to a sound wave with a high frequency. Frequency is the number of cycles or vibrations per second and determines the pitch of a sound. Therefore, the correct answer is frequency.

The decibel scale is logarithmic, meaning that each increase of 10 decibels represents a tenfold increase in sound intensity. Therefore, a sound of 50 decibels is 10 times more intense than a sound of 40 decibels.

When a note is one octave higher in pitch, it means that its frequency is doubled. In this case, the given note has a frequency of 440 Hz. Doubling this frequency gives us 880 Hz, which is the correct answer.

The pitch of a musical sound refers to how high or low the sound is perceived. It is determined by the frequency of the sound wave. Frequency is the number of complete vibrations or cycles that occur in a second and is measured in hertz (Hz). Higher frequencies result in higher pitched sounds, while lower frequencies result in lower pitched sounds. Therefore, the correct answer is frequency.

As we age, our ability to hear high frequencies gradually declines. This is known as presbycusis, a common type of hearing loss that affects many older adults. High-frequency sounds, such as the chirping of birds or the ringing of a phone, become harder to perceive. This occurs due to the natural aging process, which causes the hair cells in the inner ear to become damaged or die over time. Consequently, older individuals may struggle to hear high-pitched sounds and may require hearing aids or other assistive devices to compensate for this loss.

According to the question, all other things are the same. In the context of strings, the frequency of a note depends on the mass of the string. When a string has more mass, it vibrates slower, resulting in a lower frequency note. Therefore, strings having more mass than other strings will produce lower frequency notes.

The quality of a musical note refers to its distinct characteristics that differentiate it from other notes. Loudness, frequency, and amplitude are all factors that contribute to the overall sound of a note, but harmonics specifically refer to the additional tones that accompany the fundamental frequency of a note. These harmonics give each note its unique timbre or tone color, making it the correct answer.

Reverberation is the persistence of sound after the sound source has stopped. It occurs when sound waves bounce off surfaces and create multiple reflections. Singing in the shower often results in a noticeable reverberation effect due to the enclosed space and hard surfaces, such as tiles, that reflect sound waves. In contrast, the other options - a small drape-covered room, a large drape-covered room, and the desert - do not provide the same level of reflection and containment of sound, thus reducing the likelihood of experiencing reverberation.

The loudness of a sound refers to its perceived volume or amplitude. Intensity is a measure of the amount of energy that is transferred by a sound wave per unit of area, and it directly affects the loudness of the sound. As the intensity of a sound wave increases, the sound becomes louder. Therefore, the loudness of a sound is most closely related to its intensity.

The fundamental frequency of a violin string is the lowest frequency at which it vibrates. The second harmonic is the next frequency at which the string vibrates, which is twice the frequency of the fundamental frequency. In this case, the fundamental frequency is 440 hertz, so the second harmonic would be 880 hertz.

A decibel is a unit used to measure the loudness of a sound. It indicates the intensity or volume of a sound wave. Frequency refers to the number of cycles of a waveform that occur in a second, while wavelength refers to the distance between two corresponding points on a wave. Speed is the rate at which a sound wave travels through a medium. Therefore, the correct answer is loudness, as a decibel is a measure of how loud a sound is.

Fourier discovered that periodic waves can be represented by the summation of a series of simple sine waves. This is known as the Fourier series. By decomposing a periodic wave into its constituent sine waves, Fourier showed that any periodic waveform can be expressed as a sum of sine waves with different frequencies and amplitudes. This concept revolutionized the field of signal processing and allowed for the analysis and synthesis of complex waveforms using simpler components.

The correct answer is amplitude. The loudness of a musical sound is determined by the amplitude of the sound wave. Amplitude refers to the maximum displacement of particles in the medium through which the sound wave is traveling. A higher amplitude corresponds to a louder sound, while a lower amplitude corresponds to a softer sound. Wavelength, frequency, and speed are all properties of a sound wave, but they do not directly determine the loudness of the sound.

A sound of 60 decibels is 10 times more intense than a sound of 50 decibels. Therefore, it can be inferred that a sound of 60 decibels is 100 times more intense than a sound of 30 decibels.

There are 7 octaves present between 20 hertz and 2560 hertz. An octave is a doubling of frequency, so to find the number of octaves between two frequencies, we can divide the higher frequency by the lower frequency. In this case, 2560 divided by 20 equals 128, which is 2 to the power of 7. Therefore, there are 7 octaves between 20 hertz and 2560 hertz.

Between 100 hertz and 1600 hertz, there are 4 octaves. An octave is a musical interval that spans a frequency ratio of 2:1. Starting from 100 hertz, the next octave would be 200 hertz, then 400 hertz, 800 hertz, and finally 1600 hertz. Therefore, there are 4 octaves between these two frequencies.

The threshold of hearing refers to the minimum sound intensity or level that can be detected by the human ear. It is typically around 0 decibels, which means that none of the given choices (10 decibel, 1 decibel, 0.1 decibel, 0.01 decibel) are correct.