Read the following case and answer the question given below:
During a science activity, a group of students uses a sound-generating app to investigate different characteristics of sound. They begin with a sound of \(100\ Hz\) and gradually increase the frequency while listening carefully to the changes. They also change the amplitude of the sound and observe that some sounds become louder without necessarily becoming higher-pitched.
Later, the students generate a sound of \(25,000\ Hz\). Some students cannot hear this sound, even though the app is working normally. The teacher then demonstrates two musical instruments playing the same note at approximately the same loudness. Although the fundamental frequency of the sounds is the same, the students notice that the instruments still sound different.
Later, the students generate a sound of \(25,000\ Hz\). Some students cannot hear this sound, even though the app is working normally. The teacher then demonstrates two musical instruments playing the same note at approximately the same loudness. Although the fundamental frequency of the sounds is the same, the students notice that the instruments still sound different.
1. When the students increase the frequency of the sound while keeping its amplitude nearly constant, they notice that the sound becomes higher-pitched but does not necessarily become louder.
Why does this happen? Explain the roles of frequency and amplitude in this observation.
Why does this happen? Explain the roles of frequency and amplitude in this observation.
Increasing the frequency means that the source produces , resulting in an increase in the . Pitch depends on the , whereas loudness is mainly associated with the . Therefore, when the frequency is increased while the amplitude remains nearly constant, the sound becomes higher-pitched but does not necessarily become louder.
2. The students generate a sound of \(25,000\ Hz\), but none of them can hear it. One student concludes that the sound is not being produced because the app is faulty.
Do you agree with the student's conclusion? Analyse the situation using the concept of the human audible range.
Do you agree with the student's conclusion? Analyse the situation using the concept of the human audible range.
No, the student's conclusion is incorrect because \(25,000\ Hz\) is of human hearing. The approximate human audible range is . Therefore, the sound can be produced even though the students cannot normally hear it because its frequency lies in the .
3. The students then listen to two musical instruments playing the same note at approximately the same loudness. Although the fundamental frequency is the same, they can still distinguish which instrument produced each sound.
How is this possible? Explain using the concepts of fundamental frequency, overtones and timbre.
How is this possible? Explain using the concepts of fundamental frequency, overtones and timbre.
The students can distinguish the instruments because the sounds can have different . Although both instruments have the same , they may produce different combinations and relative strengths of overtones. These differences give each instrument its , allowing the listener to distinguish between them.