Which one of the following statements is not correct ?
- (a)Pitch of a sound is its characteristic by which we can generally differentiate between a male voice and a female voice
- (b)The loudness of sound is related to its frequency
- (c)A musical sound has certain well defined frequencies which are generally harmonics of a fundamental frequency
- (d)The timbre of a particular musical sound is related to the waveform of the sound wave
Correct — B, the statement that loudness is related to frequency, which is the one that is not correct. Loudness is the sensation produced by the energy the wave carries, and that energy is governed by the amplitude of the vibration, not by how often it repeats. Double the amplitude of a sound wave and you carry four times the intensity, which is heard as a much louder note; change the frequency instead and what changes is the pitch, while the note can stay just as loud. Physically, intensity is proportional to the square of the amplitude, and loudness is measured on the logarithmic decibel scale built on that intensity.
- (a)Pitch of a sound is its characteristic by which we can generally differentiate between a male voice and a female voice — This statement is correct, so it cannot be the answer to a 'not correct' question. Pitch is the perception of frequency, and an adult male voice typically has a lower fundamental frequency than an adult female voice, which is exactly why the two are told apart by ear.
- (c)A musical sound has certain well defined frequencies which are generally harmonics of a fundamental frequency — Also correct. A musical note is periodic, and its overtones are whole-number multiples of a fundamental frequency. It is the absence of this orderly relationship that makes a sound noise rather than music.
- (d)The timbre of a particular musical sound is related to the waveform of the sound wave — Correct as well. Timbre, also called the quality of a sound, is what lets you tell a sitar from a flute playing the same note at the same loudness, and it comes from the relative strengths of the harmonics, which is precisely what fixes the shape of the waveform.
A musical sound has three characteristics, and each one traces back to a different property of the wave. Pitch corresponds to frequency, loudness corresponds to amplitude and the intensity it produces, and quality or timbre corresponds to the waveform, that is to the mix of harmonics riding on the fundamental. Human hearing covers roughly 20 hertz to 20,000 hertz; below that is infrasound and above it is ultrasound.
The reason candidates lose this one is that loudness and pitch both feel like 'how strong the sound is', so the two get mixed. Keep them apart with a concrete test: a tuning fork struck gently and struck hard gives the same note at two loudnesses, which shows loudness tracks amplitude alone. Loudness is not purely physical either — the ear is much less sensitive at the extremes of its range, so a very low or very high note of the same intensity sounds quieter, but that is a property of the ear, not the relationship the option claims.
- Pitch depends on frequency, loudness on amplitude and the resulting intensity, and quality or timbre on the waveform.
- The intensity of a sound wave is proportional to the square of its amplitude; loudness is measured in decibels on a logarithmic scale.
- In a musical note the overtones are whole-number multiples of the fundamental frequency and are called harmonics.
- The audible range for humans is about 20 Hz to 20 kHz; below is infrasound and above is ultrasound.
- Attaching loudness to frequency — the standard confusion this item is built on.
- Treating timbre as a synonym for pitch; two instruments can share a pitch and still sound completely different.
- Assuming 'not correct' items have only one plausible-sounding option — here three of the four are true statements worth learning in their own right.
Sound characteristics are a recurring GAT item, usually set as a 'which is NOT correct' list, so read every option and identify which wave property each one names.
When the same note is played on a sitar and a flute, the sound produced can be distinguished from each other because of the difference in
- (a) pitch, loudness and quality
- (b) pitch and loudness
- (c) quality only
- (d) loudness only
Answer(c) quality only
The same three characteristics, tested by holding two of them fixed — it isolates timbre exactly as option (d) of the NDA item describes it.
Directions : The following six (6) items consist of two statements, Statement I and Statement II. Examine these two statements carefully and select the correct answer using the code given below. Statement I : The pitch of the sound wave depends upon its frequency. Statement II : The loudness of the sound wave depends upon its amplitude.
- (a) Both the statements are individually true and Statement II is the correct explanation of Statement I
- (b) Both the statements are individually true but Statement II is not the correct explanation of Statement I
- (c) Statement I is true but Statement II is false
- (d) Statement I is false but Statement II is true
Answer(b) Both the statements are individually true but Statement II is not the correct explanation of Statement I
The two facts the present item asks you to keep apart, stated side by side as an assertion-reason pair — pitch with frequency, loudness with amplitude.
- practice — not a real PYQ
The loudness of a sound wave is determined mainly by its
- (a)frequency
- (b)amplitude
- (c)wavelength
- (d)speed
Answer(b) amplitude — intensity, and so loudness, goes as the square of the amplitude, while frequency fixes the pitch instead.
- practice — not a real PYQ
Two sounds of the same pitch and the same loudness produced by different instruments can still be told apart because they differ in
- (a)wavelength
- (b)speed
- (c)quality
- (d)intensity
Answer(c) quality — also called timbre, it comes from the relative strengths of the harmonics and therefore from the shape of the waveform.