Which Can Be Heard Better

Classical Mechanics Level 2

Two people are playing their respective drums with the same strength: a small side drum and a big low drum. The wave fronts generated by the two drums are as shown above. Which of the two drum sounds can be heard better by Calvin who is around the corner?

The sound of the side drum The sound of the low drum There's no saying. Nothing can be beard.

7 solutions

Ravi Kumar Varma
Mar 21, 2014

the waves with higher wavelenth bends more easily across corners. for example light has very low wavelength, so they bend very little across corners. Here the wavelength of low drum sound is higher than side drum. so, it bends more and reaches calvin more easily

This can be slightly deceiving, as low instruments, such as the double bass, have their lower registers in the sub-bass range, which is hard for our ears to hear. As a result, the double bass sounds much quieter than one might expect from it's size.

Albert Xu - 7 years, 2 months ago

The low drum has a lower pitch than the side drum, therefore, Calvin hear the lower pitch drum clearly than that of the higher pitch side drum.

lok Cheung - 7 years, 2 months ago

why IS the wave length of red color higher THAN that of blue color?????

ramzan ali - 7 years, 2 months ago

The Red lines are farther apart from one another as compared to blue lines. this suggests they have higher wavelength. The name Lower drum means it has lower frequency. As (frequency = wave speed / wavelength), so frequency and wavelength are inversely related. this is another reason for red lines to have higher wavelength.

Sajid Ali - 7 years, 2 months ago

thanks for your explanation Great!

mahgrine rasika - 7 years, 2 months ago

nice only for short distances

Krishna Gudi - 7 years, 2 months ago

does the hearing of sound by calvin depend upon frequency?????

Ansari Bushra - 7 years, 2 months ago

Yes... U can say hearing of sound directly proportional to wavelength or inversely proportional to frequency

TASSO TADI - 7 years, 2 months ago

Yes....ears have non linear or logarithmic response

Simran Arora - 7 years, 2 months ago

no.. it depends on wavelength......

Poorva Patel - 7 years, 2 months ago

The sound produced by bigger drum, because of its large surface area.....

Shahzaib Minhas - 7 years, 2 months ago

nothing

pradeep Shan - 7 years, 2 months ago

Is this phenomenon diffraction??

Tejas Rangnekar - 7 years, 1 month ago

Sushant Verma
Mar 29, 2014

The sound of low drum is heard than the sound of the side drum by calvin.because the wavelenth of sound of low drum is comparable to the aperture so it bends more. But by chance if the position of the ear of calvin coincides with the minima of the diffraction of the low drum then calvin will hear no sound from the low drum. But if we take probability then the chances of sound of low drum heard by celvin is more.

Refer boundary effect.

Simran Arora - 7 years, 2 months ago

But if there is a chance that a drum can not be heard, then "There's no saying" would be correct.

Steven Perkins - 4 years, 7 months ago

Iram Udoy
Apr 27, 2014

man has the power of hearing sound of 20hz-2000hz. the lower drum creates higher wavelength than side drums and creates a sound above 20hz. so, the sound of lower drums easily reaches to calvin.

Raksham P
Apr 5, 2014

If we consider both sources to be point sources,since intensity is inversely proportional to square of distance so lower drum will be heard better as it is closer.

Amrita Nayak
Mar 30, 2014

Since the surface area of the larger drum is greater, the amplitude of the sound waves formed when the membrane is hit will be greater that that of the smaller drum. Since greater amplitude means greater amount of energy, a person would hear it better.

Anuj Sharma
Mar 29, 2014

Here... theres a difference in amplitude in low big drum and small drum . Amplitude of low big drum is much higher compared to small drum even both have same intensity . Thus higher/Longer the amplitude, more clearly its heared by our ears. :-)

Shu Huan Cheah
Mar 28, 2014

Besides that the waves from the low drum diffract more than the side drum, the low drum is nearer to the bending corner compared to the side drum, therefore the drop in amplitude of the waves from the low drum at that point should be less than the side drum.

According to the figure, calvin is positioned in a shadow area. He wont be hearing anything.

Deepesh M - 7 years, 2 months ago

Which Can Be Heard Better

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