Chapter 26, Problem 43A

A special device transmits out-of-phase sound to a jackhammer operator through earphones. Over the noise of the jackhammer, the operator can easily hear your voice while you are unable to hear his. Explain.

To determine

To explain that over the noise of jackhammer, the operator can easily hear your voice while you are not able to hear his when a special device transmits out-of-phase sound to jackhammer operator through earphones.

Answer to Problem 43A

Jackhammer can hear your voice while you are not able to hear his because the special device decrease the jackhammer noise using transmitting out-of-phase sound which leads to occurrence of destructive interference which decrease the amplitude by cancelling the noisy sound.

Explanation of Solution

Introduction:

When the crests of one wave overlaps with crests of another wave, then there is constructive interference between two waves and there is increase in amplitude.

When the crests of one wave overlaps with troughs of another wave, then there is destructive interference between two waves and there is decrease in amplitude.

These special devices cancel the sound of jackhammer using principle of interference. Hence, Jackhammer can hear your voice while you are not able to hear his because the special device decrease the jackhammer noise using transmitting out-of-phase sound which leads to occurrence of destructive interference which decrease the amplitude by cancelling the noisy sound.

Conclusion:

Thus, Jackhammer can hear your voice while you are not able to hear his because the special device decrease the jackhammer noise using transmitting out-of-phase sound which leads to occurrence of destructive interference which decrease the amplitude by cancelling the noisy sound.