A Reflection on Anti-Noise Technology in Cars

Is it possible for a car to completely negate any sound from outside?

What would have to be created to cause destructive interference with any sound in the car? Do you believe the manufacturers claim is correct?

Answer:

I guess you mean that any sound coming from outside is negated. First, this would mean that you cannot hear some signals that may help you to avoid accidents, so you do not want this technology.

Now, let's evaluate the possibility of completely negating sound in a car. Suppose you have a sound wave approaching the car, the car would need to cancel the sound waves as they approach the surface. In order to achieve this, another wave with equal amplitude but with a phase change of pi would need to be created to cause destructive interference with the incoming sound wave.

One issue is the instantaneous creation of the cancelling wave. The car would need to analyze the incoming sound wave and instantly create another wave to cancel it out. Additionally, as sound propagates as spherical waves, complete cancellation would be difficult to achieve as the wavefronts from distant waves would have a larger radius than those produced by the car.

Another approach to isolating the car from external noise is using isolating panels that absorb and transmit minimal sound. However, a significant amount of isolating material would be required to cancel out almost all sound, which would necessitate a large car.

Therefore, based on the principles of sound waves and interference, it is unlikely that a car can completely negate sound from outside. The manufacturer's claim of total sound negation inside the car may not be entirely accurate.