Question
Headphone earpieces can produce sounds that seem very loud to the listener. However, a person standing a meter away may not even be able to hear those same sounds. Why are these sounds so much quieter a short distance away?
• The wavelengths of the waves are too short to reach a person standing a meter away.
• The amplitude of the waves decreases as the sound spreads out and is absorbed by air.
• The frequency of the sound is too high to travel a full meter through the air.
• Sound waves from headphones do not use air as a medium and travel directly into your ear.
• The wavelengths of the waves are too short to reach a person standing a meter away.
• The amplitude of the waves decreases as the sound spreads out and is absorbed by air.
• The frequency of the sound is too high to travel a full meter through the air.
• Sound waves from headphones do not use air as a medium and travel directly into your ear.
Answers
Answered by
GPT-4o mini
The correct explanation for why sounds produced by headphone earpieces can be very loud to the listener but much quieter a short distance away is:
**The amplitude of the waves decreases as the sound spreads out and is absorbed by air.**
When sound is produced, it emanates from the source and spreads out in all directions. As the sound waves move away from the source, their intensity (which is related to the amplitude of the waves) decreases due to the dispersion of energy over a larger area, as well as absorption by the air and other materials. This results in a significant reduction in loudness for anyone standing a meter away from the sound source, such as headphones.
The other options are incorrect for the following reasons:
- **The wavelengths of the waves are too short to reach a person standing a meter away.** This is not true; sound waves, including those produced by headphones, can travel much farther than a meter regardless of wavelength.
- **The frequency of the sound is too high to travel a full meter through the air.** While higher frequency sounds can be absorbed more readily by the air, they can still travel a meter; it's not the travel distance that is the problem, but rather the amplitude and absorption.
- **Sound waves from headphones do not use air as a medium and travel directly into your ear.** This is incorrect; sound waves do propagate through air and are still subject to the same laws of physics as any other sound wave.
Therefore, the reduction in amplitude as the sound disperses is the key reason.
**The amplitude of the waves decreases as the sound spreads out and is absorbed by air.**
When sound is produced, it emanates from the source and spreads out in all directions. As the sound waves move away from the source, their intensity (which is related to the amplitude of the waves) decreases due to the dispersion of energy over a larger area, as well as absorption by the air and other materials. This results in a significant reduction in loudness for anyone standing a meter away from the sound source, such as headphones.
The other options are incorrect for the following reasons:
- **The wavelengths of the waves are too short to reach a person standing a meter away.** This is not true; sound waves, including those produced by headphones, can travel much farther than a meter regardless of wavelength.
- **The frequency of the sound is too high to travel a full meter through the air.** While higher frequency sounds can be absorbed more readily by the air, they can still travel a meter; it's not the travel distance that is the problem, but rather the amplitude and absorption.
- **Sound waves from headphones do not use air as a medium and travel directly into your ear.** This is incorrect; sound waves do propagate through air and are still subject to the same laws of physics as any other sound wave.
Therefore, the reduction in amplitude as the sound disperses is the key reason.