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  • 声音的强度和声音的大声

    Two friends whispering close to each other, illustrating varying sound intensity.

    A friend whispers to you in a voice so soft that she has to lean very close so you can hear what she’s saying. Later that day, your friend shouts to you from across the gymnasium. Now her voice is loud enough for you to hear her clearly even though she’s several meters away. Obviously, sounds can vary in loudness.
    ::一位朋友用非常柔软的声音低语你,以至于她必须靠近一点,以便你听到她说的话。 当天晚些时候,你的朋友从体育馆对面向你喊叫。 现在,她的声音足够大声,即使她离她几米远,你也能清楚地听到她的声音。 显然,声音在响亮时会有所不同。

    It’s All About Energy
    ::能源全是关于能源的

    Loudness refers to how loud or soft a sound seems to a listener. The loudness of sound is determined, in turn, by the intensity of the . Intensity is a measure of the amount of in sound waves. The unit of intensity is the decibel (dB) .
    ::响声是指声音对听众的响声或软声。声音的响声又取决于声音的强度。强度是音波量的量度。强度的单位是分贝(dB) 。

    Decibel Levels
    ::Decibel 级别

    The Figure shows decibel levels of several different sounds. As decibel levels get higher, sound waves have greater intensity and sounds are louder. For every 10-decibel increase in the intensity of sound, loudness is 10 times greater. Therefore, a 30-decibel “quiet” room is 10 times louder than a 20-decibel whisper, and a 40-decibel light rainfall is 100 times louder than the whisper. High-decibel sounds are dangerous. They can damage the ears and cause loss of hearing.
    ::图中显示不同声音的分贝水平。 随着分贝水平的提高,声波的强度更大,声音也更大。 每10分贝的音响强度增加10倍,响声是10倍。因此,30分贝的“秘密”房间比20分贝耳语高10倍,40分贝的轻降雨量比耳语高100倍。高分贝的声音很危险,可以破坏耳朵,导致听力丧失。

    A bar graph displaying decibel levels of various sounds, indicating intensity and loudness.

    Q: How much louder than a 20-decibel whisper is the 60-decibel sound of a vacuum cleaner?
    ::问:吸尘器的60度耳语声比20度耳语还响多少?

    A: The vacuum cleaner is 10,000 times louder than the whisper!
    ::A:吸尘器比耳语高一万倍!

    Amplitude and Distance
    ::振幅和距离

    The intensity of sound waves determines the loudness of sounds, but what determines intensity? Intensity results from two factors: the amplitude of the sound waves and how far they have traveled from the source of the sound.
    ::声波的强度决定着声音的响亮度,但什么决定着强度?强度来自两个因素:声波的振幅以及声波从声音源头走多远。

    • Amplitude is a measure of the size of sound waves. It depends on the amount of energy that started the waves. Greater amplitude waves have more energy and greater intensity, so they sound louder. 
      ::振幅是测量声波大小的尺度。它取决于引发波浪的能量量。更大的振幅波的能量和强度更大,因此声音更响亮。
    • As sound waves travel farther from their source, the more spread out their energy becomes. You can see how this works in the Figure . As from the sound source increases, the area covered by the sound waves increases. The same amount of energy is spread over a greater area, so the intensity and loudness of the sound is less. This explains why even loud sounds fade away as you move farther from the source.
      ::当声波远离其源头时, 它们的能量就会越发分散。 您可以在图中看到它是如何工作的。 从声源增加, 声波覆盖的区域会增加。 同样的能量在更大的区域中扩散, 因此声音的强度和声响会越小。 这就解释了为什么在声音越远离源头时声音越大,声音就越小。
    Sound Waves Spreading Out In Areas As Distance From The Source Increases.
    This diagram represents just a small section of the total area of sound waves spreading out from a source. Sound waves actually travel away from the source in all directions.

    Q: Why can low-amplitude sounds like whispers be heard only over short distances?
    ::问:为什么低调听起来像耳语,

    A: The sound waves already have so little energy that spreading them out over a wider area quickly reduces their intensity below the level of hearing.
    ::A:声波的能量已经太少了,因此将声波散布到更广泛的地区,很快会降低听力水平以下的强度。

    The spectrum of sound varies  for different , which is why they all sound different playing the same musical note. Observe the Amplitude vs Frequency graph, known as the Fourier Transform, on the top right graph in the Pan Flute simulation below to learn more:
    ::声音的频谱因不同而不同, 这就是为什么他们的声音都不同, 播放同样的音符。 在下面的泛笛模拟中, 在右上方的图中, 可以看到幅幅与频率图, 称为 Fourier 变形 , 以学习更多 :

     

     

    Further Reading
    ::继续阅读

    Summary
    ::摘要

    • Loudness refers to how loud or soft a sound seems to a listener. The loudness of sound is determined, in turn, by the intensity, or amount of energy, in sound waves. The unit of intensity is the decibel (dB).
      ::声音的响度是指听力者对声音的响度或软度。声音的响度取决于声波的强度或能量量。 强度的单位是分贝( dB ) 。
    • As decibel levels get higher, sound waves have greater intensity and sounds are louder. For every 10-decibel increase in the intensity of sound, loudness is 10 times greater.
      ::随着音频水平的升高,声波的强度更大,声音也更响亮。 每10度音响强度增加10度,声响就会增加10倍。 如果音响强度增加10度,声响就会增加10倍。
    • Intensity of sound results from two factors: the amplitude of the sound waves and how far they have traveled from the source of the sound.
      ::声音的强度来自两个因素:声波的振幅和声波从声源的距离有多远。

    Review
    ::回顾

    1. Define loudness and intensity of sound. How are the two concepts related?
      ::界定声音的响亮度和强度。 这两个概念如何相关?
    2. What is the unit of intensity of sound?
      ::声音的强度单位是什么?
    3. At what decibel level do sounds start to become harmful to the ears and hearing?
      ::听觉和听觉会变得有害吗?
    4. Relate amplitude and distance to the intensity and loudness of sound.
      ::音量和距离与声音的强度和响亮度相对应。