The frequency and wavelength of sound waves

The frequencies of sound that the average human ear can perceive range from a low of around 20 Hz to a high of around 20,000 Hz. Most of the information contained in the human voice, however, is limited to the range between about 100 and 2,000 Hz. The physical range of frequencies of sound is much greater than what humans can hear. Whales can sense sounds in water at frequencies below 10 Hz. Bats can sense sound frequencies in air higher than 100,000 Hz. Read the text aloud Show There is no sound in space
Frequencies of sound and the average range of hearing
Ultrasound of a fetusMedical ultrasound technology uses sound waves at frequencies of 106 Hz and higher. These frequencies are inaudible to the ear but pass readily through living tissue. Differences in tissue density reflect ultrasound waves back to a detector and allow sophisticated imaging without harm to the patient. The figure on the right is an ultrasound image of a 22-week old baby still in the womb. Read the text aloud
Speed of sound wavesThe wavelength of sound in air is comparable to the size of everyday objects. For example, a 1,000 Hz sound wave in air has a wavelength of 34 cm, or about the length of your forearm. The wavelength of sound is important in many technologies, including musical instruments. To design a vibrating object to make a certain frequency of sound, the size of the object must be comparable to the corresponding wavelength of the sound. A trombone is a good example. Pulling in the slide on a trombone results in a shorter wavelength vibration and a higher frequency sound. Read the text aloud
The wavelength of sound varies depending on the properties of the material through which the sound is traveling. A 1 kHz (1,000 Hz) sound in air at 20ºC and 1 atmosphere has a wavelength of 34 cm. A 1 kHz sound wave in water has a wavelength of 150 cm, almost five times longer than in air. In general, the more resistant to compression a medium is, the longer the wavelength for a given frequency of sound. Steel is even more resistant to being compressed than water and the wavelength of a 1 kHz sound in steel is 5 m! Read the text aloud Show Does temperature have an effect on wavelength?
Sound waves of a frequency of 172 Hz have a wavelength of 2 m in air. When these waves enter water, their wavelengths change to 8.7 m. What is the speed of sound in water?
  1. 19.7 m/s
  2. 39.4 m/s
  3. 343 m/s
  4. 1,496 m/s
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Why are many representations of sound waves, such as the waveform graph, misleading? Show

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