18 Hz sine tone, to test your Subwoofer/Speaker/Headphones.Humans can detect sounds in a frequency range from about 18 Hz to 20 kHz. (Human infants can actua...

Some decent headphones or a speaker system capable of deep bass are required to feel this sound. This is a super deep frequency tone that you should "feel" much more than hear. You'll likely have...

交流电使用Hz表示其电压变化的频率。 日常生活中的交流电的频率一般为50赫兹或60赫兹，而无线电技术中涉及的交流电频率一般较大，达到KHz及MHz。 不同国家的电力系统的交流电频率不同，通常为50赫兹或者60赫兹。

Connects cells to communicate with environment. Enhances understanding, tolerance and communication. Energizes immune, respiratory and circulation systems. Creates pure and stable life. Cleans...

2018年12月4日 · The tone is classified at infrasound and at just 18.98Hz it's impossible to hear as it falls just outside of the range that the human ear can pick up. It has been suggested that there is a link between the tone and reports of odd sensations and hauntings.

2016年10月6日 · After some exploration and a quick conversation with the lab’s facilities engineer, Tandy discovered a newly installed fan in the lab was emitting a frequency of 18.98 Hz – a low, rumbly tone that humans can barely hear. Coincidentally, 18.98 is very close to the frequency at which the human eye is thought to vibrate.

It is named after Heinrich Rudolf Hertz (1857–1894), the first person to provide conclusive proof of the existence of electromagnetic waves. For high frequencies, the unit is commonly expressed in multiples: kilohertz (kHz), megahertz (MHz), gigahertz (GHz), terahertz (THz).

人眼的共振频率约为18 Hz，这可以解释为什么说此范围内的声音会产生幻觉或幻影现象。 而次声波可能会引起人类敬畏或恐惧的感觉，所以也有人提出设想：

It is called the "Ghost Frequency" because it is theorized that many "haunted" areas simply produce tones close to 18.9 Hz (through resonance or other natural quirks) and people associate the fear response with a "presence" in the area.

Acoustic – frequency of G −7, the lowest note sung by the singer with the deepest voice in the world, Tim Storms. His vocal cords vibrate 1 time every 5.29 seconds. Acoustic – a frequency known as the Mosquito, which is generally only audible to those under the age of 24.