Sound frequencies are anywhere and everywhere, vibrating and resonating out all the time. The definition of frequency itself is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency, which emphasizes the contrast to spatial frequency and angular frequency. The period is the duration of time of one cycle in a repeating event, so the period is the reciprocal of the frequency. To put it another way, there are an endless range of frequencies both audible and inaudible to the human ear.
Humans can generally hear the range between 20Hz (very low bass) to 20,000Hz ( very high pitch), and with age, this range decreases. Also, with things like volume, over exposure, and generally poor respect for the human auditory system, you will experience a decrease sense of hearing sounds. But the frequency still exists. And we are still subject to them. ALL of them. And that’s what this article is focused on.
” Establishing the effect of sounds with frequencies under about 250 Hz has been harder. Even though they’re above the lower limit of 20 Hz, these low-frequency sounds tend to be either inaudible or barely audible, and people don’t always know when they’re exposed to them.” – says audiology researcher Jeffery Lichtenhan of the Washington University School of Medicine in in St. Louis
Scientific evidence of this is certainly hard to establish. Not only is it still a relatively difficult topic to test, but also we would need to test solely humans to make discoveries.
Animals can hear the bulk of sounds we hear, however each animal typically has either an expanded lower or higher end frequency of hearing.
According to the Working Paper on Infrasound Weapons produced by Hungary for the United Nations in 1978, the frequency that is thought to be most dangerous to humans is between 7 and 8Hz. This is the resonant frequency of flesh and, theoretically, it can rupture internal organs if loud enough. 7hz is also the average frequency of the brain’s alpha rhythms; thus this frequency has been described as dangerous but also relaxing.
Other people says that 1khz and 4khz are regarded as the most dangerous frequency areas to the human ear. The ear amplifies the 4khz area the most (due to evolutionary factors e.g. babies crying) so be careful around that but 1khz is considered to be the most physically damaging frequency to the ear.
Shorter frequencies contain more energy for their amplitude, but don’t travel so well through a medium, largely because the energy tends to be transferred into the medium. Hence the ability to use low-powered ultrasound to visualize areas of the human body.
The military use of infrasound weapons is used to penetrate solid objects, such as armor or bunkers. Bass goes right through things, it’s hard to stop (because it doesn’t transfer its energy easily). High frequencies have less penetration, but more energy for the amplitude. You need a lot of volume to produce damage with bass, 184dB is considered the threshold for nuking mice with sub-bass / sonar.
Photo By: Unknown – Acoustic Hailing Devices (AHD) project intelligible speech out to extended ranges. A number of devices created by various manufacturers are in use throughout the Department of Defense. In addition to long range projection of speech for warning or instructional purposes, the devices are also capable of transmitting loud tones that can distract or deter personnel from approaching U.S. positions or vessels.
If misused, high frequencies and contact transducers would be very destructive. The ear is the most sound-sensitive part of the human body, so audible frequency sounds that damage the ear are the primary source of hazards. However, just deafening people isn’t fatal, if you’re talking about severe harm, as in weapons, other methods will be more valid.
The two primary things with destructive potential that would happen due to sound waves are
#1: kinetic – movement of tissues (as in infrasonic weapons, also the ear drum, inner ear etc.)
#2: thermal – necrotic changes to tissues (as in ultrasonic surgery)
There is also the argument that a single shockwave, a transient – as in a bomb going off – is probably the most commonly used acoustic phenomenon for causing harm to people. That is not a frequency, just a wavefront, and it will strike up resonances in anything it meets.
Maybe you’ve seen this in the news recently, but destructive sonic weapons are a real thing. The Independent (independent.co.uk) released this article putting the US at the helm of use of a sonic weapon attack Read the full article here.
The information used for this article has been found on websites, forums and the like. Do not take this as official medical information. Thank you for reading and please comment your thoughts on this post directly below. Namaste