AN ANALYSIS OF THE LOW FREQUENCY ACTIVE SONAR SOUND

 

 

I have been concerned about the effects of the Low Frequency Active Sonar project being tested by the US Navy and others. The deployment of the LFAS is still being debated by Congress and the National Marine Fisheries Service (NMFS) and a full decision on testing and deployment has yet to be made. I trust that the analysis presented here can aid these deliberations.

 

The data shown below is the first I know of that shows what the LFAS sound actually "looks" like in terms of pitch, amplitude, harmonics (formants) and sound spectrograms ("voiceprints"). As you can see, most of the power in the sound is in the band below 100 Hz, and considerable power is in this band.

 

As my former analysis of bubble resonance & displacements showed, the lower LFAS frequencies can be most damaging. The analysis presented below confirms my concerns that the LFAS sounds can damage Cetacea, humans (especially children and women with smaller lung volumes) and other creatures.

 

Even in this time of a - yet to be declared by Congress - "war", we must mitigate the effects on our planet of our military and government activities.

 

The US Navy seeks to be fully exempt from all regulation of the LFAS and other technology, especially in time of war. Yet it is clear that government and military activities can be massively harmful to our planet, even in peacetime. For example, sounds of high intensity from LFAS, biotoxins, depleted uranium, mines, etc. as well as the overall activity of the military, such as the continued bombing of Makua on Oahu, the island of Ko'olawe, and Vieques, in Puerto Rico, etc. (while considered necessary by the Navy) certainly harm our shared environment. Yet, this is seldom considered in environmental forums because the military and government often exempt themselves from our laws and our Constitution. However justified this may appear to our officials, this is one of many situations that must be solved for us to have viable ecosystems on our planet.

 

You may hear the LFAS sound sample IF the following plugin works. For some reason, this usually works in Internet Explorer, and fails in Netscape.

 

I encourage you to download the .wav file to play it on your system. The following is a plugin that should play an MP3 version of the LFAS sound sample from DolphinEar.

 

 

 

The LFAS Test sound used comes from www.dolphinear.com and a .wav file can be downloaded here or, if you click this in Internet Explorer, it should open a sound player.

Otherwise, you can "save target as" to save the .wav file.


As you can hear, this is a strange sound, very abrupt, loud, pulsing and low frequency.

At levels of about 155 dB, it seems that dolphins and Cuvier Beaked whales were injured or killed. (see my letter to the National Marine Fisheries Service on LFAS, written with the help of Dr. Lee Tepley)


In particular, the current analysis shows much of the LFAS power is concentrated near and below 100 Hz. If you look at the table of Resonances and Displacements, you will see that in many cases the resonances for lungs as well as ear cavities and skull sinuses are near 100 Hz or below. Therefore, the current analysis shows why the observed damage to Cetacea and humans may be occuring.


Sincerely,

Michael Hyson, Ph.D.

Puna, Hawai'i
November 8, 2001

Plot of the sound as amplitude vs time (clipped)

 

Pitch vs time for test LFAS tone.  Most of sound is about 175 Hz

 

 


Power Spectra (relative Power in dB vs Pitch) from formant analysis

 

 

 


Spectrogram of the LFAS sample sound
(F vs time, with darkness proportional to power)

 

Formant track of the LFAS sample
(showing lowest formant (pitch) and higher harmonics up to 4500 Hz)

 

 


Intensity in dB vs time for the LFAS test tone

 

 

Pitch vs time for the 0 to 500 Hz band (linear plotting)

Note the sharp "dips" in pitch to near zero frequency.
* If these are real, as opposed to possible defects in the pitch tracker used, then there is the potential for high power "spikes" in infrasonic bands known to damage tissues.*

 

 

 

Pitch vs time for the 0 to 200 Hz band (linear plotting)

 


Pitch vs time for the 0 to 300 Hz band (log plot)

 

 


Formant Contours (0-5000 Hz)

 

Power in dB for 0 to 300 Hz
Note the large relative power in the region below 100 Hz