Call Blasting Protocol

Courtesy of the MABRC

Call Blasting Protocol

While Call Blasting is debatable on it’s effectiveness in the field, MABRC Researchers continue to use it on occasion. From purported Bigfoot vocalizations from around the world, to primate vocalizations, and even baby crying audio.

To conduct Call Blasting and document it for proper review, the MABRC has produced protocols and procedures for researchers to guide them.


There are two types of documentation required with respect to call blasting efforts:

* Written documentation.
* Audio/Video recordings.

Written Documentation

The notes or narratives of each outing where sound blasting was performed must include the following details: what happened (a basic log), who was there (names and contact info.), the location (specifically), the terrain, the date, the time-frame, the weather conditions, the history of reports in the area, the accessibility of the area (i.e. legal accessibility, vehicle accessibility), whether there are homes within ear-shot of the call blasting, and anything else that may be scientifically or historically relevant.

Audio/Video documentation

The outing should be videotaped: the people present, the location, the equipment used and anything else that may be historically or scientifically relevant. This record must have someone speaking to the camera, listing the details required in the written documentation (i.e. location, time-frame, local history of reports, etc.). This must be a separate tape from the tapes used to record response vocalizations.

Procedures for Recording Sounds

At least two sound recording devices (which can be camcorders, but preferably high quality digital voice recorders) must be running the whole time the team is on location after dark. The Bigfoot might vocalize before any sound blasting is conducted, so recordings must be made when not blasting sounds.

Do NOT try to record Bigfoot vocalizations by hitting the "Record" button when sounds are heard. Sounds will be missed that way. The recorders MUST be running every moment after dark. Recorders should be started at different times. The recording periods must be staggered so that at least one recorder is running when the tape is being swapped or rewound on the other recorder. A recording plan must be developed in order to do all this in an orderly fashion (include that plan as part of the written documentation). If using digital audio recorders, then using tapes become a non-issue.

If using camcorders, follow this procedure.

Several tapes will be needed for each recording device. Each tape has to be labeled appropriately before it is put in the recorder. Mark the tape with the date and time of the first recording session and each date and time the tape is used after that, if at all. Don't reuse any single tape on more than five outings. Consumer-grade digital tapes have degraded sound after being recorded on a few times. Buy new ones every so often. They are cheap. 

If no responses are heard before a tape reaches the end of its spool, rewind that tape and start recording again. If any sounds are heard while a tape(s) is recording, let it continue to record to the end of the spool, then swap out the tape and mark on the label the time it was taken out of the recorder. Also mark it to indicate that it may have vocalizations on it. Review the tape later, in a dry, well illuminated, relatively dust free location.

Don't ever rewind and replay the relevant section of a master tape over and over repeatedly.

This should only be done with copies or computerized versions of the clip. People ruintheir precious master tapes by repeatedly playing and rewinding an important clip over and over, in order to play it for their friends, before they’ve made backup copies. Don't check to see if a sound was captured on tape while still outdoors. You can check to see if the tape recorded any sound at all, but once you’ve determined that then simply have faith that the relevant sounds were captured as well. You either captured the sound or you didn't. Wait until you are indoors, away from moisture and heavy dust, before reviewing the tapes.

Powering Recording Devices

Adequate power supplies for each recorder will be needed because of continuous recording throughout the night. There are multiple ways for doing this; choices for extended power depend on the recording devices used. Cassette recorders are easiest because they'll go all night on the batteries put inside them. If not, the batteries can be quickly replaced.

Camcorders are more difficult in this regard because the batteries and power accessoriesare more expensive and have a shorter duration. If there are multiple vehicles and cigarettelighter adapters available, these devices can be powered that way. Camcorders will not rundown a car battery. Another option is to have three camcorder batteries for each unit and abattery charger connected to a car cigarette lighter. Yet another option (preferred) is to usedeep cycle batteries with AC/DC inverters. Deep cycle batteries (boat batteries) will last aweek or more if only powering camcorders or cassette recorders.

The Recording Plan

Having a thorough recording plan means knowing the types of devices that will be on hand and having: an adequate number of tapes for each device, an adequate labeling process for the tapes, adequate power supplies for each device, a list of all needed accessories, a plan for staggering the recordings after sundown so that at least one recorder is always running, the knowledge of exactly how long each device will run before a tape is finished or a battery needs to be changed.

Recording devices should be placed several yards from each other and several yards behind the sound blasting gear. If possible, use plastic tote boxes for the recorders. A recorder can be placed on top of a tote box during dry weather and inside the box if the night air gets too moist (with an external mic hanging out from under the edge of the lid). If possible, have an external mic taped to a tripod so it's a few feet away from the recorder when the recorder is in the tote box. In that way, the microphone will be higher in the air and won’t record the sounds of the recorder’s motor noise. 

While recording, have someone with a wrist watch walk up to each recorder every quarter hour and clearly whisper the time near the mic. For example, “It is now 8:15 p.m.”


Get the best possible microphones to use with the recorders. Almost all camcorders have jacks for external microphones. External mics are preferable because built-in mics always record some level of recorder motor noise. That noise can be heard when one cranks up the volume of a tape. This is particularly essential when recording faint sounds, because the volume of the tape will need to be cranked up rather high during playback in order to hear these sounds clearly.

No one can be touching the device or the microphone during or after the sound blasting. If the recorders are sitting on the hood or roof of a vehicle, then no one can be sitting inside the vehicle. Movement inside the vehicle will cause loud knocking and creaking sounds on the tape.

If people need to sit inside the vehicles, then the recorders should be at least 30 feet away from the vehicles. The recorders should be at least 30 feet away from people anyway, to prevent their reactions to vocalizations from overriding the recording of the vocalizations themselves. The participants have to be trained and prepared to keep quiet for long enough after any vocal responses are heard so as not to screw up the future usability of any good recordings obtained.

Other Procedures


If possible, you will put people on each side of the ridge or mountain top with walkie talkies. There is no technical process for triangulating the position of a sound source. It's all done by ear and judgment. All of the different listeners simply say which direction the sounds came from. They'll narrow it down greatly that way. Technical triangulation is thwarted by echoes and the relatively limited areas involved.

If you have multiple recorders placed out away from your base area, these could technically become triangulation devices, as you can listen to the sounds being recorded and compare them with the other recorders.

Controlling Distractions

Be as quiet as possible. Do not speak or move after the call blasts. This will help you and your field partner to hear what is going on!

When call blasting, the following procedures should be used.

* Upon arrival, if possible, make sure that no one is in the immediate vicinity that could be alarmed at your call blasting.

* If anyone is in the area, document their location for reference.

* Play the call at half volume, this takes away the majority of the static when playing at full volume and alerting the local Bigfoot that it is a fake call. The best time to call blast is at the top of the hour and every thirty minutes afterwards. This way, if someone reports hearing a vocalization in the area, you can discover whether they heard your call blasting or a real vocalization by what time they heard it.

* You want to play a minimum of 2 calls, and a maximum of 5 calls in any series. Depending on the length of the call being used. The longer the vocalization of your call, the less number of times you want to repeat it.

* Document the time, which direction, what call you used, and what the response was. Have your recording equipment going during the call blasting, as some responses may occur immediately.

* The two biggest problems I have witnessed with call blasting is that the people can not be still. Some one will shuffle their feet and someone will feel the need to talk. This is distracting to those trying to listen and often will be picked up on the recorder over a faint vocal. So as mentioned train yourself to be quiet.