6
MICROPHONES
TRI-PODS
When a sound wave hits a hard surface like a sidewalk or driveway, the sound
wave reflects off and is much smaller than the initial wave. The difference in the
two waves is transferred to the hard surface. The hard surface is now acting like the
old phonograph record and an electronic pick up can be set on the surface that will
reproduce the sound. Connect a microphone to a tri-pod using a 10 inch extension
tube and stand it on the hard surface. The energy or vibration in the hard surface will
activate the microphone so the thump can be heard.
NOTE:
Background noise can be a problem when working over asphalt or
concrete. In some cases this can hide or mask the sound of the “thump”.
NOTE:
Tri-Pods do not work well in soft soil conditions. Pushing one or more
of the tri-pods legs into the soil can sometimes work well enough that the earth
spikes are not needed.
EARTH PROBE SPIKE
To solve the types of problems encountered with Tri-Pods on surfaces that are not
solid, Aqua-Tronics developed the Earth Probe Microphone Spike for use in soil,
water, snow and other soft materials. By inserting the metal spike through the surface
skin, or top layer of soil, sound waves from the thump can be detected before they
have a chance to reflect from the soil surface, or disperse into the air.
Earth probe microphone spikes also eliminate many background noise problems.
Sound waves originating at the cable fault travel directly through the soil to the earth
probe microphone spike. Because they greatly reduce background noise, the earth
probe microphone spike should be used when possible. If a cable route lies under a
sidewalk, using an earth probe microphone spike off to one side of the sidewalk will
allow the operator to hear the thump more clearly.
FOOT PROBES
EARTH PROBE MICROPHONES ARE NOT LAWN DARTS AND SHOULD
NEVER
BE DRIVEN OR FORCED INTO HARD SOIL, OR FROZEN GROUND.
Cantilever damaged can occur where the earth probe spike screws into the
microphone bulb if the earth probe is not being inserted into the soil in a vertical
(straight up and down) direction. Damage can also take place if the earth probe spike
is not screwed up solid to the electronic bulb.
To eliminate the above possibilities, a unique foot probe has been developed to use
with the earth probe microphones. The operator can push the microphone into the
ground with his/her foot, using as much force as needed without placing undo stress
on the microphone bulb.
NOTE:
Hammerhead probes are available for extreme soil conditions.
