Equipment » Sonic Tomograph

ENSPEC uses the technologically advanced and highly sophisticated PiCUS Sonic Tomograph (ST) to accurately measure and assess the internal wood structure and strength in trees or other wooden structures. The PiCUS ST is a non-invasive instrument that works by passing sound waves through wood. Because the speed at which sound travels through wood is determined by the quality of the wood it is passing through, it is possible to detect areas of solid wood, areas of decay or cavities in a tree.

ENSPEC Sonic TomographENSPEC Sonic Tomograph

Fungi, pathogens and insects can attack and destroy the internal wood of a tree and compromise its structural integrity. Because internal damage to a tree is often not visible from the outside, it can be difficult to detect and assess; most tree failures are associated with fungal, insect or pathogen attacks.


The presence and extent of fungal, insect or pathogen invasion in trees can be quickly detected and accurately measured with the PiCUS ST. The early detection of decay and cavities in trees means that tree risk and health can be assessed and addressed in a timely manner.

ENSPEC Sonic TomographENSPEC Sonic Tomograph
The PiCUS ST uses a set of sensors (up to 30) that are placed around the trunk at the height being tested.  The sensors are evenly spaced around the trunk and are connected by wires to record the sound transmitted through the trunk. Each sensor has a corresponding metal pin that is inserted into the trunk and then tapped with a hammer to create sound waves that travel from the tapped pin to all the sensors. Each pin around the trunk is tapped in turn and the test continues until all pins have been tapped with the hammer. The number of pins used is dependent on the size and shape of the tree at the test point.

The sensors around the trunk quickly measure the velocity of the sound waves that pass through the wood. Any variations in sound velocity are detected and can be linked to wood quality because sound velocity is different in solid wood, decayed wood or cavities.

ENSPEC Sonic TomographENSPEC Sonic Tomograph
All sensor data recorded during the test is transmitted via Bluetooth to a computer for analysis. The sophisticated PiCUS professional software converts the sound data to wood quality values and the internal properties of the tree cross section are mapped on a colour image called a tomogram. The colours indicate solid wood, decayed wood and cavities and clearly show the location and extent of any damage.

Skilled ENSPEC staff interpret the tomogram image, assess the structural integrity of the tree and identify the pathogens attacking the wood. The comprehensive and professional report that is provided to the client may be used by managers to identify and risk manage a tree that has internal defects that could lead to tree failure causing injury or damage to people or property. Alternatively, the evidence in the report may save a tree with suspected internal defects from unnecessary remedial works or removal.

Due to the sophisticated and complex nature of the PiCUS ST, the level of operator competence is crucial to its successful application. ENSPEC only employs highly trained and fully experienced operators to guarantee the integrity of the field tests and data interpretation and analysis. Clients can have full confidence in the veracity of ENSPEC’s PiCUS ST testing and reporting.

The PiCUS Sonic Tomograph offers an excellent non-invasive diagnostic instrument to evaluate and assess the internal structure of trees, and complements ENSPEC's comprehensive range of diagnostic equipment for assessing trees and all wooden structures.

ENSPEC continues to utilise innovative equipment and methods that assist in creating safe environments and preserving trees.

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