SCL Launches New Calibration Service for Artificial Mastoids

The Standards and Calibration Laboratory (SCL) has recently established a calibration system for Artificial Mastoid, a specialized device that replicates the mechanical characteristics of the human mastoid bone, located behind the ear. This device consists of a dome-shaped structure designed to approximate the mechanical impedance of the human mastoid. It includes a built-in force transducer to measure the force applied by a bone vibrator, enabling the simulation of sound transmission through the human mastoid in response to auditory stimuli. The primary application of Artificial Mastoids is to calibrate the bone conduction channel of audiometers, which are essential for audiological assessments.

Previously, users of Artificial Mastoids in Hong Kong had to send their devices overseas for calibration, a process that was both time-consuming and costly. With the establishment of this calibration system at SCL, we now provide a local solution that eliminates the need for international shipping, thereby streamlining the calibration process. This new service involves precise measurements of mechanical impedance and force sensitivity, ensuring that audiology professionals can maintain the accuracy and reliability of their equipment with greater efficiency.

Mechanical impedance refers to the resistance an object exhibits when set in motion. Force sensitivity, on the other hand, describes how an object reacts to an applied force, determined by both the measured mechanical impedance and the output charge of the Artificial Mastoid under test. The output parameters from the Artificial Mastoid are measured to compute its mechanical impedance and force sensitivity, which is controlled by an in-house designed software that automates the process. The calibration range of this system spans from 125 Hz to 8 kHz, with the calibration and measurement capability ranging from 0.4 dB to 1.2 dB.

For more information about our acoustics related calibration services, please visit the SCL’s website at www.scl.gov.hk.