around the microphone , the amount of dust clogging up the mic , and any number of other factors . Apps are decent at providing relative assessments but out of 10 cellphones , you ’ re likely to get 10 different levels from the same app because all phone are not created equal . There ’ s not an easy way to calibrate most apps ; therefore , the information they provide is not verifiably accurate .
These devices typically generate a 1 kHz sine wave at specific levels . The one I use can generate a 1 kHz tone at either 94 or 110 dB right into the mic capsule when the device is slid over the capsule . Once the calibration device is over the mic capsule , the software calibrates the SPL meter to match the 94 or 110 dB tone . After that procedure , the meter readings can be trusted and any log that ’ s captured on a time line can be substantiated .
Most smartphone decibel meters provide a setting that lets the meter be calibrated . Once you ’ ve calibrated the settings on the app so that the readings match Smaart , you can trust the SPL reading on the app .
Covering everything about software analysis tools is a big topic for another time , but these tools are a very important component in the live sound operator ’ s kit .
Mics used to calibrate decibel meters have small omnidirectional condenser capsules with a flat frequency response across the audible spectrum .
Software such as Smaart is made to pair with a calibrated microphone — a very smalldiaphragm condenser mic with a flat frequency response . Even when using a calibrated mic with analysis software , the measurements aren ’ t necessarily accurate until you calibrate the system using a sine wave generator designed to fit over the microphone capsule .
The calibrator is a tone generator that fits over the mic capsule . Simply calibrate the software for the appropriate SPL ( 94 dB @ 1 kHz for Smaart ) and the metered SPL can be trusted .
Travelling sound operators soon learn that different venues have different volume restrictions . Exceeding those restrictions can at the very least , get you in trouble with the venue manager . At worst , you could find yourself with a stiff penalty or maybe even at the wrong end of a lawsuit . Therefore , using calibrated software to keep track of the volume for the complete length of a performance is a great way to make sure you have trusted and verifiable records for all to see .
As a side benefit , once Smaart is calibrated and verified as accurate , simply play a 1 kHz sine wave through the sound system until the Smaart SPL meter reads 94 dB , or there abouts , and adjust the “ calibration ” setting on your smartphone decibel meter ’ s “ Settings ” page so that it matches the measurement on Smaart .
EARNING THE TRUST OF THE TEAM If the instrumentalists and singers hear that the sound was good during the performance , they will soon develop trust that they are in good hands . If they hear that the sound isn ’ t very good , or if they ’ re told certain instruments or voices aren ’ t being heard , they ’ ll quickly lose trust in the sound operator , especially if they ’ re the ones being left out of the mix .
If the sound operator expects to gain the trust of the team , he or she must learn to do a good job . This book will help a lot , but the techniques must be practiced , and the principles must be applied .
Sometimes the factors leading to a negatively perceived mix are outside the sound operator ’ s responsibility set . Sometimes an instrument must be understated in the mix because the instrumentalist is musically undependable . As the musicians get better at playing musically and providing a more consistent source for the operator to mix , everyone will appear to be better at what they do , including the sound operator .