USING A SOUND LEVEL METER
These instructions are for an analogue sound level meter. These all tend to look and work pretty much the same way, with minor differences... please ensure you know how to operate it correctly in order to provide the best quality of FST. Be aware that these give very rough guides and approximate readings only.
The function of the sound level meter in FST is to measure the loudness of the sound/ music being presented to the client in dBA.
This can be done by placing the microphone opening between the earphones as shown in the FST diagram (see the drop-down ‘menu’ section ‘volume calibration’(practitioner version of FST), or directions on-screen (home user version of FST).
Ensure that there is a fresh battery in the device, and check the battery power level by turning the yellow dBA knob ON to ‘batt’. There will be a reading on the VU meter screen to show whether the battery is powerful enough to use, when the needle rests in the green section. If so, proceed to the next stage, of sound measurement. If the needle indicates a flat battery (in the red) please replace the battery.
Turn the A / C switch to ‘A’
Turn the ‘fast’ / ‘slow’ switch to ‘slow’... this gives an averaged reading.
Turn the yellow dBA switch ON and keep turning through the clicks until it indicates 60 or its lowest reading.
Place the microphone of the Sound Level Meter where you want to measure the sound loudness.
Turn the sound source up slowly while watching the needle of the VU meter very closely. When the VU meter moves and mostly stays around the 0 mark,i.e. midway in the screen, that means that you have the sound at approximately 60dBA.
You can do this for each of the marked levels on the yellow round switch.
If the needle in the VU meter keeps mostly to the left of the midway mark , that means the sound is less than the setting you have on the yellow switch.
If the needle is to the right of the midway mark, it means you have the sound louder than the setting on the yellow dial.
These give a handy way to measure in-between levels, e.g. a rough measure of 56 would be 4 points to the left of the midway mark when the yellow dial is at 60, i.e. 60 – 4 = 56 (approximate).
You will be noticing how very much sound fluctuates in loudness, so the needle moves a lot, even in the ‘slow’ setting. One does not consider 1 to 6 dBA really significantly different in these measurements, but makes a ‘best guess’ at the reading. 10 dB however is an important difference.
Take your time to get to use the SLM confidently. Take it around and use it to measure the sounds in your environment, e.g. how loud you have the TV on!
Also get a feel for the spoken voice loudness levels in this way, and ambient noise levels in the workplace, restaurant or school room. You’ll be surprised!
