posted
Alright we all know that the name of the game is Sound Pressure level right. But have we over thought the issue? Is it really about the pressure?
When we're measuring out vehicles output, we're going for how "loud" it is right. Well I just got my Termlab and have been playin around with it. And it is infact about the pressure. But in reality is it really?
I took a whistle inches away and blew as hard as I could. Obviously over 104dB but only reading the minimum on the sensor.
Let's take lightning for example. We know its EXTREMLY loud, but it's safe to say that if the sensor was about 50ft away it would hardly pick it up. I don't really want to get into the deep physics of heating air mnolecules and ish but really.
How can we say these sensors are accuret to how loud something REALLY is?
I've tried searchin on something like this but cant find any answers. Are the sensors fit for the job?
-------------------- - Posts: 12464 | From: BC, Canada soon CA, USA | Registered: Oct 2001
| IP: Logged |
posted
Try moving the sensor from the corner loaded dash position that is deemed "legal" and place it at the listener's head position and see what happens to your score.
posted
Put the sensor beside your ear. Hole facing out. Light a big fire cracker 2" away. And tell me it's not louder than 110dB.(or whatever the sensor reads at with "no" sound.
I'm not up to date with my what reads what statistics, but I'm keepin it basic
I know people have opend these things up, and was wonderin if theres any pics of whats inside. I know it's nothing special. Is it just a hole wires and some kind of microchip?
-------------------- - Posts: 12464 | From: BC, Canada soon CA, USA | Registered: Oct 2001
| IP: Logged |
quote:Originally posted by tommyk90: What about the frequency of the note?
I'm not sure the termlab is capable of picking up 5000 hz+ frequencies.
This is probably true.
One thing I noticed that blowing into it can only go ato high 20's. But when i put it infront of my computer port it got to mid 30's. It's weird how it was louder but had half the pressure or velosity. Would this have to do with frequencies?
-------------------- - Posts: 12464 | From: BC, Canada soon CA, USA | Registered: Oct 2001
| IP: Logged |
posted
the mic measures sin waves not shock waves. shock waves can be much more intense than a sound wave but wont show up on a spl mic
Posts: 62 | From: Fort Pierce, Florida | Registered: Jan 2005
| IP: Logged |
posted
but,if it reads pressure why can you take a light and shine it into the sensor and it will read,
-------------------- RODNEY BUSCH, TEAM SHOCKER! TEAM GATES www.splmaxcup.com 2000 RAN STREET 1-2 WHEN IT HAD A 600WATT LIMIT 4 dr trunk car, 2001 DIDNT WANT TO GO, TO MANY VANS WITH AMPS UNDER THE HOOD.4dr trunk car 2002 WORLD FINALIST STREET 1-2 ERTIFIED 148.3 1 AMP 4DR TRUNK CAR. 2003 WORLD FINALIST STREET A, TEAM MEMPHIS FORCE, 2004 DIDNT MAKE FINALS BY 2 POINTS 2004 MECA WORLD FINALIST, 5TH S2,MEMPHIS FORCE, 151.9, 2ND RSPL 2005 WORLD FINALS 7TH PLACE STREET B 152.1 (WE WON THE 3 WAY TIE, DID A 152.5) 2006 world finalist, bad head unit, Posts: 1553 | From: OHIO,SPL COUNTRY | Registered: Jan 2001
| IP: Logged |
posted
Term-LAB will not measure frequencies above 250 Hz. Also, to achieve the extreme precision (1 Hz resolution) on the low-frequency RTA, the sampling period is 1 second. The result is that Term-LAB is not suitable for measuring impluse-type sounds such as hammer-blow, firecrackers, etc.
Term-LAB was specifically designed to measure low-frequency sound such as that used in dB Drag Racing.
With regards to the "pressure" issue, sound is simply variations (or modulation) of a static pressure value. Term-Lab sensors only look at the variations (or magnitude) of the pressure variations. The magnitude affects the SPL and the rate at which the variations take place are determined by the frequency.
-------------------- "Keep it Loud and Make me Proud!"
posted
Presure transducers like that are used in a termlab acheive that accuracy (notice how most termlabs are pretty close in measurement to one another, reguardless of how many you compare) because the bandwidth of fequency sampling is very narrow. See, you always have a tradeoff in senseing equipment like this, you either have a huge bandwidth of measurment with moderate accuracy, or a small band of measurement with high accuracy, you cant have it both ways.
-------------------- Posts: 699 | From: Fort Knox, Kentucky | Registered: Feb 2005
| IP: Logged |
![[Confused]](confused.gif)
![[Razz]](tongue.gif)
Printer-friendly view of this topic