View Full Version : Device to measure sound volume and frequency

05-31-2008, 06:51 PM
This might seem like a strange question to ask here, but is there some sort of product that can accurately measure the volume and frequency of a nearby sound?

The reason I ask is because my MacBook has an uncomfortable high-pitched sound coming from under the keyboard, and after a full day of use (I was transferring files from one computer to another) I had developed a really loud ringing sound in my right ear that hasn't gone away. I've heard of plenty of reports of buzzing MacBooks online, but none of them appeared to be dangerous!

Basically I just want to see exactly how loud this noise is that emanates from my MacBook. If the sound does reach unsafe levels, I think Apple has some explaining to do - especially since it's pretty miserable having a loud ringing sound in my ears at all times...

By the way, this sound isn't related to the idle Core Duos, the power supply, or the screen being dimmed. The MacBook did have the buzzing problem when the processors were idle, but I was able to fix that by writing a program similar to QuietMBP. The remaining sound appears to be unrelated.

05-31-2008, 07:03 PM
Short answer: yes

check out this (http://www.noisemeters.com/). You could probably borrow one from your local authorities something like EPA or local council that has responsibility for building and planning. Hope you get the idea. If they wont let you borrow one see if you could bring the computer to them for a check.

06-01-2008, 08:33 PM
Thanks for the info. For the past day I was wondering how I'd ever be able to get in touch with someone from those agencies... until I remembered that my dad works for one! He said he has access to sound meters for measuring decibel levels, but he thinks the MacBook's problem is the frequency of the sound and not the volume.

Can high frequency sounds harm your ears too? If so, what types of devices can accurately measure that? Thank you!

EDIT: Oh, and I realize I'm asking a lot from a Mac forum, but I'm not really sure where else to ask the question...

06-01-2008, 09:22 PM
Never mind, it appears that only the decibel levels are considered dangerous. Hopefully my dad can bring a sound meter home for a day.

06-01-2008, 09:39 PM
High volumes of any frequency sound are considered dangerous.

By the way, if your father can't get ahold of an SPL meter, you can also buy one fairly inexpensively (~$50 USD) at your local Radio Shack. Hang on, I'll get you a weblink:


06-01-2008, 10:07 PM
Perhaps the software "SignalScope Pro" (http://www.faberacoustical.com/products/signalscope_pro/signalscope_pro_screenshots/)would be useful - it measures sound via your Mac's microphone.

06-01-2008, 11:40 PM
If I can't get access to a sound meter, I'll give that program a shot. Thanks!

06-05-2008, 05:33 PM
Well this is annoying... my dad was able to bring home a sound meter today and I tested it out, but it keeps saying there are no sounds coming from my MacBook. I then asked my dad to listen and he too said the computer was dead-silent. I hear a very high-pitched wailing sound whenever the computer is turned on; putting the computer to sleep and turning it off makes the sound go away. It's clearly coming from under the H key on the keyboard.

One weird thing is that I haven't heard the loud buzzing sound at all yet (from when the CPUs are idle), but Mac OS X might be doing some maintenance in the background seeing as how it's been a few weeks since I last used the computer. Maybe the sound meter will pick up on that once it returns.

06-05-2008, 06:26 PM
On the sound meter does it say what its frequency range is? As you hear it and not your father I would guess that it has a high frequency that is above what the sound meter and your father can "hear". My guess would be that its somewhere above 10kHz and only good equipment/microphones will catch that.
One place also you could try to check is your local hospitals ENT department they might have better equipment. Perhaps if you're still in school you might have a school nurse that might help with contacts.
Good luck.

06-05-2008, 07:40 PM
I agree. Your father, depending on his age, probably can't hear above about 13000 Hz, probably even lower in his left ear. And you, also depending on your age and how many times you've been exposed to high volumes for extended periods, can still probably hear up to around 16000 or 17000 Hz. So a sound in the 13000 - 16000 Hz range could be heard by you but not your father.

Any decent microphone can pick up stuff in the 13000 - 16000 Hz range, but SPL meters aren't going to give those frequencies a lot of weight--they're not really designed for that. If you have access to something that measures sound by frequency, instead of an SPL meter that just gives you an overall dB reading, that should tell you what you're trying to figure out.


06-05-2008, 08:34 PM
BTW, here's an interesting read:

And click here for a sound sample (I tested it and it works):

06-06-2008, 02:15 PM
On the sound meter does it say what its frequency range is?
Up to 8000 Hz. Dang. :(

I've been checking Google for a while, but I can't seem to find any noise meters that work for high-frequency sounds. Wait, is that because high-frequency sounds are no longer considered noise since it can't be heard by many people? Maybe I'm supposed to be looking for another device entirely.

I guess I'll give that software program a shot later. Hopefully my MacBook's microphone is sensitive enough to pick up all of its sounds.

Thank you so much for all your help so far! I really appreciate it.

06-06-2008, 04:26 PM
Wait, is that because high-frequency sounds are no longer considered noise since it can't be heard by many people?

No. People generally consider noise to be between 20 Hz and 20,000 Hz, even though only the very young and a few rare standouts can really hear 20,000 Hz. (Many people think that they can hear 20,000 Hz, but unfortunately they are mistaken.)

Maybe I'm supposed to be looking for another device entirely.

Yes, to find the frequency of a sound, an SPL meter is the wrong device. And to measure the amplitude of a high frequency sound, an SPL device is not exactly the right device either.