Audio analyzing software

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Peternap

Well-known member
The Azden thread got me thinking about analyzing some of my mics under the conditions I use them in.

I enjoy Chad's reviews because they're very detailed and through. Chad is a musician though and most of my audio work is done under the worst field conditions possible and consist of Dialog only......In case anyone's wondering, I have a thick skin too:grin:

I do use some Mic's that would make a lot of audio experts cringe. For instance I use a Sennheiser ME-3 plugged into an H4n, for some commentary because of the noise rejection. (Before anyone brings it up, I shortened the collar on all my Sennheisers that have it, so they work with other equipment).

I also use a variety of reporters mics again because of the noise rejection. Bangs, clangs and rustle worry me a lot more than the cleanest frequency above the human voice.....

But, I've never actually sat down and looked at how the mics are responding at a particular frequency. What is a good software package to use for this?
 
Using a Real Time Analyzer (RTA) is the first stop. There are hardware versions used to analyze and tune rooms, or there are plug-in versions for either your favorite DAW or stereo waveform editing program.
 
Peternap said:
But, I've never actually sat down and looked at how the mics are responding at a particular frequency. What is a good software package to use for this?
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I would also ask about how a reference tone or chirp is generated and measured... and what sort of anechoic chamber is used...
 
We did a lot of testing at my last company. We used some pretty intense software for testing, but you won't need that, as you won't be looking at things from a component level. For our "rough" tests, we used CoolEdit/Audition (Adobe). It was pretty good for plotting freq charts.

As to the reference tones/chirps, I am trying to find where I got my CD for testing. It has all 31 bands of tone (each with different lengths), pink noise, white noise, chirps, pulses, etc.

But for your test to be accurate, you need to have accurate monitors and signal chain. Most stuff out there right now has coloration, which is good for everyday audio usage, but bad for testing. You need a FLAT 20-20k monitor at the very least, otherwise your tests will have that skew in them.

Anechoic chambers for audio testing are very pricey to build properly, even the small ones. You have to not only kill every reflection, but you have to isolate them from external noise. And that is tough to do cheaply.

You'll need to figure out how accurate you want to go. If it is for just personal reference, you probably don't want to throw too much money at it, because it gets pricey.
 
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FYI, software based analyzers will only be as good as the reference microphone used. Using a microphone with non-linear response will provide false data.

Most of us have abandoned RTAs in favor of FFT-based analysis tools such as SMAART. These tools allow the user to address impulse response anomalies ocurring in the time domain. The advantage of this approach over RTA is that when using only RTA-based measurements, corrections via equalization will only be valid for one point in a 3 dimensional space.

Now that I've totally complicated the issue, I usually let me ears tell me how a microphone is responding in a particular environment and with a particular source.

Alex H. said:
Using a Real Time Analyzer (RTA) is the first stop. There are hardware versions used to analyze and tune rooms, or there are plug-in versions for either your favorite DAW or stereo waveform editing program.
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Prosonus sells or used to a CD with a series of tone sweeps and noise filtered to various bands etc.
All the expensive toys are important if your doing real testing. I would suggest that what your really looking to do is to get a rough idea of how your mics stand against others. In that case the chamber and even really flat monitors are much less critical. But you do need to get or borrow a "standard" to compare to, a decent omni might be a good choice. Get that "standard" mic set up and get as flat a response as you can out of your system. After that your looking for differences not absolute values so you can be pretty accurate even if the conditions are not particularly scientific because things like room acoustics and speaker power curves are going to be the same for all the mics. Just remember to just compare differences.
 
Noiz2 said:
I would suggest that what your really looking to do is to get a rough idea of how your mics stand against others.
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Thanks Noiz!
That's exactly what I'm after and it's more out of curiosity than anything else.
My narration is mercifully short. I have others do most of it. My voice has been described as gravelly, scary and abusive...so I'm not too concerned about accurate reproduction of myself.

The people I interview (That's being kind) range from actual field interviews to hidden mics and way too many recorded telephone calls on cell phones... which are hard to get right.

The environment is always noisy and sometimes outlandish. I once interviewed a somewhat colorful Motorcycle Club member with a GoPro on my helmet and a wireless Lav behind each of our windshields, on a winding road in the mountains.....so my mic concerns are varied.

I would like to see how each one actually stacks up on paper (figuratively) though.

One of my favorite general purpose mics seems to be one of the least popular around. A Rode M3. For some reason I get more usable audio with it. I'd sort of like to see why it seems to out preform my ev635 or pr35.
 
As Noiz said, you don't need a scientifically accurate anechoic chamber to test your mikes in your control room/production space; just reasonably flat monitors and the gear that you normally use. Set EQ's flat and test away...

Re: cell phone interviews-- How are you doing these? Do you use a phone interface?

GJ
 
Gregg Juke said:
Re: cell phone interviews-- How are you doing these? Do you use a phone interface?

GJ
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Stick a Lav in the same ear I hold the phone over:huh:

I wouldn't exactly call the phone recordings..."Interviews" it's usually someone saying something they shouldn't. I have the Clerk of a locality that I'm doing a Very long and uncomplimentary Doc about...calling her assistant's actions "Suspicious". She didn't know she was recorded and later stated in court, the incident never happened.
 
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I'd be careful with those kinds of recordings-- if you're not a lawman with a warrant, or a newsman under very special circumstances (and it sounds like you're not), that sort of thing can get you in trouble.

If you do any phone interviews that are more "legit" (for lack of a better term), and where the "participant" has given informed consent, there are some pretty inexpensive and decent interfaces out there (a couple hundred bucks).

GJ
 
Gregg Juke said:
I'd be careful with those kinds of recordings-- if you're not a lawman with a warrant, or a newsman under very special circumstances (and it sounds like you're not), that sort of thing can get you in trouble.

If you do any phone interviews that are more "legit" (for lack of a better term), and where the "participant" has given informed consent, there are some pretty inexpensive and decent interfaces out there (a couple hundred bucks).

GJ
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Not in Virginia. It's a one party consent state.
As long as you're a party to or have the consent of one party, it's legal.

Some states are a PITA....that's why I don't go there.
And yes, I do have a news service and have clearance including the General Assembly. That doesn't give anyone any special telephone recording privileges here though. The big advantage is being able to cross police lines.

[h=3]Virginia Wiretapping Law[/h] Virginia's wiretapping law is a "one-party consent" law. Virginia makes it a crime to intercept or record any "wire, oral, or electronic communication" unless one party to the conversation consents. Virginia Code § 19.2-62. Therefore, if you operate in Virginia, you may record a conversation or phone call if you are a party to the conversation or you get permission from one party to the conversation in advance. That said, if you intend to record conversations involving people located in more than one state, you should play it safe and get the consent of all parties.
The wiretapping law does not cover oral communications when the speakers do not have an "expectation that such communication is not subject to interception under circumstances justifying such expectations." See Virginia Code § 19.2-61. Therefore, you may be able to record in-person conversations occurring in a public place, such as a street or restaurant, without consent. But you should seek the consent of one or all of the parties before recording any conversation that an ordinary person would deem private.
 
Peternap said:
Not in Virginia. It's a one party consent state.
As long as you're a party to or have the consent of one party, it's legal.
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I'd also recommend hiring a graduate from the Rose Mary Woods school of telephone transcriptionists. They are specially trained to accidentally erase important portions of telephone transcriptions, when required to make such for opposing legal counsel.
 
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