How do you play test tones in the field for impulse response generation? at DVinfo.net

Emre Safak · November 9th, 2007, 07:31 PM

I am learning about how to create my own impulse responses for convolution reverb. I have the test tones, but I do not know how I would play them in the field. It sounds like so much hassle compared with popping a balloon or firing a toy gun. Does it really sound better? Is the idea in the rising sine-wave method to capture the impulse response at all frequencies? How does it technically differ from the impulse method? Doesn't the sine wave method require silence for the duration of the test tone? What happens, for example, if some noise goes off during the recording/playing of the test tone? Wouldn't that ruin the impulse response?

Gerry Gallegos · November 9th, 2007, 09:42 PM

Convolution samples "Need" to know what the source is to know how to compare an behave with them. so they have to have a baseline comparison for them to give an accurate example of the sound scape.

Emre Safak · November 10th, 2007, 01:53 PM

I could not relate what you said to my question.

Emre Safak · November 30th, 2007, 08:54 AM

I'd like to try one more time!

Does anyone actually use a sweep generator? How much does yours cost and is it portable?

Chris Barcellos · November 30th, 2007, 11:02 AM

Emre:

Not sure what you are asking, and I am a novice at the sound side, but used a 1 k tone generated by the audio mixer in a movie I was DP on earlier this year. I since bought a tone generator from BH that plugs into XLR port to set levels. It has several different tones. Don't have any idea if that is what you are after.

Emre Safak · November 30th, 2007, 11:14 AM

Thanks for responding, Chris. The way it works is that you play a sine wave rising in frequency (a "sweep") and record it. I'm interested in how well it works (since practical environments are unlikely to be quiet for the duration of a sweep). The tone is not of a fixed frequency.

The generators I'm finding on Google are much higher-specced (on the frequency scale), and consequently much-higher priced, than I need.

The alternative is to get a speaker and play a sweep recording. I am concerned that this method will critically depend on the quality of the speakers (since their frequency response will get convolved into the recording). Also I do not know how I would lug around a receiver to power and feed the monitor. It sounds so impractical, that is why I was wondering what people do in practice. Popping a balloon sounds (forgive the pun) so much more convenient.

Chris Barcellos · November 30th, 2007, 11:19 AM

This is what I got, if it helps anything:

http://www.bhphotovideo.com/c/produc...ion_Audio.html

November 9th, 2007, 07:31 PM	#1
Emre Safak Trustee Join Date: Feb 2004 Location: Brookline, MA Posts: 1,447	How do you play test tones in the field for impulse response generation? I am learning about how to create my own impulse responses for convolution reverb. I have the test tones, but I do not know how I would play them in the field. It sounds like so much hassle compared with popping a balloon or firing a toy gun. Does it really sound better? Is the idea in the rising sine-wave method to capture the impulse response at all frequencies? How does it technically differ from the impulse method? Doesn't the sine wave method require silence for the duration of the test tone? What happens, for example, if some noise goes off during the recording/playing of the test tone? Wouldn't that ruin the impulse response?

November 9th, 2007, 09:42 PM	#2
Gerry Gallegos Major Player Join Date: Oct 2007 Location: Houston, Texas Posts: 262	convolution samples Convolution samples "Need" to know what the source is to know how to compare an behave with them. so they have to have a baseline comparison for them to give an accurate example of the sound scape.

November 30th, 2007, 11:02 AM	#5
Chris Barcellos Inner Circle Join Date: Nov 2005 Location: Elk Grove CA Posts: 6,838	Emre: Not sure what you are asking, and I am a novice at the sound side, but used a 1 k tone generated by the audio mixer in a movie I was DP on earlier this year. I since bought a tone generator from BH that plugs into XLR port to set levels. It has several different tones. Don't have any idea if that is what you are after. __________________ Chris J. Barcellos

November 30th, 2007, 11:19 AM	#7
Chris Barcellos Inner Circle Join Date: Nov 2005 Location: Elk Grove CA Posts: 6,838	This is what I got, if it helps anything: http://www.bhphotovideo.com/c/produc...ion_Audio.html __________________ Chris J. Barcellos

November 10th, 2007, 01:53 PM	#3
Emre Safak Trustee Join Date: Feb 2004 Location: Brookline, MA Posts: 1,447	I could not relate what you said to my question.

November 30th, 2007, 08:54 AM	#4
Emre Safak Trustee Join Date: Feb 2004 Location: Brookline, MA Posts: 1,447	I'd like to try one more time! Does anyone actually use a sweep generator? How much does yours cost and is it portable?

November 30th, 2007, 11:14 AM	#6
Emre Safak Trustee Join Date: Feb 2004 Location: Brookline, MA Posts: 1,447	Thanks for responding, Chris. The way it works is that you play a sine wave rising in frequency (a "sweep") and record it. I'm interested in how well it works (since practical environments are unlikely to be quiet for the duration of a sweep). The tone is not of a fixed frequency. The generators I'm finding on Google are much higher-specced (on the frequency scale), and consequently much-higher priced, than I need. The alternative is to get a speaker and play a sweep recording. I am concerned that this method will critically depend on the quality of the speakers (since their frequency response will get convolved into the recording). Also I do not know how I would lug around a receiver to power and feed the monitor. It sounds so impractical, that is why I was wondering what people do in practice. Popping a balloon sounds (forgive the pun) so much more convenient.