I plan to examine the effects of mixed sounds on human mood. I have three types of sounds: nature sound, traffic noise, and mechanical noise. I want to mixed them and produce three types of sound: nature sound dominate (but mixed with traffic noise and mechanical noise at a lower level), traffic noise dominate, and mechanical noise dominate.
I have two proposed ways to produce these three types of sound, let me use the nature sound dominate as an example:
1. Nature sound (keep the original sound volume measured at a point near the sound source) + traffic noise (only 10% of original sound volume: say 80db*10%))+ mechanical noise (only 10% of original sound volume, say 85 db*10%)
2. Nature sound (keep the original sound volume measured at a point near the sound source)+ traffic noise (original sound - decreased db because of distance)+ mechanical noise (original sound - decreased db because of distance). The decreased db can be calculated by the fomula in the link: http://www.sengpielaudio.com/calculator-squarelaw.htm
which one is better and why? or neither is good and you have a good suggestion? Could you recommend any literature as a reference? Many thanks!
I think the choice depends on your purpose. Have you thought of arranging those sources in an binaural audio environment ?
Dear Max,
Thanks for your help. The purpose is to see how urban sound environment influence mood. We normally don't have a chance to hear a pure type of sound. It is always mixed by different sounds. We use a Sony Home Theatre system (surrounding sound environment) to play the sound.
In acoustics it is usual to express the relative strength of the signals in decibels (dB). Relevant numbers in your case are now:
Example, equivalent sound levels: traffic noise 60 dB(A), mechanical noise 55 dB(A), natural sound 50 dB(A); this mix will result in 61.5 dB(A) overall. The relative sound levels are -1.5 resp. - 6.5 ; -10.5 dB(A).
Regarding traffic noise: the distance to a road not only influences the sound level (line source), but also the time history; at short distances the fluctuations will be much larger than at great distances.
Interesting !
It really depends on what you´re after but I would record the sources in the closest possible way (same distance to source, same equipment...etc) so I could then create various mixes with all the material (post-production).
You might also want to consider introducing some of those layers at subliminal levels. For a detailed account of clinical research outcomes on subliminal sound administration procedures see the work of Paul Swingle.
Best of luck and please, keep us posted :)
http://www.soundhealthproducts.com/products/subliminal-treatment-procedures-a-clinicians-guide
One last hint. For the second method I would at least implement a low pass filter to approximate the air absorption (at 100 meters, high frequencies arround 8 kHz, a temperature of 20°C and relative humidity of 60% the sound will have an additional absorption of about 9 dB) . A better way would be the calculation of air absorptiont by the formula you can find in ISO9613-1 ... or use proper values you can find in part 2 of the standard (ISO9613-2).
Best regards,
André
I would recommend the use of Avisoft Soft ware. Open the nature sound using Avisoft SASLab Pro version 5.2. Also open the traffic noise using Avisoft software separately and copy to clipboard. Using the mix option in the edit menu combine it with the nature sound. Repeat the process of mixing with the mechanical noise.
Thanks, Dear Mario.
It is impossible to duplicate the sound condition of real urban environments in a lab setting. Therefore, we can only examine influence from major components (traffic nosie, nature sound, and mechanical noise). The way we mixed the sounds is based on an assumption: we only consider the distance between an audience and sound source and no other complicated factors were assumed identical, such as height and distance of surrounding buildings). Any further thoughts?
The perception of road traffic noise depends not only on the equivalent sound level Leq, but on the variation (e.g. L10 - L90) as well. Doubling the traffic intensity while doubling the distance as well would keep Leq (almost) equal, but the variation will decrease! This example shows that the time history should not be ignored.
Hi Bin, you might want to look at the research leaders in the field of applied soundscape.
You can look at this book for more details: https://www.crcpress.com/Soundscape-and-the-Built-Environment/Kang-Schulte-Fortkamp/p/book/9781482226317
Regarding your application, you might want to look into the work of Dr. Pyoung Jik Lee: https://scholar.google.com/citations?user=TYZB3ZUAAAAJ&hl=en
We use signal-to-mask ratio in digital signal processing as a measure of how "loud" the noise is compared to the masker. I believe Dr. Lee's work has a range of -3dB to +3dB. for signal-to-mask ratio. I can't be sure, let me know if you find any discrepancies. Hope this helps.
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There are a lot of answers here so I may be repeating a response, but what are you doing to consider directivity? gain and color of noise shouldn't be your only consideration. I recall reading a psychoacoustic paper on context a decade ago or so that related the importance of the frequency content that your ear can perceive spatially with how it affects response time.
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