This is why it is better to calculate relative non-absolute values of distance. Using this ideology, microphones can be compared with the human ear. Then we can write:. Where R0 — a distance of hearing a sound with the human ear, R- distance with a directional microphone, G0 — ear directional coefficient. Practically speaking, if we compare the human ear and directional microphone in the city noisy area , values would be like human ear can hear human speech at a distance of about 2- 4m and directional microphone can from about 6 — 12m.
Outside the city, where the noise level is low, the ear can hear at 10m while the directional microphone is more than 30m. There are more advanced methods like digital multichannel filtering and high sensitivity sensors where the threshold may reach dB.
Sensitivity can also be increased by increasing the size of the antenna. As we mentioned initially, calculation shows that reaching or m distances with directional microphones is quite difficult.
Typically, directional microphones in the market can effectively register human speech 76dB at distances close to 50m. Today spy technologies are accessible for everyone. Mobile apps such as TheTruthSpy can make smartphones fully-featured remote trackers, microphones, and loggers. Techno Tip : It is easy to stay productive by moving your app development and testing environment to the Cloud with hosted xendesktop at the lowest price with excellent support by Apps4Rent.
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Thank you, What do you mean packed with people? Could you give me a hint that I could improve the situation. Thank you. Hi, I was curious about your calculation of G for the flat microphones. What does the variable p represent? Is S total or individual aperture area?
Filtering as the hearing aid mfgs. Filter them out and I filter out the person that I am trying to hear. I would like to add a very directional mic to my H-A input in place of the normal mics.
After reading your report, it seems as though a flat directed mic would work best in this case. What do you think? Has anyone else asked this question? Scientifics has up to 2 foot dishes. I used the hardware dish and handle with a Primo Microphone EM A Radio Shack electret mike worked well and I was satisfied until I tried the Primo low noise mikes and they are only two wire mikes, too.
So a cardioid microphone appears to enhance sound waves from the front, by being far less sensitive to sound waves from the left, right, and rear. Myth: A microphone has a reach specification that can be measured in feet or meters. Let's use an example. For a nature film, you want to record the call of a wolf in the wilderness of Canada.
The recording conditions are superb. There is no wind; the closest town is miles away; your equipment is a state-of-the-art digital recorder with a quiet mic preamplifier. Your microphone is an omnidirectional dynamic. The wolf howls for two minutes and you obtain a fantastic recording. You immediately activate your digital recorder and hang the same omnidirectional microphone outside your window to record the wolf, but much to your surprise all you hear is traffic and wind noise when you play back the recording.
The wolf cannot be heard even though you saw it howling through your binoculars. Did the reach of the microphone somehow change? No, only the ambient noise conditions changed. Myth: A shotgun microphone is like a zoom lens on a camera.
The basic directional types include cardioid, subcardioid, hypercardioid and bidirectional. To get equal volume, he would have to move to half the distance from the mic. A word of caution: these polar patterns are run in an anechoic chamber, which simulates an ideal acoustic environment — one with no walls, ceiling or floor.
In the real world, walls and other surfaces will reflect sound quite readily, so that off-axis sound can bounce off a nearby surface and right into the front of the microphone.
So cardioid microphones can help reduce unwanted sound, but rarely can they eliminate it entirely. The directional microphone illustrated in Fig. The maximum angle within which the microphone may be expected to offer uniform sensitivity is called its acceptance angle. As can be seen in Fig. This will often vary with frequency. One of the characteristics of a high-quality microphone is a polar pattern which changes very little when plotted at different frequencies.
As Fig. If the unwanted noise is arriving from one direction only, however, and the microphone can be positioned to place the null of the pattern toward the noise, the directional microphones will offer much greater working distances.
If you are in a very noisy environment, and can point the microphone away from the noise, a comparison will show a better ratio of wanted to unwanted sound with the cardioid than with the omni. This is known as proximity effect see page 12 , a characteristic that is not shared with the omni microphone used for comparison. Selecting a Polar Pattern Whether you should select a directional or omnidirectional microphone can depend on the application recording vs.
Directional microphones can suppress unwanted noise, reduce the effects of reverberation and increase gain-before-feedback. And in a public address application, loudspeaker positioning often dictates microphone location and overrides the Distance Factor in determining the maximum distance from talker to microphone. Find An Answer Browse our vast Answer database for answers to many common technical questions.
Search the Knowledge Base What is the distance factor of a microphone? Fields Title. URL Name. FAQ Question. I've heard the term "distance factor" used with microphones. What does it mean?
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