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Cleaning your microphones (some good advice from Shure Microphones)

Tue, 6 Apr 2010 16:19:07 -0600

You’ve finally invested in a high quality vocal microphone and your voice has never sounded better.
Unfortunately, the keyboard player in your band decides he wants to use your mic during his featured rap. You cringe as he practically eats the microphone.
You can barely watch as he encourages audience members to scream into the mic.
Afterwards he returns your mic, still operational but considerably wetter and unhygienic.
Microphones are subject to an inordinate amount of abuse, especially in live music. Grilles and foam windscreens can become saturated with saliva, clogged with lipstick, and will absorb the smell of cigarette smoke prevalent in most clubs.
Regular cleaning of your microphone will not only improve its performance, but is also good hygiene. This document provides several simple yet effective techniques for cleaning microphones.
Dynamic Microphones  The best way to clean a microphone is to remove the grille. Most vocal microphone grilles simply unscrew, e.g., SM58, BG3.1. If the grille doesn’t slide off easily, gently rock it back and forth while pulling it away from the cartridge. Do not pull sharply or with excessive force, since that could damage the cartridge or separate it from the microphone housing.
Once the grille is removed, it can be thoroughly cleaned without damaging the mic. Since most of the offensive material on the grille comes from the human body, plain water should be a sufficient cleanser. Adding a mild detergent (dishwashing liquid) to the water will act as a mild disinfectant and remove odors absorbed by the foam windscreen.
To remove lipstick and other material stuck in the grille, use a toothbrush with soft bristles. In some models, the foam windscreen can be removed from the grille, but this is usually not necessary since water will not damage the grille. Most Shure microphone grilles have a nickel finish that makes them resistant to rust, and replacing the foam windscreen can also be difficult and time-consuming.
The most important thing to remember is: let the grille dry completely before reattaching it to the microphone! Microphones don’t like water, and although dynamic mics can withstand small amounts of moisture, a soggy foam windscreen will introduce more than is acceptable.
Air drying is the best way to dry the grille, but a hair drier on a low-heat setting can be used. Care must be taken not to get too close to the grille as excessive heat can melt some windscreen material.
Cleaning must be done more carefully for microphones that do not have removable grilles, e.g., SM57, 545.
Using a damp toothbrush, hold the microphone upside down and very gently scrub the grille.
Holding the mic upside down will prevent excess moisture from leaking into the microphone cartridge.
This technique is also useful for cleaning the foam that covers the diaphragm inside an SM58.
Again, keep the mic upside down, and be very gentle.
In live situations with multiple acts, it may be desirable to clean the microphones between acts. Use a diluted solution of mouthwash (Listermint, Scope) with water. Using a toothbrush and holding the microphones upside down, scrub the grille of the microphone.
At the very least, this technique will make the microphones smell more pleasant to the performer. Also make certain the sound system is turned off before the cleaning begins!
Condenser Microphones  Due to the more delicate nature of condenser microphones, never use water or any other liquid for cleaning purposes. Even a small amount of moisture may damage a condenser element.
For microphones with removable grilles like the Beta 87 or BG5.1, the grille and foam windscreen may be washed as described above.
Again, the grille and windscreen must be completely dry before reattaching it to the microphone. To clean a microphone with a permanently attached grille like the SM81 or BG4.1, use a dry, soft bristle toothbrush and gently scrub the grille.
Keep the microphone upside down so that loosened particles fall away from it. Take care not to let stray bristles get caught in the grille. This technique also works well for lavaliers and miniature gooseneck mics.
For condenser microphones that will be subject to harsh conditions, such as vocals and theater applications, it is advisable to use a removable external foam windscreen.
This will protect the microphone from saliva and make-up, and can be removed and cleaned with soap and water after the performance. Remember, never get water near a condenser element!

A special thanks to Shure Microphones for writing this article. They make some of the best!

http://www.CapsicumPro.com

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Psychoacoustics and why people daydream during speeches

Sun, 27 Dec 2009 16:41:11 -0700

So you are at a church service or speaking engagement and watching the guest speaker (or pastor) but the sound seems to come from someplace other than his / her lips? If you closed your eyes and tried to guess where the sound was coming from, you might open your eyes to be staring at the speakers, or even worse, a wall! This kind of issue can be confusing and somewhat tiring for the brain to process, as your eyes are telling you one thing, and your ears another.

As this kind of acoustical phenomenon is tiring to process for the brain, it is also just plain tiring. Often people attending a church service, or speaking engagement, will wonder off into daydreaming or even drowsiness. Not because the person giving the speech is delivering horrible content, but because it is simply too difficult to listen. I recently read a great article on Pro Sound Web, that pointed out this issue of yawning, and daydreaming in church services.

From here I would like to delve into the realm of Psychoacoustics. Psychoacoustics is the study of how sounds are perceived and processed by the human mind. Many venues are plagued with issues relating to psychoacoustics, such as the issue mentioned earlier.

Our brain has many ways of filtering sounds, and processing what is coming into our ears. If we did not have these filters, we would not be able to have a conversation in a restaurant, localize sounds, or be able to decipher the intensity sounds. The less our brain has to process sounds the better we are able to absorb important information, or enjoy our sonic experiences.

One psychoacoustic effect that I would like to focus on is the “Haas Effect” also known as the Precedence Effect, or the Law of the First Wave Front. This effect is responsible
for the ability of listeners with two ears to accurately localize sounds coming from around them.
When two identical sounds originate from two sound sources at different distances, the sound created from the closest location is heard first. The listener perceives that this sound is from that location alone and all later arriving sounds are suppressed, even if the later arriving sound is louder. This could be called “involuntary sensory inhibition”
The Haas Effect occurs when the arrival times of the two sound sources are within 30-40 mili seconds. Any sounds arriving later than 40 mili seconds are perceived as delays or echoes.
So imagine a person on a stage, speaking, is 10 feet behind the main speakers. Obviously you would hear the sound from the speakers first as opposed to hearing the persons actual voice. You would hear the persons actual voice 8.9 mili seconds later than when you heard the main speakers. According to the Haas Effect, your mind would disregard the persons actual voice and perceive that the persons voice is coming from the main speakers.
The Haas Effect often happens because of reflections of sounds as well. Imagine if you’re in the back of a venue and the sound that arrives first is from a reflection off of the back wall. You would perceive that the persons voice is coming from behind you, which could be quite confusing, and would require your brain to work a little more, causing you to daydream as you’re looking at the guest speaker and his voice is coming from behind you.

Many of these issues can be dealt with by proper speaker placement, acoustical treatment of reflections, and time aligning speakers. But the sad case is that many local sound contractors do not understand some of these basic acoustic concepts that are critical to creating an accurate listening environment.

If you have any questions, don’t hesitate to send me an email. Capsicum Pro Audio & Visual would love to help in creating a better listening experience for your audience.

Noah Waldron
Capsicum Pro Audio & Visual
noah@capsicumpro.com

Speech Intelligibility

Tue, 17 Nov 2009 12:20:40 -0700

Speech Intelligibility

Have you ever been to a conference, church service, or any event where a speech is made, and it is hard to understand what is being said? Not because the guest speaker is Charlie Browns school teacher, but because your in a tin building, the speakers are aimed at the ceiling, and the microphone is 5’ from the speakers mouth.

Many sound system designers and day to day engineers do not take into consideration the importance of speech intelligibility. Though, for most of us sound engineers, it is not a life threatening issue. But imagine an event where your potential clients, employees, or congregation did not receive a clear message. Misunderstanding simple words, leading to a false understanding of the message. Or imagine a situation where an air traffic controller is giving instructions to two different pilots and one of them mis-understands one word. Now this situation could be life threatening!

Speech intelligibility issues can come from various situations in the public address system, the interaction of the public address system with the room, placement of microphones, and many more.
In a perfect world, we would only hear the direct sound of the speakers, eliminating the sounds of rooms, and their reflections.
The interaction of a speaker system in a room is very complex to understand, model, or measure. But there are some great tools out there that engineers are using to analyze rooms and their acoustical responses to a public address system. One of these tools is a software called SMAART. "Smaart" stands for Sound Measurement Acoustical Analysis Real Time Tool. Smaart is used to measure PA's in specific venues or recording studios, mainly to initially tune and adjust the PA to operate at it’s maximum potential in a specific venue.
The proper use of SMAART can greatly improve intelligibility, increasing the impact of a speech by the CEO who has something really important to say.

Speech Intelligibility is measured by %ALcons (Percentage Articulation Loss of Consonants). It is computed from measurements of the Direct-to-Reverberant Ratio and the Early Decay Time using a set of correlations defined by SynAudCon, and is specified in percentages.
Consonants play a more significant role in speech intelligibility than vowels. If the consonants are heard clearly, the speech can be understood more easily.
Since %ALcons expresses loss of consonant definition, lower values are associated with greater intelligibility. It is generally assumed that the maximum allowable value for typical paging applications is 10%, assuming that the environment is relatively free of masking noise. For learning environments and voice warning systems, the desired value is 5% or less.
Alcons is the measured percentage of Articulation Loss of Consonants by a listener. % Alcons of 0 indicates perfect clarity and intelligibility with no loss of consonant understanding, while 10% and beyond is heading toward bad intelligibility, and 15% typically is the maximum loss acceptable.

Capsicum Pro Audio & Visual uses SMAART to acoustically correct our sound systems to match the venues and address the issues of reverberation, time alignment, and phase problems that occur in most rooms and venues.
Line Arrays have allowed us to drastically reduce the amount of acoustical energy directed at reverberant surfaces, and focus the energy at the listeners.Greatly enhancing the quality of our services by allowing us to achieve lower %ALcons.
Feel Free to check out our Blog on Line Array technology.
http://www.capsicumpro.com/Site/Blog/Entries/2009/10/14_Line_Array_Speaker_technologies.html

Noah Waldron
noah@capsicumpro.com