Every online teacher is looking for a good microphone for their online classes. Though chalk and talk business is slowly disappearing, the teachers essentially need a digital pen and board for communicating with the students quickly and efficiently, especially the Maths and Science teachers with lot of mathematical and scientific symbols and equations. Most of the teachers prefer to move here and there while they are talking to their students. Though some teachers prefer collar mic and many teachers look for a stable mic which can record their voices clearly. This article on how to select a good microphone will be useful to them.
Pick up pattern and transducer types are the two essential parameters in selecting a suitable mic.
Types of microphones based on pickup patterns
There are three types of pickup patterns viz., Omnidirectional, Cardioid and Hypercardioid
Omni directional
- Omni means all. It indicates that this type of mic captures sound from all directions.
- They are equally sensitive from all sides and pick up sound from every direction.
- This type of microphone is good for ambient sound and group vocals
- However, it is not suitable for noisy environment!
Cardioid
- Cardioid microphones have the heart shaped pattern.
- They are unidirectional, i.e., they are sensitive in a specific direction.
- Cardioid means heart shaped.
- They reject sound coming from behind the microphone
- They pick up the sound mostly from the front.
- They are ideal for handheld applications.
Hypercardioid
- Hypercardiod microphones are directional
- They eliminates sound most from sides and rear.
- They are useful when there is a lot of ambient noise
- They pick up sound from a subject at a distance.
Types of microphones based on transducer types
Based on the transducer types, there are two types of microphones viz., dynamic and condenser types.
Dynamic microphone transducer
- A coil of wire is mounted on a diaphragm in a dynamic microphone.
- This coil is kept in a magnetic field.
- The sound causes vibrations in the diaphragm.
- This produces lot of fluctuations in the magnetic field
- Electric current is created because of mechanical fluctuations in the magnetic field according FBI (Force (F), Magnetic field (B) and Current (I)) rule, called Fleming’s left hand rule.
- Fleming’s left hand rule states that stretch the forefinger, middle finger and thumb of left hand in such a way they are mutually perpendicular to each other as shown in the diagram. If magnetic field acts along direction of forefinger, mechanical force of conductor acts along thumb, current is produced along the direction of middle finger.
- The A.C. signals thus produced are sent to mixer or amplifier.
- Dynamic microphones are rugged.
- They can handle high sound pressure levels.
- They are ideal for drums and some aggressive vocals.
Condenser microphone Transducer
- Condenser microphone require constant electric charge.
- It is provided by a battery.
- Condenser diaphragm has less mass than the dynamic microphones.
- They require less energy to move.
- They are more sensitive than dynamic microphones.
- They are very responsive to high frequencies produced by guitars or cybals.
There are other parameters such that impedance and frequency response.
Impedance
- Low impedance microphone: 200 – 1000 ohms
- High impedance microphones: 10,000 – 50,000 ohms
- If a microphone is connected to an input with lower impedance, the signal strength is reduced.
Frequency response
- Flat frequency response are equally sensitive to all frequencies.
- The exhibit accurate representation of original sound.
Tailored frequency response
- May be more useful in some cases when selective frequencies are preferred.
Features of Blue Yeti Microphone
Now, let us discuss why we preferred Blue Yeti Microphone. It has all essential four modes of patterns, viz., cardioid, stereo, bidirectional and omnidirectional. It has a stable stand with USB plug and play system. It is equipped with a headphone jack to listen to the real time recording. Hence it is ideal for a single teacher or teacher with students, musicians and vocalists too. Logitech C930e webcamera with a Blue Yeti is an ideal combination to make an effective presentation in a meeting room as well as in a classroom.
References
- Sound guys
- Dismakers
- ESR Electronic components
- Text book of Physics, NCERT