## Microphones and Loudspeakers

Summarize the electrical and magnetic principles underlying the operation of microphones and loudspeakers.

What are the basic types of microphones?

Why are dynamic microphones the most common in use?

Why are condenser microphones the recording studio standard?

What is the significance of "high impedance" and "low impedance" for microphones?

How does a dynamic loudspeaker work?

Why must a loudspeaker be in an enclosure for satisfactory performance?

What is a bass reflex loudspeaker?

*Electricity- water analogy for DC

*Ohm's law examples

*Magnetic forces on charges

*Types of microphones

*Dynamic microphones

*Condenser microphones

*Impedance matching

*Dynamic loudspeaker

*Loudspeaker basics

*Bass reflex loudspeaker

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# Auditorium Acoustics

The basic problems of auditorium acoustics are the inverse square law problem and the "bass loss" problem. Describe these problems.

How is the inverse square law problem addressed?

What can be done about the bass loss problem?

What is the role of reverberation in auditorium acoustics?

What is the definition of "reverberation time" and why is it so important?

What are the perceived characteristics of a good auditorium and how can these characteristics be measured?

*Inverse square law

*Inverse square law plot

*Inverse square law example.

*Intensity vs distance

*The bass loss problem

*The ear's response to bass

*Reverberation

*Reverberation time

*Calculation of reverberation time

*Absorption coefficients

*Characteristics of good auditoriums

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## Sound Reinforcement Systems

Can you reproduce sound as loud as you want in an auditorium provided you have a powerful enough amplifier? What determines the limit of useful sound from a sound amplification system?

What is meant by "feedback"?

What determines the potential acoustic gain of a sound amplification system?

How can the amount of useful gain be increased?

What is the role of directional microphones and directional speakers in increasing the useful amplification?

What is the role of equalization in optimizing a sound amplification system?

Under what conditions is a "notch filter" useful?

*Modeling a sound amplification system

*Feedback

*Potential acoustic gain

*Calculating potential acoustic gain.

*Steps to increase the available amplification

*Directional microphones

*Directional loudspeakers

*Equalization

*Notch filters

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