Sound and Audio Fundamentals

What is the term for the rate at which vibrations occur in sound?

Frequency (correct)
Wavelength
Amplitude
Displacement

What type of waves do sound travels through the air as?

Transverse waves
Longitudinal waves (correct)
Electromagnetic waves
Mechanical waves

What is the range of frequencies that the human ear can detect?

10 Hz to 10 000 Hz
1 Hz to 1 000 Hz
20 Hz to 20 000 Hz (correct)
100 Hz to 100 000 Hz

What is the term for the compression of air particles when a vibrating surface moves closer to them?

Compressions (C) Signup and view all the answers

What is the minimum particle displacement that the human ear can detect?

0.0000001 millimeters (A) Signup and view all the answers

Why are intercom systems necessary in aircraft?

To reduce the noise in the cockpit area (D) Signup and view all the answers

What is a common characteristic of intercom and telephone systems?

They allow both persons to talk and listen at the same time (A) Signup and view all the answers

What is the purpose of an antenna in a radio transmission system?

To generate an EM field (C) Signup and view all the answers

What type of current is required to produce an expanding and collapsing EM field?

AC current (B) Signup and view all the answers

What determines the required length of an antenna for effective transmission?

The frequency of the signal to be transmitted (D) Signup and view all the answers

What is the range of frequencies for human voice in normal speech?

90 Hz to 10 kHz (C) Signup and view all the answers

What happens to the EM field when an electric current is transmitted along a conductor?

It develops an EM field (D) Signup and view all the answers

What is the wavelength of a carrier frequency of 10 megahertz?

30 meters (C) Signup and view all the answers

What is the primary method of rejecting noise in AM receivers?

There is no means of rejecting noise (C) Signup and view all the answers

What is the main advantage of frequency modulation over amplitude modulation?

It is more resistant to amplitude noise (C) Signup and view all the answers

What is the primary characteristic of the wave that is changed in amplitude modulation?

Amplitude (D) Signup and view all the answers

What is the primary method of modulating a radio wave?

Changing the frequency or amplitude (D) Signup and view all the answers

Why is frequency modulation used instead of amplitude modulation?

It is more resistant to amplitude noise (C) Signup and view all the answers

What is a limitation of satellite communication systems in aircraft?

High cost and space requirements (D) Signup and view all the answers

What is a characteristic of full duplex operation in aircraft communication systems?

Needs a full suite of hardware for both transmitter and receiver (D) Signup and view all the answers

How are satellite calls, mainly over water, connected to the public telephone network?

Through a satellite earth station (D) Signup and view all the answers

What is required to provide connectivity to each passenger seat in an aircraft?

Significant additional wiring and control boxes (D) Signup and view all the answers

What is the purpose of a transceiver in a passenger communication system?

To send information from the phone handset to the ground radio base station (C) Signup and view all the answers

What type of data can be transmitted through a radio link between an aircraft and the ground?

Virtually unlimited types of data (B) Signup and view all the answers

What is the primary factor that affects the range of HF radio transmissions?

Frequency selected and time of day (C) Signup and view all the answers

Why do aircraft HF transmitters typically have higher output power than VHF transmitters?

To achieve long-distance communications (C) Signup and view all the answers

What is the primary reason why jet aircraft rarely have long wire HF antennas?

They are not suitable for high-speed flight (D) Signup and view all the answers

What is the purpose of the weak point in an HF antenna installation?

To prevent damage or loss of control in case of breakage (C) Signup and view all the answers

What is the typical configuration of an HF antenna on a light aircraft?

From a wingtip to the tail and then down to the HF transceiver (B) Signup and view all the answers

What is the primary advantage of HF radios over VHF radios in aircraft communications?

Longer range and global coverage (C) Signup and view all the answers