Chapter 8: Audio

Introduction to Audio in Video

  • Audio is critical in videos, often providing around 80% of the informational value.
  • Good audio typically goes unnoticed whereas bad audio is immediately recognized.
  • Therefore, audio plays a pivotal role alongside video in conveying messages effectively.

Importance of Audio in TV Programs

  • Viewer preference regarding audio and video can vary based on the type of program.
  • Discussion points include:
    • Which aspect viewers prioritize: audio or video?
    • How the program type influences this preference.

Microphones: Function and Variety

  • Microphones convert audio into electrical signals for recording and amplification.
  • There are different types of microphones designed for specific applications.
  • A microphone suited for singing may not be optimal for news broadcasting.

Key Features of Microphones

  • Frequency Response: Refers to the microphone's ability to capture different frequencies.
    • Measured in cycles per second (CPS) or Hertz (Hz).
    • Frequency range: Humans hear from approximately 20 Hz (bass) to 20,000 Hz (treble).
  • Pickup Patterns: The directions from which microphones capture sound.
    • Types include Omnidirectional, Unidirectional (Cardioid), Supercardioid, and Bidirectional.

Characteristics of Frequency and Amplitude

  • Frequency:
    • Higher frequencies equate to higher pitches.
    • Specialized microphones may capture high-frequency sounds like a dog whistle (up to 54,000 Hz).
  • Amplitude:
    • Refers to the strength or volume of sound, measured in decibels (dB).
    • Dynamic range indicates the range of loudness a microphone can effectively handle.

Pickup Patterns Explained

  • Omnidirectional: Captures sound from all directions. Useful for ambient sounds.
  • Unidirectional/Cardioid: Focuses on sound from a specific direction (heart-shaped pickup).
  • Supercardioid: Narrower focus, diminishing side sounds to capture audio from the front.
  • Bidirectional: Captures sound from both front and back, ideal for conversations.

Microphone Construction and Types

  • Microphones work by using a diaphragm that vibrates with sound waves, which generates electrical signals.
  • Dynamic Microphones:
    • Rugged, suitable for live performances. They utilize a diaphragm, coil, and magnet to produce sound.
  • Condenser Microphones:
    • Ensure high-quality sound due to a diaphragm and backplate acting as a capacitor.
    • Require an external power source (battery or phantom power) but offer better frequency response.

Microphone Positioning & Usage

  • Microphones come in various forms:
    • Lavalier (lav), handheld, tabletop, boom mics, shotgun mics, and pressure-zone mics (PMZ).
  • Positioning: Proper positioning is essential to minimize echoes and enhance sound quality.

Audio Sampling Rate and Depth

  • Sampling Rate: The frequency at which analog audio signals are converted to digital (commonly 44.1 kHz or 48 kHz).
  • Bit Depth: Determines audio quality by specifying how much data can represent each sample.
  • Bit Rate: Refers to the number of bits processed per second.

Cables and Connectors

  • Audio cables transport signals and vary between types: copper or fiber optics.
  • Key types of connectors include XLR, USB, phone (3.5 mm), BNC, RCA, and mini-phone connectors.

Audio Consoles

  • Audio consoles manage sound through various functions:
    • Power supply, input, signal processing, mixing, isolating, outputting, and monitoring the audio.

Monitors and Speakers

  • Speakers serve as transducers turning electrical signals back into audible sound;
  • They are essential for monitoring audio in a control room environment.
  • A program monitor plays the main audio output, while an air monitor allows hearing the live broadcast feed.

Tips for Quality Sound Recording

  • Select appropriate microphones for each situation.
  • Properly position the microphones for optimal sound capture.
  • Understand and apply the inverse square law related to sound.
  • Conduct thorough sound checks prior to recording.
  • Develop troubleshooting strategies for common audio issues.

Common Audio Problems in Media

  • Discuss common irritations related to audio when watching TV:
    • Mismatched lip-sync with audio, excessive background noise,
    • Volume inconsistencies where soft-spoken dialogue requires high volume adjustments but creates high spikes in louder speech.