Acoustics

Introduction to Acoustics

  • Acoustics is the study of sound, how it’s produced, controlled, transmitted and received.
  • Sound is a mechanical wave caused by the vibration of particles in a medium, typically air.
  • Frequency refers to the number and speed of vibrations; it’s measured in Hertz (Hz) and affects the pitch of the sound.
  • Amplitude refers to the extent of a vibration or oscillation, this affects the volume or loudness of the sound.

Properties of Sound

  • The speed of sound correlates with temperature, humidity, and pressure. Normally in air, it’s approximately 343 m/s.
  • Sound propagation involves Diffraction, Reflection, Absorption, and Refraction.
  • Diffraction is the bending of waves around obstacles or through openings.
  • Reflection is the process by which sound waves bounce back after hitting a surface.
  • Absorption is the process of sound waves being soaked up and converted into other forms of energy.
  • Refraction is the change in direction of a wave due to a change in speed.

Room Acoustics

  • Important issue in studio design and venue selection for live performances.
  • Reverb and Echo are two key concepts in room acoustics.
  • Reverb is the persistence of sound after it’s produced. It’s created by many reflections of the same sound within a room.
  • Echo is the distinct later arrival of sound reflections more than 50-100ms after the direct sound.

Sounds and Humans

  • The range of audibility for a healthy young individual is typically 20 Hz to 20 kHz.
  • Perceived loudness, pitch, and timbre are three characteristics of a sound determine how we perceive it.
  • Perceived loudness depends on the amplitude and frequency of the sound wave.
  • Pitch is perceived as the fundamental frequency of the sound wave.
  • Timbre is the characteristic that allows us to distinguish between different sounds as varied when they have same pitches and loudnesses.

Understanding Audio Devices

  • Microphones convert sound into an electrical signal.
  • Speakers convert the electrical signal back into sound.
  • The frequency response of an audio device refers to the range of frequencies and associated responses the device can handle.
  • Decibels (dB) is a logarithmic scale used to compare the powers of two quantities, used to measure sound intensity.

Health and Safety

  • Prolonged exposure to high decibel levels could result in hearing loss.
  • Hearing protectors or ear muffs can be used in high noise environments.
  • In general, the safe exposure limit is 85 dB for a maximum of eight hours per day.

These points cover the basic concepts and principles of sound and acoustics. More in-depth study and understanding of these topics will help apply them practically in the field of music technology.